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Sciences 

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23  WIST  MAIN  STRUT 

WMSTER,N.Y.  14SS0 

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CIHM/ICMH 

Microfiche 

Series. 


CIHIVI/ICMH 
Collection  de 
microfiches. 


Canadian  Institute  for  Historical  IVIicroreproductions  /  Institut  Canadian  de  microreproductions  historiques 


Technical  and  Bibliographic  Notes/Notes  techniques  et  bibliographiques 


The  Institute  has  attempted  to  obtain  the  best 
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the  usual  method  of  filming,  are  checicdd  below. 


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I      I    Coloured  maps/ 


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Encre  de  couleur  (i.e.  autre  que  bieue  ou  noire) 


I     I   Coloured  plates  and/or  illustrations/ 


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Coloured  pages/ 
Pages  de  couleur 

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Pages  endommagtes 

Pages  restored  and/or  laminated/ 
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The  copy  filmed  here  hes  been  reproduced  thenks 
to  the  generosity  of: 

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The  last  recorded  frame  on  each  microfiche 
shall  contain  the  symbol  ^»>  (meaning  "CON- 
TINUED"), or  the  symbol  y  (meaning  "END"), 
whichever  applies. 


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dernidre  image  de  cheque  microfiche,  selon  le 
cas:  le  symbols  — ►  signifie  "A  SUiVRE",  le 
symbols  V  signifie  "FIN". 


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different  reduction  ratios.  Those  too  large  to  be 
entirely  included  in  one  exposure  ere  filmed 
beginning  in  the  upper  left  hand  cornea.  Heft  to 
right  and  top  to  bottom,  as  many  frames  as 
required.  The  following  diegrems  illustrate  the 
method: 


Les  cartes,  planches,  tableaux,  etc..  peuvent  dtre 
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de  I'angle  sup6rieur  gauche,  de  gauche  d  droite. 
et  de  haut  en  bas,  en  prenant  le  nombre 
d'images  n6cessaire.  Les  diagrammes  suivants 
illustrent  ia  mdthode. 


1  2  3 


1 

2 

3 

4 

5 

6 

BY  THE  SAME  AUTHOR. 


Chemical  and  Geological  Essays. 

Second  llevised  Edition,  witli  a  New  Preface; 
pp.  xlvi.  and  489;  8vo. 


«» 


XN"   PRE1F-A.RA.TION" : 

MINERALOGY 

ACCORDIKO  TO 

A  NATURAL  SYSTEM. 


Thb  outlines  of  this  system  —  the  result  of  more  than  thirty  years 
of  study — are  given  in  the  author's  Mineral  Physiology  and 
Physiography,  pp.  279-401,  687,  688,  where  a  tabular  view  of  Classes 
and  Orders  appears  on  page  382.  The  principal  points  in  the  new 
treatise  are:  (1)  Arrangement  of  all  native  and  artificial  species  of 
the  mineral  kingdom  in  classes  and  orders,  upon  a  Chemical  basis; 
(2)  Their  complex  chemical  structure  and  high  combining  numbers, 
or  so-called  molecular  weights;  (3)  Application  to  them  of  the 
principles  of  polyraerlsm  and  of  homologous  or  progressive  series; 
(4)  Direct  relations  of  the  constitution  of  solids,  not  only  to  their 
specific  gravity,  but  to  their  hardness  and  their  greater  or  less 
chemical  indiflference,  which  latter  are  shown  to  be  connected  with 
the  variations  in  the  volume  of  the  chemical  unit,  or  so-called  atomic 
volume ;  (5)  Recognition  of  the  wide  distinction  between  crystalloid 
and  colloid  or  amorphous  species ;  (6)  Division,  on  the  above  grounds, 
of  the  orders  and  sub-orders  into  tribes,  which  generally  correspond 
with  the  orders  of  the  Natural-History  system;  (7)  Sub-division 
of  tribes  into  genera  and  species,  and  designation  of  these  by  a 
binomial  Latin  nomenclature ;  (8)  Systematic  descriptions  of  native, 
and  of  some  related  artificial  species ;  (9)  Genetic  history  of  native 
species,  and  their  artificial  production;  (10)  Their  relations  to  the 
great  groups  of  rocks  in  the  earth's  crust. 


MINERAL 


Physiology  and  Physiography. 


A   SECOND  SEBIES  OF 


CHEMICAL  AND  GEOLOGICAL  ESSAYS 


WITH 


A  GENERAL  INTRODUCTION. 


'BY 
THOMAS  STERUY  HUNT,  M.A.,  LL.D.  (Cantah.) 

FtUow  of  the  Royal  Society  of  London ;  Member  of  the  National  Academy  of  Sclencea  of  the  United 

States,  the  Imperial  Leopoldo-Carolinian  Academy,  the  American  Philosophical  Society, 

the  American  Academy  of  Sc!onces,  the  Royal  Society  of  Canada,  the 

Geological  Societies  of  France,  Belgium,  and   Ireland; 

OfBcer  of  the  Orders  of  the  Legion  of  Honor, 

88.  Mauritius  and  Lazarus, 

etc.,  etc.,  etc.  , 


BOSTON: 
SAMUEL    E.   CASSINO. 

1886. 


Copyright,  1886, 
By  Samuel  E.  Cassino. 


Electrottpkd  by 
G.  J.  Peters  &  Son,  Boston. 


TO 


€ffz  Mmot^ 


or 


BENJAMIN    SILLIMAN, 

WHO  DIED  1,35. 


\-2^ 


MINERAL 


PHYSIOLOGY  AND  PHYSIOGRAPHY. 


A  SECOND  SERIES  OP  CHEMICAL  AND 
GEOLOGICAL  ESSAYS. 


PREFACE. 


The  second  title  assigned  to  this  volume,  —  namely, 
Chemical  and  Geological  Essays,  —  fails  to  indicate 
its  character  and  scope,  by  reason  of  the  indefiniteness  of 
the  word  Gcv  'ogy,  which  is  now  commonly  used  to  desig- 
nate both  the  Natural  Philosophy  and  the  Natural  History 
of  our  earth,  except  so  far  as  modern  geography  and 
meteorology,  and  the  existing  flora  and  fauna,  are  con- 
cerned ;  descriptive  mineralogy  and  lithology  being  insep- 
arable from  the  study  of  the  earth's  crust.  In  this  popular 
sense,  geology  is  made  to  include  the  whole  history  of 
organic  life  in  past  ages,  —  a  field  which  rightfully  belongs 
to  botany  and  zoology.  The  fossil  remains  of  extinct 
organic  forms,  valuable  as  they  may  be  in  the  diagnosis  of 
stratified  sedimentary  strata,  have,  however,  no  geognostic 
significance  save  in  their  chemical  and  lithological  rela- 
tions ;  and  paleontology  should,  therefore,  be  distinguished 
alike  from  geogeny  and  geognosy. 

The  proper  application  of  these  two  terras  is  defined 
farther  on,  in  an  essay  on  The  Order  of  the  Natural  Sci- 
ences. Therein  will  be  seen  the  subordination  of  geogeny 
to  dynamics  and  chemistry,  and  of  geognosy  to  descriptive 
and  systematic  mineralogy,  which  are  included  under  the 
respective  heads  of  Mineral  Physiology  and  Mineral  Phy- 
siography, suggesting,  as  the  more  definite  title  of  the 
volume.  Mineral  Physiology  and  Physiography. 
The  essays  of  which  it  is  made  up  have  been  written  in 
accordance   with   a  predetermined   plan,  which  is  now 


TRErACE. 


accomplished.  The  first  and  second  are  intended  to  serve 
as  a  General  Introduction,  and  to  show  the  relations  of 
the  natural  sciences  to  each  other  and  to  that  complex 
study  which  we  call  geology.  In  writing  the  six  succeed- 
ing essays  it  w.is  the  author's  design  to  bring  together,  in 
a  concise  form,  the  facts  and  the  reasonings  from  which 
are  deduced  what  he  regards  as  the  Principia  of  geugeny, 
geognosy,  and  mineralogy. 

The  chemistry  of  the  atmosphere,  and  the  relations  of 
the  earth's  aerial  envelope  alike  to  outer  space  and  to  the 
gases  condensed  and  the  waters  precipitated  on  the  sur- 
face of  the  globe,  as  set  forth  in  the  third  and  fourth 
essays,  constitute  a  necessary  preliminary  to  the  study  of 
rock-masses.  These,  in  Essays  V.,  VI.,  VII.,  are  consid- 
ered from  three  different  points  of  view;  the  genesis 
and  the  geognostic  relations  of  the  various  crystalline 
rockss,  and  finally  the  decay  of  these,  which  has  deter- 
mined their  present  surface-outlines,  and  has  given  rise  to 
the  materials  of  the  uncrystalline  sedimentary  strata.  In 
the  fifth  essay  an  attempt  has  been  made  to  show  the 
defects  of  each  of  the  many  contradictory  hypotheses 
hitherto  proposed  to  explain  the  origin  of  the  crystalline 
rocks,  and  to  set  forth  a  new  one,  according  to  which 
they  have  been  derived  —  for  the  most  part  indirectly  and 
by  aqueous  solution  —  from  a  single  primary  plutonic 
mass,  which  itself,  however,  modified  both  by  the  action 
of  water,  and  by  partial  separations  through  crystalliza- 
tion and  eliquation,  has  been  the  direct  source  of  many 
exotic  rocks.  All  of  these  points  are  more  fully  discussed 
in  Essay  VI. 

The  new  hypothesis,  as  set  forth  in  Essays  V.  and  VI., 
is  the  result  of  nearly  thirty  years  of  studies  having  for 
their  object  to  reconstruct  the  theory  of  the  earth  on  the 
basis  of  a  solid  nucleus,  to  reconcile  the  existence  of  a 
solid  interior  with  the  flexibility  of  the  crust,  to  find  an 

'  it     '  ' 


PREFACE. 


Vll 


adequate  explanation  of  the  universally  inclined  and  pli- 
cated condition  of  the  older  crystalline  strata,  and  at  the 
same  time  to  discover  the  laws  which  have  governed  the 
formation  and  the  changing  chemical  composition  of 
the  crystalline  rocks  through  successive  geologic  ages. 

The  mineral  species  which  make  up  the  earth's  crust 
next  demand  attention.  A  system  of  classification  which 
should  consider  their  physical  ciuiracters,  in  connection 
with  the  chemical  composition  and  tiie  mode  of  formation 
of  mineral  sjjecies,  has  hitherto  been  wanting.  The 
possibility  of  such  a  system,  and  the  principles  upon 
which  it  might  be  founded,  were  pointed  out  by  the  author 
in  a  series  of  papers  more  than  thirty  years  since.  He 
has  now,  in  the  eighth  essay  of  the  present  volume,  at- 
tempted to  apply  these  principles  to  the  study  of  the 
natural  silicates,  which  are  the  most  important  elements 
of  the  crystalline  rocks,  and  to  give  for  these  species 
what  he  believes  to  be  a  natural  classification,  —  followed 
by  an  outline  of  the  system  as  applied  to  all  other  native 
mineral  species. 

The  origin  of  mineral  species,  their  succession,  their 
associations,  and  the  modes  of  their  occurrence  alike  in 
massive  and  in  stratified  rocks,  in  veinstones,  and  in  the 
chemist's  laboratory,  —  in  other  words,  the  physiological 
history  of  mineral  species  and  their  various  aggregates, 
considered  both  dynamically  and  chemically,  as  set  forth 
in  Essays  V.  to  VIII.,  must  form  the  basis  of  a  rational 
mineralogy  and  lithology.  In  this  connection  are  dis- 
cussed some  fundamental  principles  long  maintained  by 
the  author,  and  believed  by  him  to  form  the  basis  of  "  a 
correct  mineralogical  system,"  and,  moreover,  to  "  enlarge 
and  simplify  the  plan  of  chemical  science." 

That,  contrary  to  the  teachings  of  the  Huttonian  or 
metamorphic  school  in  geology,  there  is  an  order  in  the 
succession  of  the  rocks  from  the  ante-gneissic  granite,  and 


VIU 


PREFACE. 


that  mineralogical  constitution  and  litliological  characters, 
when  rightly  interpreted,  are  a  sure  guide  to  the  relative 
ages  of  the  various  groups  of  stratified  crystalline  rocks, 
was  a  conclusion  early  forced  upon  the  author  by  his 
studies  of  these  alike  in  North  America  and  in  Europe ; 
and  has  led  him  to  propose  stratigraphical  divisions  and  a 
nonienclature  which  are  to-day  more  or  less  generally 
recognized  on  both  sides  of  the  Atlantic.  These  studies, 
from  1847  to  1878,  were  presented  in  a  volume  on  Azoic 
Rocks,*  published  in  the  latter  year,  and,  with  additions 
up  to  1885,  are  now  briefly  resumed  in  the  ninth  essay. 

intimately  connected  with  this  subject,  and  at  the  same 
time  bearing  directly  upon  the  different  hypotheses  touch- 
ing the  genesis  of  crystalline  rocks,  is  the  history  of  the 
serpentines,  which  have  been  alternately  regarded  as 
igneous  and  as  aqueous,  as  exotic  and  as  indigenous 
masses,  and  in  either  case  were  supposed  to  hp.ve  been  the 
subject  of  various  metasomatic  changes.  In  the  tenth 
essay,  the  origin  and  the  geogiiostic  relations  of  these 
rocks,  as  found  alike  among  eozoic  and  paleozoic  strata, 
are  considered,  and  in  this  connection  the  history  of  many 
crystalline  eozoic  groups  on  both  continents,  but  espe- 
cially in  central  and  southern  Europe,  has  been  reviewed, 
—  thus  continuing  the  subject  begun  in  the  preceding 
essay. 

In  concluding,  in  the  eleventh  and  final  essay,  the 
review  of  the  geognostical  uistory  of  the  crystalline  rocks, 
continued  from  Essays  IX.  and  X.,  the  question  of  the 
BO-  ailed  Taconic  rocks  has  been  discussed  at  some  length, 
anii  for  two  reasons.  First,  because  the  Lower  Taconic 
series,  which  has  been  designated  Taconian,  appears,  as  is 

•  Azoic  Rocks,  etc.,  by  T.  Sterry  Hunt :  Part  I.  Historical  Introduc- 
tion, 1878,  8vo,  pp.  xxi.  and  253,  being  Report  E  of  the  Second  Geologi- 
cal Survey  of  Pennsylvania,  Harrisburg,  Penn. ;  Part  II.,  which  would 
have  been  a  special  study  of  these  rocks  in  Pennsylvania,  has  never  ap- 
peared, but  many  details  thereon  are  given  in  Essay  XI.  of  this  volume. 


PREFACE. 


here  shown,  to  be  widely  spread  over  both  continents,  and 
to  mark  the  latest  known  period  in  the  genesis  of  crystal- 
line stratified  rocks ;  and,  secondly,  because  this  Taconian 
series  has  been  by  some  geologists  supposed  to  represent 
one  of  the  stages  in  an  imagined  process  of  regional 
metamorphism  by  which  one  and  the  same  group  of  un- 
crystalline  paleozoic  sediments  has  been  made  to  assume 
Buccessi\'ely,  in  contiguous  areas,  the  characters  of  the 
various  crystalline  series  from  the  Taconian  down  to  the 
Laurentian,  both  included.  To  expose  the  fallacies  of  this 
ancient  error,  and  to  clear  up  many  of  the  obscurities 
which  it  has  thrown  alike  over  the  history  of  theso  groups 
of  crystalline  rocks  and  the  succeeding  Cambrian  and 
Ordovician  strata,  it  was  found  necessary  to  examine  in 
some  detail  the  record  of  stratigraphical  research  in  the 
pre-Silurian  areas  of  North  America,  and  in  so  doing  to 
render  justice  to  the  work  of  Amos  Eaton,  who,  more  than 
fifty  years  since,  laid  on  a  sound  basis  the  foundations  of 
American  geology. 

In  a  volume  of  selected  papers,  published  by  the  author 
in  1874,  with  the  title  of  Chemical  and  Geological 
Essays,  in  which  were  discussed  the  geognostic  relations 
of  the  Appalachians,  of  the  Alps,  and  of  the  Cambrian  and 
Silurian  rocks  of  North  America  and  Europe  as  known 
up  to  that  time,  the  outlines  of  the  present  stratigraphi- 
cal scheme  for  the  eozoic  and  the  lower  paleozoic  rocks 
were  already,  for  the  greater  part,  defined ;  but  the  true 
relations  of  the  Taconian  were  not  then  understood.  In 
a  Preface  to  a  second  edition  of  that  volume,  in  1878,* 
the  Taconic  question  was,  however,  reconsidered  (pp. 
xix-xxvi),  and  the  a  ithor's  present  conclusions  are  there 
briefly  set  forth. 

The  volume  just  named  contains,  moreover,  essays  on 

*  Chemical  and  Geological  Essays,  by  Thomas  Sterry  Hunt,  2d  ed., 
1&7S  8  vo.,  pp.  xlvi,  aud 489.    S.  £.  Cassiuo,  Salem  [now  of  Boston],  Mass. 


PREFACE. 


the  origin  of  limestones,  dolomites,  and  gypsums ;  on  the 
chemistry  of  natural  waters,  and  on  petroleum,  asphalt, 
and  coal ;  on  granitic  and  other  veinstones ;  and  on  the 
theory  of  ore-deposits.  Elsewhere  therein,  and  especially 
in  the  first  eighty  pages,  will  be  found  the  beginnings  of 
the  theoretical  views  maintained  in  the  present  volume,  in- 
cluding disquisitions  on  the  nature  and  the  seat  of  volcanic 
action,  and  on  various  other  points  of  dynamical  geology, 
considered  in  connection  with  the  solidity  of  the  earth's 
interior.  Farther  on,  in  pages  426-448  of  that  volume^ 
are  defined  the  principles  of  the  mineralogical  system 
which  is  here  developed  in  the  essay  on  A  Natural  Sys- 
tem in  Mineralogy. 

The  essays  in  the  present  volume,  with  the  exception 
of  the  sixth,  have  already  appeared  in  the  Transactions  of 
the  Royal  Society  of  Canada,  in  the  Proceedings  of  the 
Philosophical  Society  of  Cambridge,  England,  the  Ameri- 
can Journal  of  Science,  or  the  London,  Edinburgh,  and 
Dublin  Philosophical  Magazine,  A  brief  notice  here  pre- 
fixed to  each  essay  gives  "he  diite  and  the  conditions  of 
its  first  appearance.  Change;^  have  occasionally  been 
made  in  revision,  but  wherever  there  is  an  addition  of 
significance  it  is  placed  within  brackets.  The  same  ha-s 
been  done  in  the  case  of  additional  notes. 

The  plan  of  the  present  volume  was  discussed  not  many 
ruonths  since  with  t'  e  author's  honored  master  and  his 
friend  of  forty  years,  Benjamin  Silliman,  tu  whom  the 
volume  would  have  been  inscribed.  It  is  now  dedicated 
to  his  memory. 

Boston,  Massachusetts, 
August,  1886. 


CONTENTS. 


I.— NATURE  IN  THOUGHT  AND  LANGUAGE  (pages  1-26). 

1.  H18TORICA.L.  —  Meaning  of  physics  and  physiology  from  Aristotle  to 

Newton,  1.  Hippocrates;  the  school  of  Alexandria,  8.  Physician 
and  mediciner,  10. 

2.  Philosophical.  —  Physics,  physiology,  and  physician   in   modern 

science,  11.  Dynamics,  chemics,  and  biotics,  13.  Belations  of 
colloids,  18.  Life  in  matter,  20.  Physiophilosophy  of  Oken,  23. 
Mineral  physiology,  25. 

IL— THE  ORDER  OF  THE  NATI'RAL  SCIENCES  (pages  27-29;. 

Natural  History  and  Natural  Philosophy,  or  general  physiogra- 
phy and  physiology,  27.  Dynamic,  chemic,  and  biotic  relations,  28. 
Tabular  view  of  the  natural  sciences,  29. 


III.  — CHEMICAL    AND    GEOLOGICAL    RELATIONS   OF   THE 
ATMOSPHERE   (pages  30-50). 

Action  of  the  atmosphere  on  the  earth's  crust,  30.  Fixation  of 
carbonic  dioxyd,  34.  Sources  of  this  gas,  38.  Hypothesis  of  an 
interstellary  gaseous  medium,  40.  Dynamic  relations  of  such  a 
medium,  41.  Its  geological  relations,  43.  Its  astronomical  rela- 
tions, 46.    Solar  physics  and  cosmic  evolution,  48. 


IV.  — CELESTIAL  CHEMISTRY  FROM  THE  TIME  OF  NEWTON 

(pages  51-67). 

Newton's  Hypothesis  touching  Light  and  Color,  51.  Stellar 
chemistry,  and  dissociation,  52.  Stolchiogeny,  55.  Newton  on  inter- 
stellary ether,  57.  His  Principia  and  Optics  examined,  58.  Later 
writers  on  interstellar  space,  62.  Terrestrial  relations  of  an  inter- 
stellar gaseous  medium,  66. 


v.— THE  ORIGIN  OF  CRYSTALLINE  ROCKS  (pages  68-189). 

1.  Historical  and  Critical.  — Early  history;  Werner  and  Ilutton,  68. 
Neptunist  r^nd  vulcanist  schools,  76.    Modified  neptunism  of  Ij^s  la 


xu 


CONTENTS. 


Beche,  T7.  Sorope's  Theory  of  the  Earth,  81.  Huttonian  meta* 
morphism;  pseudomorphism  and  metasomatism,  82.  £ndopIu< 
tonic  hypothesis ;  two  igneous  magmas  imagined,  85.  Exoplutonic 
or  volcanic  hypothesis,  88.  Hydroplutonic  views  of  Scrope  and 
others,  96.  Metasomatic  hypothesis,  98.  The  various  hypotheses 
reviewed,  104. 

2.  Development  of  a  New  Hypothesis.  — Chemistry  of  the  prime- 

val earth;  a  solid  nucleus,  114.  Aqueous  origin  of  natural  silicates, 
119.  The  crenitic  hypothesis  formulated,  131.  Crenitic  rocks  and 
exoplutonic  rocks,  132. 

3.  Illustrations  of  the  Crenitic  Hypothesis.  —  History  of  zeo- 

litic  and  pectolitic  minerals,  135.  Secretions  of  basic  rocks,  138. 
Table  of  zeolites  and  related  species,  141.  Table  of  protoxyd-sili- 
cates,  145.  Action  of  heated  waters  on  glass,  147.  Recent  forma- 
tion of  zeolites,  150.  Artificial  production  of  zeolites,  feldspars, 
quartz,  etc.,  155.  Magnesian  silicates,  158.  Micas  and  tourma- 
»  lines,  160.  Finite  and  related  species,  163.  On  a  genetic  classifica- 
tion in  mineralogy,  166.  Studies  of  carbonates,  168.  Origin  of 
dolomites,  171.    Diageneois;  studies  of  crystallization,  173. 

4.  Conclusions.  —  The  crenitic  hypothesis  reviewed ;  magnesian  salts, 

176.  Exoplutonic  action;  folding  of  strata,  178.  Bock-decay,  its 
chemical  relations,  180.  Genesis  of  silicates  and  oxyds,  181. 
History  of  the  successive  groups  of  crystalline  schists,  183.  History 
of  exoplutonic  rocks,  186.  Relation  of  aqueous  to  igneous  agen- 
cies, 188. 


■  VI. —  THE  GENETIC  HISTORY  OP  CRYSTALLINE  ROCKS. 

(pages  190-245). 

Crystalline  Rocks  Defined,  191.  Crystalline  silicates  in  paleozoic 
rocks,  193.  Studies  of  glauconite,  196.  The  crenitic  hypothesis 
restated,  199. 

Origin  of  Stratiform  Structure,  200.  The  exoplutonists  on  the 
eruptive  origin  of  crystalline  schists,  201.  Non-plutonic  intrusion  of 
rock-masses,  204.  The  endoplutonic  hypothesis  of  the  origin  of  crys- 
talline schists,  205. 

Hypothesis  of  a  Liquid  Interior  of  tiie  Earth,  207.  Eliqua- 
tion  in  crystallizing  magmas,  208.  Illustrated  by  stratiform 
dolerites,  210.  Studies  of  chrysolitic  plutonic  rocks,  211.  Secular 
variation  in  the  composition  of  plutonic  rocks,  214.  Its  relations  to 
the  crenitic]hypothesis,  216.  Crystallization  from  artificial  fused  mag- 
mas, 219.  Intervention  of  water  in  eruptive  rocks;  igneo-aqueous 
fusion,  220  (and  :  15). 

Concretionary  Banded  Granites,  222.  Stratiform,  calcareous 
apatite-bearing  veins,  224.  Their  included  pyroxenic  and  feldspathic 
masses,  226.  Plutonic  hypothesis  of  the  origin  of  such  veins,  228 
(and  236).  Their  farther  geognostic  history,  and  their  mineralogy, 
229.     Studies  of   such  veins  in  Canada,  232.    Their  orighoi  not 


CONTENTS. 


xiii 


}nian  meta- 
£ndoplu- 
Exoplutonic 
Scrope  and 
;  hypotheses 

f  the  prime- 
iral  silicates, 
ic  rocks  and 

tory  of  reo- 
!  rocks,  138. 
)rotoxyd-sili- 
ecent  f  orma- 
is,  feldspars, 
Eind  tourma- 
tic  classifica- 
;.  Origin  of 
173. 

[nesian  salts, 
)ck-decay,  its 
oxyds,  181. 
183.  History 
jneous  ageu- 


ROCKS. 


in  paleozoic 

c  hypothesis 

i?j 

nists  on  the 

!  intrusion  of 

rigin  of  crys- 

■M 

!07.    Ellqua- 

*^ 

j   stratiform 

11.    Secular 

i  relations  to 

V 

I  fused  mag- 

neo-aqueous 

,   calcareous 

s 

i  feldspathic 

h  veins,  228 

mineralogy. 

origin  not 

plutonic,  but  aqueous,  236.  Calcareous  veins  and  beds  on  Lake 
Champlain,  237.  Crenitic  origin  of  such  veinstones,  238.  General 
corrugation  of  older  crystalline  roclcs  explained,  241.  Conclu- 
sions, 244. 

VII. -THE  DECAY  OP  CRYSTALLINE  ROCKS  (pages  240-278). 

Historical  Sketch,  246.  Views  of  the  writer  on  rock-decay  and 
boulders,  251.  Tlie  question  chemically  considered,  253.  Kouiuled 
masses  in  ancient  rocks,  254.  Rock-decay  in  Appalachian  crystalline 
schists,  256.  Its  relation  to  pyritous  deposits,  257.  Limonitcs  from 
pyrite  and  from  siderite,  261.  The  chemistry  of  iron-carbonate,  :i()6. 
The  decay  of  serpentines,  208.  Antiquity  of  rock-decay,  209,  Foriaa- 
tion  of  boulders  in  situ,  272.  Decay  in  tertiary  gravels  of  California, 
272.  Rock-decay  as  related  to  glacial  and  erosive  action,  274. 
Studies  in  Asia,  Scandinavia,  and  Corsica,  275.    Conclusions,  277. 

VIIL  — A  NATURAL  SYSTEM  IN  MINERALOGY  (pages  279-401). 

1.  Historical  Introduction.  —  Werner,  Mohs,  and  Jameson,  279. 
The  natural-history  method,  280.  The  chemical  method  of  Berze- 
lius  and  his  school,  282.    Defects  of  both  methods,  283. 

2..  Attempt  at  a  Natural  System.  —  Its  first  suggestion :  The 
Object  and  Method  of  Mineralogy,  285.  Equivalent  volumes,  288. 
The  law  of  progressive  series,  289.  Polymerism;  higli  molecular 
weights  and  homologies,  290.  An  atomic  notation ,  292.  The  con- 
.  ception  of  crystalline  mixtures,  294.  The  doctrine  of  polysilicates 
and  polycarbonates  restated,  298.  Isomerism  in  silicates;  physical 
and  chemical  differences,  299.  Atomic  or  quantivalent  formulas,  302. 
Unit-weights  and  unit-volumes,  303.  Principles  of  a  natural  system 
resumed,  304. 

3.  A  Classification  of  Silicates.  —  Three  sub-orders  of  silicates, 
305.  Chemical  relations  of  alumina  and  silica,  306.  Genetic 
history  of  Protosilicates,  Protopersilicates,  and  Persilicates,  307. 
Question  of  quantivalent  ratios,  311.  External  characters  of  spe- 
cies, 313.  Natural-history  orders,  Mica,  Gem,  Spar,  Zeolite;  col- 
loids, 314.  Division  of  sub-orders  into  tribes,  315.  Significance  of 
physical  and  of  chemical  characters,  318.  Atomic  symbols  and 
weights,  320.  General  view  of  tribes  and  species,  321.  Pectolitoids, 
with  table.  322.  Magnesian  species,  324.  Protospathoids,  with 
table,  327.  Protadamantoids,  with  table,  328.  Protophylloids,  with, 
table,  331.  Ophitoids,  with  ta'le,  332.  Zeolitolds,  with  table, 
•  334.  Protospathoids,  with  table  ^  336.  History  of  feldspars,  338. 
.  Scapolites,  340.  Sodalite,  cancriniio,  etc.,  343.  Protoperadaman- 
toids,  with  table,  345.  History  of  tourmalines,  with  table,  3.50. 
•  Protoperphyllolds,  with  table,  353.  Micas  and  chlorltes;  venerite, 
,  355.  Pinitoids,  with  table,  360.  Production  of  hydrous  colloids  by 
epigenesis;  pseudomorphism,  362.    Perzeolitoids  and  perspathoids; 


XIV 


CONTENTS. 


bismtithlc  species,  365.  Peradamantoids,  with  table,  365.  Zirconic 
species,  366.  Perpliylloids,  with  table,  367.  Argilloids,  with  table, 
369.  Crystalline  and  colloid  tribes,  373. 
4.  Classification  of  Othek  Species.  —  The  order  of  Oxydates,  and 
its  tribes;  unit-volumes,  376.  The  order  of  Metallates,  its  sub- 
orders and  tribes;  unit-volumes,  378.  The  orders  of  Haloidates  and 
Pyricaustates,  their  sub-orders  and  tribes,  380.  Notes  on  the  sys- 
tems of  Weisbach  and  Breithaupt,  381.  Tabular  view  of  classes  and 
orders  in  mineralogy,  383.  The  question  of  molecular  weights  and 
volumes,  383.  Polycarbonates,  polysilicates,  and  polytungstates,  etc., 
385.  Complex  inorganic  acids  of  Gibbs,  387.  An  advance  in  mineral 
chemistry,  389.  The  conception  of  chemical  units  and  unit-volumes, 
390.  Significance  of  specific  gravities,  394.  Relations  of  chemistry 
to  physics,  396.  Scope  of  mineralogy,  398.  Synoptical  tables  of  the 
three  sub-orders  of  silicates,  399. 

IX.  — HISTORY  OF  PRE-CAMBRIAN  ROCKS  (pages  402-425). 

1.  Pre-Cambrian  Rocks  in  North  America.  —The  names  Eozoic and 

Archaean,  402.  Early  studies  in  New  York  and  Canada;  Laurentlan 
and  Huronian  distinguished,  404.  Various  views  as  to  the  crystal- 
line schists  of  the  Atlantic  belt,  405.  The  petrosilex  group,  408. 
Relations  of  the  Huronian  or  pietre-verdi  series,  411.  The  Montal- 
ban  or  younger  gneissic  series,  411.  Ottawa  gneiss  and  Grenville 
series;  Lower  Laurentlan,  412.  Upper  Laurentlan,  liabradorian  or 
Norian,  413.  Lower  Taconic  or  Taconian,  in  part  confounded 
with  Huronian,  411.    The  Keweenian  series,  415. 

2.  Pre-Cambrian  Rocks  in  Europe.  —  Crystalline  schists  in  Wales, 

416.  Pebidian  and  Diraetian  groups,  417.  Arvonian  or  petrosilex 
group,  418.  Petrosilex-conglomerates  of  Wales  and  Massachusetts, 
420.  Various  crystalline  series  in  Great  Britain,  Ireland,  and  the 
Ardennes,  421.  Pebidian  referred  to  Huronian,  423.  Upper  Pe- 
bidian, Grampian  or  Montalban,  423.  Notice  of  a  recently  pro- 
posed scheme  of  classification,  424. 

X.— THE   GEOLOGICAL   HISTORY  OP   SERPENTINES,  WITH 
STUDIES  OF  PRE-CAMBRIAN  ROCKS  (pages  426-516). 

1.  Historical  Introduction.  —  Early  opinions  of  geologists,  427.    Ser- 

pentines as  of  aqueous  or  of  igneous  origin,  429.  Chemistry  of 
silicates  and  carbonates  of  lime  and  magnesia,  432. 

2.  Serpentines  in  North  America.  —  Laurentlan  serpentines;  Eo- 

zoon,  435.  Huronian  serpentines,  436.  Montalban  serpentines,  438. 
Serpentines  of  Pennsylvania  and  Manhattan  Island,  439.  Serpen- 
tines of  Staten  Island,  440.  Taconian  serpentines,  442.  Silurian 
serpentines  of  Syracuse,  443.    Sepiolite  and  talc,  448. 

3.  Serpentines  in  Europe.  —  Serpentines  and. greenstones  of  Corn- 

wall, 449.  Serpentines  and  ophiolites  of  Italy;  the  name  of  gabbro, 
451.    Studies  by  Italian  geologists;  their  different  views,  454. 


7 


CONTENTS. 


XV 


4.  Geology  or  the  Alps  and  Apennines,  — The  work  of  Gastaldl, 

458.  His  divisions  of  pre-Cainbrian  roclcs,  460.  Studies  in  tlie 
Biellese,  462.  Tlie  pietre-verdi  zone,  464.  Classification  of  Von 
Hauer;  older  gneiss;  pielre-terdi ;  younger  gneiss,  465.  Tlie 
lustrous  schists,  467.  The  St.  Gothard  section,  470.  Four  groups  of 
Alpine  pre-Cambrlan  rocks,  472.  The  succeeding  paleozoic  strata 
in  the  Alps  and  Apennines,  473.  Studies  in  Corsica,  Elba,  and  Sar- 
dinia, 474.  The  marbles  of  Carrara,  477.  Granulites  and  gneisses 
of  Saxony;  conglomerates,  478.  The  Montalban  series  defined  in 
1870,  480.  Concordant  views  of  Von  Hauer,  481.  Pre-Cambrian 
rocks  of  Bavaria,  481. 

5.  Sekpentines  of  Italy.  —  Gastaldi  on  their  age  and  stratigraphical 

relations,  483.  Serpentines  in  Liguria  and  Tuscany,  485.  Hydro- 
thermal  hypothesis  of  their  origin,  487.  The  serpentine  of  Monte- 
ferrato,  490.  Its  stratigraphical  relations,  404.  Studies  in  Liguria 
and  in  Lombardy,  406. 

6.  Genesis  of    Sekpentines.  —  Two  metasomatic   hypotheses,  497. 

The  metamorphic  and  the  hydroplutonic  hypothesis,  490.  Conclusions 
of  Dieulefait  regarding  serpentines,  501.  Other  magnesian  silicates, 
503.  Chrysolite  both  of  igneous  and  of  aqueous  origin,  506.  Studies 
of  chrysolitic  rocks,  507. 

7.  Geognostic  Relations  of  Serpentines.  —  Controversies  as  to 

aqueous  or  igneous  origin  of  British  serpentines,  510.  Stapff  on  the 
serpentines  of  St.  Cothard,  511.  The  non-plutonic  intrusion  of 
rocks,  512.    Conclusions,  514. 


XI.— THE  TACONIC  QUESTION  IN  GEOLOGY  (pages  517-616). 

1.  Introduction. —Amos  Eaton;  hi.,  threefold  division  of  strata,  518. 

Primitive  Quartz-rock  and  Lime-rock;  Transition  Argillite,  First 
Graywacke  and  Sparry  Lime-rock,  519.    Second  Graywacke,  520. 

2.  The  Geological  Survey  of  New  York.  —  Ebenezer  Emmons; 

The  Champlain  division,  522.  The  Taconic  system,  523.  Mather; 
he  confounds  the  First  and  Second  Graywackes,  523.  Vanuxem; 
the  Hudson-River  group,  524.  Eaton's  farther  conclusions,  526. 
The  term  Ordovician,  528,  Tabular  view  of  Eaton's  classification, 
529.    Relations  of  various  pre-Cambrian  rocks,  530. 

3.  Geological  Studies  in  Pennsylvania. —  The  central  valleys, 

631.  Classification  of  H.  D.  Rogers,  5S4.  His  Primal  and  Auroral  are 
Lower  Taconic;  their  mineralogy,  535.  Their  great  thickness,  537. 
The  First  Graywacke  in  Pennsylvania,  539.  The  Lower  Primal  or 
Azoic  and  the  Hypozoic  series  of  Roger"",  544.  Petrosilex  or 
Arvonian  In  Pennsylvania  and  elsewhere,  o46.  Lower  Taconic  in 
Chester,  Lancaster,  and  York  Counties,  549.  The  South  Mountain, 
and  a  second  Laurentian  axis,  649.  Iron  ores  of  the  Primal  and 
Auroral;  the  mines  at  Cornwall,  Dillsburg,  etc.,  550. 

4.  LovrER  Taconic  in  Various  Regions, —The  Taconic  hills;  the 

Stockbridge  limestone,  554.     Argillites,  G55.     Lower  Taconic  in 


XVI 


CONTENTS. 


Virginia,  556.  Its  extension  from  the  Schuylkill  Into  North  Caro- 
lina described  by  Maclure,  557.  Five  areas  of  it  in  North  Carolina, 
558.  Flexible  sandstone  or  itacolumite,  501.  Lower  Taconic  in 
South  Carolina,  Georgia,  and  Alabama;  pyrophyllite,  rutile,  and 
diamonds,  503.  Lleber  on  the  Itacolumite  series  of  King's  Moun- 
tain, South  Carolina,  504.  He  compares  it  with  the  diamond- 
bearing  rocks  of  Brazil  and  Ilindostan,  564.  Mineralogy  of  the 
Lower  Taconic,  5(^.  Henry  Wurtz  on  these  rocks  in  North  Caro- 
lina, 560.  Lower  Taconic  east  of  the  Appalachian  valley,  in  New 
Jersey,  Rhode  Island,  Maine,  New  Brunswick,  and  Nova  Scotia,  570. 
In  Ontario;  the  Hastings  series,  674.  Lower  Taconic  on  Lake 
Superior;  the  Animlkie  series,  578.  Distinguished  from  Huronian; 
studies  by  Kominger,  580.  The  name  Taconian  proposed,  582. 
Relations  of  Taconian  to  eozoic  and  paleozoic  times,  583. 

5.  Uppeu  Taconic  or  First  Graywacke.  — Traced  from  the  Hudson 

to  the  lower  St.  Lawrence,  584.  The  Upper  Taconic  or  Taconic- 
slate  group,  defined  by  Emmons  in  1842,  and  then  included  in  the 
Silurian  system.  580.  Its  relations  to  the  Champlain  division; 
Lower  and  Upper  Taconic  farther  distinguished,  588.  Upper 
Taconic  in  Pennsylvania,  589.  The  Green-Pond  Mountain  belt,  590. 
Upper  Taconic  in  eastern  New  York;  its  apparent  inversion  by 
parallel  faults,  592.    Red  Sand-rock  of  Vermont,  593. 

6.  Upper  Taconic  in   Canada.  —  History  of  the  so-called  Quebec 

group,  594.  An  inverted  series  at  Quebec,  690.  Stratigraphical 
breaks,  598.  Studies  in  the  Ottawa  basin,  599.  Relations  of  the 
Ordovician  limestones,  600.  James  Hall  on  the  Hudson-River 
group.  601.  Logan  on  the  Cambrian  or  First  Graywacke  in  New 
York,  603.  Distribution  of  Ordovician  and  Silurian  along  the 
Cambrian  belt,  604.  The  First  Graywacke  or  Uppei  Taconic 
with  the  Sparry  Lime-rock,  is  the  Hudson-River  group,  607.  The 
copper-bearing  sandstones  and  amygdaloids  of  Lake  Superior,  called 
Quebec  group  by  Logan,  610.  Their  history,  611.  They  are  named 
Keweenian,  614.    A  similar  series  in  Arizona  and  Texas,  616. 

7.  North  American  Paleozoic  History.  —  The  Eozoic  lands  and  the 

Cambrian  sea,  616.  First  or  Cambrian  Graywacke,  617.  The 
Ordovician  sea,  618.  The  Green  Mountains  and  White  Mountains, 
620.    Keweenian  and  Cambrian  series;  Movements  of  strata,  621. 

8.  The  Taconic  History  Revieaved.  — American  Cambrian  in  differ- 

ent areas  compared,  622.  Rocks  of  Grand  Caflon  group  and  of 
Newfoundland,  624.  The  Taconic  system  named,  627.  First 
Graywacke  or  Taconic  slate-group  and  Sparry  Lime-rock,  627. 
Mather  and  his  liypothesis,  628.  Speculations  of  various  observers, 
630.  First  Graywacke  or  Upper  Taconic  called  Hudson-River 
group,  and,  later,  Quebec  group,  633.  Its  Cambrian  age,  635. 
Farther  studies  of  the  First  Graywacke  series,  638.  J.  D.  Dana  on 
the  Taconic  question,  642.  The  Taconic  succession  defined  by 
Emmons,  643.  The  Sparry  Lime-rock  is  Upper  Taconic,  645.  Five 
unlike  views  as  to  Lower  Taconic  or  Taconian,  648.    Distribution 


CONTENTS. 


XVU 


of  Taconlan  In  North  Amorica,  fl.'0.  Confonmllnjr  the  First  and 
Second  Graywackes;  a  great  error  in  American  stratigraphy,  653. 

9.  The  Metamoki'IIIc  IIyi'otiie8I9.  —  Tlie  teachings  of  Mather,  655. 

Views  of  II.  I),  and  W.  B.  Rogers,  657.     J.  D.  Dana  and  others  oh 
Soutlieastern  New  York,  66;}.     Rise  and  fall  of  llie  doctrine  of  nieta- 
'  morijliism,  668.    rre-Cambrian  age  of  the  Scottish  Highlands,  669. 

10.  Conclusions. —  The    Lower    Taconic,  Taconian,    or   Itacolumitic 

series;  its  mineralogy,  674.  Its  distribution  in  North  America,  675. 
The  Upper  T  ;oidc.  First  or  Cambrian  Graywacke,  IIudscn-River 
group,  or  Quebec  group,  676.  Relations  of  various  crystalline 
series,  678.  Taconian  in  the  West  Indies,  South  America,  and 
elsewhere,  680. 

APPENDIX. 

MiNEBALOGicAL   CLASSIFICATION ;   action   of  fluorhydric  acid,  687. 
Binomial  nomenclature  ;  mineralogical  evolution,  688. 


POSTSCEIPTUM. 

In  discussing  the  "  Question  of  Molecular  Weights,"  on  pages  383-395 
of  this  book,  it  is  said  that  while  solid  species  must  be  regarded  as  poly- 
merids,  and  their  molecular  weight  as  some  multiple  of  the  unit-weight 
deduced  from  chemical  analysis,  "  the  molecular  weights  of  these  are  as 
yet  unknown";  and,  moreover,  that  "the  relations  alike  of  this  unit- 
weight  and  unit-volume  to  those  of  the  molecule  to  which  it  belongs  are 
unknown."  From  the  principles  stated  on  those  pages,  and  farther  on 
pages  284-304,  we  may,  however,  readily  fix  the  weights  of  these  poly- 
merids  if  we  consider  that  the  volume,  Instead  of  being  an  arbitrary  quan- 
tity, is  the  unit  adopted  in  the  chemistry  of  gases  and  vapors;  and,  more- 
over, that  the  law  of  volumes  is  not  limited  to  tliese,  but  is  universal,  and 
applies  equally  to  their  condensation  into  liquids  and  solids,  which  are 
different  polymerids  of  their  corresponding  vapors,  —  the  conversion  of 
gases  into  liquids  and  solids,  and,  convcrP"'y»  the  vaporization  of  these, 
being  a  chemical  process.  If  we  take  as  the  unit  the  voiume  of  water- 
vapor  (H^O  =  18)  at  100°  C,  we  find  that  1487  volumes  of  this  are  con- 
densed into  one  volume  of  ice  at  0°  C,  with  a  specific  gravity  of  0.9167, 
80  that  the  molecular  weight  —  or,  strictly  speaking,  the  equivalent 
weight— of  ice  is  1487  x  18  =  26,766;  wliile  water  is  1628(H20)  =  29,304. 
This  quantity  being  the  equivalent  weight  of  water  (which  is  the  species 
adopted  as  the  unit  of  specific  gravity  for  liquids  and  solids),  shows,  when 
divided  by  two,  the  number  of  times  that  the  weight  of  the  hydrogen  vol- 
ume, Hj,  is  contained  in  one  volume  of  that  unit.  From  it  we  calculate 
the  equivalent  weight  and  the  true  chemical  formula  of  any  liquid  or  solid 
species,  when  its  specific  gravity  (water  =  1.000)  and  its  empirical  formula 
are  known. 

The  so-called  volume  of  the  chemical  unit,  atom  or  molecule  is  the 
reciprocal  of  its  coetlicient  of  condensation. 


/ 


NATURE  m  THOUGHT  AND  LANG o AGE. 


This  Essay  was  presented  and  read  in  abstract  to  the  National  Academy  of 
Sciences  at  WusUlngton,  April  18,  1881.  Privately  printed  in  June,  it  was  publislied 
in  the  London,  Edinburgh  and  Dublin  Philosophical  Magazine  for  October,  1881  ([V] 
xli.,  233-263)  under  the  title  of  The  Domain  of  Physiology,  or  Nature  in  Thought 
and  Language,  and  again  in  a  second  edition,  separately,  by  S,  K.  Cassiuo,  Boston, 
in  1882. 

I.  —  HISTORICAL. 

§  1.  The  importance  of  a  correct  and  well-defined  ter- 
minology in  science  cannot  be  overestimated,  since  a  want 
of  precision  in  language  leads  to  vagueness  in  thought, 
and  often  to  errors  in  philosophy.  There  are.  few  more 
striking  examples  of  indefiniteness  in  language  than  can 
be  found  in  the  use  of  the  words  physic,  physiology,  and 
their  derivatives.  The  material  universe  is  designated 
with  etymological  correctness  as  physical,  that  is  to  say, 
natural  —  a  term  which  belongs  alike  to  the  organic  and 
the  mineral  kingdoms ;  but  in  the  use  of  this  and  of  other 
words  having  a  similar  etymology  (Gr.  (pi'>atg,  Lat.  natura) 
we  find  in  modern  language  many  restrictions,  limitations, 
and  ambiguities.  It  will  aid  us  in  our  present  inquiry  if 
we  bear  in  mind  that  both  the  Greek  physis  and  the 
Latin  natura  involve  the  notion  of  a  generation  or 
growth,  and  that  the  adjectives  physical  and  natural,  in 
their  origin,  imply  the  results  of  a  formative  process  or 
evolution.  The  term  physia  (wjiich  we  translate  by 
nature),  as  employed  by  Aristotle,  denotes  that  which  ia 
at  once  self-producing,  self-determined,  and  uniform  in  its 
mode  of  action. 

§  2.  The  substantive  physic  (fuatx^,  physica,  physique), 
has  been  employed  by  philosophers  since  the  time  of  Aris- 
totle to  signify  the  knowledge  of  all  material  nature. 


2 


NATUUE    IN   THOU(aiT   AND   LANOUAOE. 


[L 


"  Physical  science,"  as  well  defined  by  Clerk  Maxwell  at 
the  beginning  of  his  little  treatise  on  Matter  and  Motion, 
"is  tliat  department  of  knowledge  whicii  relates  to  the 
order  of  nature,  or  in  other  words,  to  the  reguhir  succes- 
sion of  events.  The  name  of  piiysical  science,  however,  is 
often  applied,  in  a  more  or  less  restricted  manner,  to  tliose 
branches  of  science  in  which  the  phenomena  aie  of  the  sim- 
plest and  most  abstract  kind,  excluding  the  consideration 
of  the  more  c()m])lex  phenomena  such  as  are  observed  in 
livint;  beings." 

§  3.  To  the  student  of  natural  phenomena,  Aris- 
totle gave  the  names  of  tpvaix6i  and  qivalokoyoi.  These 
words  were  adopted  in  the  same  sens  3  by  the  Romans, 
who  made  use  of  the  substantives  phyaicus  and  physioln. 
gia  to  designate  natural  philosophers  and  natural  science. 
Cicero  writes  of  the  physicus  or  physician  Anaxagoras, 
g,nd  employs  the  word  physiology  to  denote  "  the  science 
of  natural  things,"  ill  accordance,  as  he  tells  us,  with 
Greek  usage.* 

§  4.  The  earlier  English  writers  followed  the  Greek 
and  Latin  usage,  and  employed  the  substantive  physic  (or 
physike)  in  the  same  sense  as  Aristotle.  Thus,  in  the  four- 
teenth century,  Gower  defines  physic  as  that  part  of  phi- 
losophy which  teaches  the  knowledge  of  material  things, 
the  nature  and  the  circumstances  of  man,  animals,  plants, 
stones,  and  everything  that  has  bodily  substance.f     Des- 

*  Cicero,  Varr.  lib.  I.  R.  R.  cap.  40.  "  Si  sunt  somlna  in  afire,  ut 
ait  physicus  Anaxagoras";  also  De  Nat.  Deorum,  I,  4.  "Rationem 
naturae  quam  pliysiologiam  Graeci  appellant."  In"  the  Totius  Latlni- 
tatis  Lexicon  of  Facciolatus  and  Forcellinus  we  find  the  definition  : 
Physiologia,  scientia  quae  de  naturis  rerum  disserit,  eadem  ac  Physica. 

t  Gower,  dividing  theoretical  philosophy  into  three  parts,  Theologia, 
Physica,  and  Mathematica,  tells  us  :  — 

"Physike  is  after  the  seconde, 
Thi-oiigU  which  the  philosopbre  hath  fonde,    •  '  ;.    ^. 

To  teche  sondrle  kuowlechyngea  __     , 

Upon  the  bodeliches  thinges 
Of  man,  of  beast,  of  herb,  of  stone,        •    . 
Of  flsh,  of  fowl,  of  euerlch  one 
That  be  of  bodily  substance, 
The  nature  and  the  circumstance." 
/|  CONFESSio  Amantis,  book  Tii. 


\ 


t.l 


NATURE  IN  THOUGHT  AND  LAXQUAOE. 


cartes,  in  tlie  sovonteenth  century,  employed  the  word  (in 
French  phi/siqiie^  witli  the  same  signification,  and  it  wast 
Buhsetiuently  used  by  Locke  in  a  still  more  comprehensive 
sense.  He  writes  of  "the  knowledge  of  things  us  they 
are  in  tlieir  own  proper  beings,  their  ct)nstitution8,  prof)- 
ertics,  and  oi)erationa ;  whereby  I  mean  not  only  matter 
and  body,  but  spirits  also,  which  havq  their  proper  natures, 
constitutions,  and  operations,  as  well  as  bodies.  This,  in 
a  little  more  enlarged  sense  of  the  word,  I  call  (pvamfi  or 
natural  philosophy."  * 

§  6.  We  have  seen  that  in  Latin  the  words  physic  and 
physiology  were  used  synonymously.  That  they  were 
thus  understood  Ijy  English  writers  is  apparent  from  the 
Universal  English  Dictionary  of  Edward  Phillips  ((!th 
edition,  170G),  where  Physiology  is  defined  as  "  a  discourse 
on  natural  things ;  physics  or  riatural  jihilosopliy ;  being 
either  general,  that  relates  to  the  affections  or  properties 
of  matter,  or  else  special  and  particular,  which  considers 
matter  as  formed  or  distinguished  into  such  and  such  sjje- 
cies."  Cotgrave,  a  lexicographer  of  the  seventeenth  cen- 
tury, in  his  "  French  and  English  Dictionary,"  also  defines 
Physiologie  as  "a  reasoning,  disputing,  or  searching-out  of 
the  nature  of  things,"  a  definition  which  is  cited  by  Charles 
Richardson  in  his  English  Dictionary,  under  Physiology. 

§  6.  It  was  to  those  who  occupied  themselves  with  ab- 
stract or  general  physiology  (as  defined  by  Phillips)  that 
the  Greeks  gave  the  name  of  physiologists,  first  applied  to 
the  philosophers  of  the  Ionian  school,  who  sought  to  de- 
rive all  things  from  one  or  more  material  elements,  and 
thus  had  a  physical  basis  for  their  system  of  the  universe, 
as  distinguished  from  the  school  of  Pythagoras,  whose 
system  was  based  on  numbers  and  forms.  Of  Empedocles, 
the  author  of  a  didactic  poem  on  Nature  in  which  we  first 
find  enunciated  the  doctrine  of  the  four  elements,  fire,  air, 
earth,  and  water,  Aristotle,  in  his  Poetics,  makes  the  criti- 
cism that  he  was  mors   of  a  physiologist  than  a  poet. 

*  Human  Understanding,  b.  vii.,  c.  21. 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


VL 


Humboldt  repeatedly  employs  the  word  physiology  and 
its  derivatives  in  the  same  general  sense.  Thus,  he  writes 
of  "the  natural  philosophy  of  the  Ionian  physiologists" 
(physiologien),  which  "was  devoted  to  the  fundamen- 
tal ground  of  origin,  and  the  metamorphoses  of  one 
sole  element  "  ;  of  the  "  physiological  fancies  of  the  Ionian 
school,"  and  of  the  teachings  of  Anaxagoras  of  Clazomenae, 
"  in  the  latter  period  of  development  of  the  Ionian  physi- 
ology." *  Of  Anaxagoras  it  may  be  observed  that  his 
views  marked  a  great  advance  over  those  of  his  predeces- 
sors, and  that  he  merited  the  encomium  pronounced  by 
Aristotle  that  he  was  the  first  philosopher  who  had 
written  soberly  of  nature. 

§  7.  We  find  the  word  physiology  and  its  derivatives 
employed  in  the  same  general  sense  by  English  writers  in 
the  seventeenth  century.  Thus,  Cudworth  speaks  of  "  the 
old  physiologers  before  Aristotle,"  and  writes  "  they  who 
first  theologized  did  physiologize  after  this  maixner,  inas- 
much as  they  made  the  Ocean  and  Tethys  to  have  been 
the  original  of  generation,"  f  while  Henry  Moore  says, 
"  It  will  necessarily  follow  that  the  Mosaical  philosophy, 
in  the  physiological  part  of  it,  is  the  same  with  the  Carte- 
sian." I  Coming  down  to  later  writers,  we  find  the  word 
physiologist  used  in  a  general  sense,  as  equivalent  to  our 
modern  term  naturalist.  Thus,  Dugald  Stewart  calls 
Cuvier  "  the  most  eminent  and  original  physiologist  of  the 
present  age,"  and  Burke  writes,  "The  national  menagerie 
is  collected  by  the  first  physiologists  of  the  time."  § 

We  may  note  in  this  connection  the  two  series  of  abridg- 
ments of  the  Philosophical  Transactions  of  the  Royal  Soci- 
ety—  the  first,  from  its  commencement  to  ITOO,  and  the 
second  to  1720 — both  published  with  the  imprimatur  of 
Newton  as  president  of  the  Society.     In  these  collections 

*  Cosmos,  Otte's  translation,  Harper's  ed.,  II.,  108,  and  III.,  11. 
t  Intellectual  System,  pp.  120,  171. 
t  Philosophical  Cabbala,  Appendix,  c.  1. 

§  Stewart,  Philosophy  of  the  Human  Mind,  II.,  c.  4;  and  Burke, 
Letter  to  a  Noble  Lord. 


I   \ 


f    -Am 
IE.                 jM 

gy  and            M 

;  writes            ,^^H 

ogists '             .1^9 

idamen-           mM 

of    one           '^1 

3  Ionian           ;^B 
omenae,           |^ 

n  physi-           M 

that  his           S 

3redeces-           ^| 

meed  by          « 

vho    had           ^^H 

jrivatives          |B 

jrriters  in           |9 

:s  of  "  the          M 

they  who          H 

iner,  iuas-           9 

lave  been          9 

)ore  says,          ^ 

lilosophy,             1 

he  Carte-           C- 

the  word          j| 

nt  to  our         m 

^art  calls         ■ 

rist  of  the 

nenagerie 

"  § 

of  abndg- 

oyal  Soci- 

,  and  the 

imatur  of         M 

loUections        B 

L] 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


In.,  11. 


and  Burke, 


the  classification  of  the  papers  is  as  follows :  (1)  "  Matlie- 
matical,"  including  pure  and  applied  mathematics ;  (2) 
"Physiological,"  embracing  all  meteorological  phenom- 
ena, tides,  terrestrial  magnetism,  mineralogy,  geolog}-, 
botany,  zoology,  and  the  study  of  the  physical  wrrld  in 
general.  Subjects  relating  to  the  human  body,  liowever, 
such  as  anatomy  and  medicine,  were  excluded  from  part 
2,  and,  with  chemistry,  made  a  first  division  of  part  3,  in 
the  second  and  last  division  of  which  were  included  philo- 
logical and  miscellaneous  papers. 

§  8.  Of  the  "  special  and  particular  physiology,"  as 
distinguished  by  Phillips,  we  have  an  example  in  Glanvil, 
who,  in  the  seventeenth  century,  writes  of  the  physiology 
of  comets.*  The  citation  from  Burke,  identifying  physi- 
ologists with  zoologists,  may  also  perhaps  be  taken  as  an 
example  of  a  special  use  of  the  word,  wliile  in  later  times 
we  have  come  to  speak  of  Vegetable  Physiology,  Animal 
Physiology,  Human  Physiology,  and  even  of  Jiental  Phys- 
iology, a  term  employed  by  Dr.  Thomas  Brown  of  Edin- 
burgh,! who  speaks  of  "  physiology  corporeal  or  mental."  J 

*  "So  that  we  need  not  be  appalled  at  blazing  stars,  and  a  comet  is 
no  more  ground  for  astrological  presages  than  a  flaming  chimney.  The 
unparalleled  Descartes  hath  unravelled  their  dark  physiology,  and  to 
wonder  solved  their  motions."  Joseph  Glanvil,  Scepsis  Scientifica,  .  .  . 
an  Essay  on  the  Vanity  o*  Dogmatizing,  1665,  c.  xx. 

t  The  grounds  upon  which  Brown  based  this  extension  of  the  term 
physiology  may  be  gathered  from  the  following  passages:  "  There  is,  in 
short,  a  science  which  may  be  called  mental  physiology,  as  there  is  a 
science  relating  to  tlie  structure  and  offices  of  our  corporeal  frame,  to 
which  tiie  term  physiology  is  more  commonly  applied."  He  farther 
speaks  of  the  ^'physiology  of  the  mind,  considered  as  a  substance  capable 
of  the  various  modifications  or  states  which,  as  they  succeed  each  other, 
constitute  the  phenomena  of  thought  and  feeling,"  and  declares  that 
"the  mind  is  as  an  object  of  study  ...  to  be  compreliended,  with  every 
other  existing  substance,  in  a  syi^tem  of  general  i^hysics,"  Brown,  The 
Philosopliy  of  the  Human  Mind,  lectures  I.,  II.,  and  V. 

t  Since  the  writing  of  this  essay,  Prof.  Osborne  Reynolds,  in  Nature 
for  June  9,  1881  (vol.  xxiv,  page  123),  has  made  a  happy  use  of  the  word 
in  question  in  Avriting  of  the  locomotive  engine  of  George  Stephenson,  of 
which  he  says,  "the  physiology  of  the  machine  resembled  that  of  the 
human  system";  while  he  speaks  of  its  inventor  as  "he  who  produced 
the  locomotive  physiologically  perfect." 


rz^ 


NATUKE  IN  THOUGHT  AND  LANGUAGE. 


tl. 


§  9.  There  is  an  example  of  a  special  application  of  the 
words  physiology  and  physic  which  requires  farther  con- 
sideration. We  have  already  cited  Cotgrave's  first  defini- 
tion of  the  word  Physiologic,  to  which  he  adds,  as  a  sec- 
ondary meaning,  "anatomizing  physiv.,  or  that  part  6f 
physic  which  treats  of  the  composition  or  structure  of 
man's  frame."  In  more  recent  times,  however,  the  term 
has  come  to  mean,  not  the  anatomy,  composition,  or  struc- 
ture of  the  human  frame,  but  its  functions,  to  which  sig- 
nification physiology  is,  in  popular  language,  limited, 
though  now  by  didactic  writers  extended  to  include  the 
functions  of  the  lower  animals,  of  plants,  and  even  of  the 
human  mind. 

The  word  physic,  as  we  have  seen,  was  used  by  Gower 
in  the  general  sense  cf  a  knowledge  of  all  •  aaterial  things, 
but  his  contemporary,  Chaucer,  employed  it,  in  a  special 
and  restricted  sense,  to  designate  the  science  of  medicine. 
Thus,  he  calls  his  practitioner  of  the  medical  art  "  a  doc- 
tor of  physic,"  and  in  his  tiescription  of  this  personage 
adds  that  "  gold  in  physic  is  a  cordial."  *  Subsequently, 
and  to  our  own  time,  we  find  the  terra  applied,  in  Chau- 

•  "With  us  there  was  a  doctour  of  phisik, 
In  all  the  world  ne  was  there  non  him  lyk 
To  speke  of  phisik  and  of  surgerye, 
For  he  was  grounded  in  astronomye. 

■  •  •  •  ■ 

He  knew  the  cruse  of  every  maladye, 
Were  it  of  hot  or  cold  or  moyste  or  drye, 
And  where  engendered  and  of  what  h'umoure; 
He  was  a  very  parfight  practisour. 


I     I 


Well  knew  he  the  old  Esculapius, 
And  Dioccorides,  and  eke  Rufus, 
Old  Ilippocras,  Kali  and  Gallien, 
Serapion,  Rasis  and  Avicen, 
Averrois,  Damascene  and  Constantin, 
Bernard,  and  Gatisden  and  Gilbertin. 

For  gold  in  phisik  is  a  cordial. 
Therefore  he  loved  gold  in  special." 

CuAucEB,  Canterbury  Tales,  Prologue, 


I] 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


cer's  sense,  alike  to  the  art  of  healing  and  to  its  medica- 
ments. If  we  search  for  the  origin  of  this  peculiar  use 
of  the  word  physic,  we  shall  find  it  employed  with  the 
same  meaning  in  medieval  Latin.*  In  French  also,  ac- 
cording to  Littr^,  the  term  physique  was  in  the  thirteenth 
century  applied  to  the  science  of  medicine,  the  professors 
of  which  were  tlien  called  phi/siciens,  |  a  designation  which 
they  kept  till  the  time  of  Rabelais,  and,  as  we  know,  still 
retain  in  English,  though  the  term  physicien  is  at  present 
applied  in  French  only  to  students  of  physical  science  in 
the  restricted  sense  mentioned  in  §  2,  including  what,  in 
didactic  phrase,  is  now  called  physique  in  French  and 
physics  in  English. 

§  10.  It  is  a  curious  inquiry  how  these  terms  came  to 
have  this  restricted  use  in  the  middle  ages,  and  how  the 
name  of  physicus  or  physician,  originally  applied  to  the 
student  of  material  things  —  and  by  pre-eminence  to  An- 
axagoras  of  Clazcmenae,  who  was  called  "the  ph}sician," 
(6  <pvaix6i')  —  came  to  signify  in  medieval  France  and  Eng- 
land the  medieus,  mSdecin,  or  mediciner  —  the  master  of 
the  art  of  healing  diseases  in  the  human  frame.  Menage 
assigns  as  a  reason  for  this,  that  the  art  "  consists  princi- 
pally in  the  contemplation  of  nature,"  and  in  this  imper- 
fect statement  will  be  found  the  answer  to  our  inquiry, 
upon  which  much  light  is  thrown  by  the  use,  in  medieval 
times,  of  the  words  naturien  and  naturiste.     Naturien,X 


*  Du  Cange,  Glossarium  ad  Scriptores  mediae  et  iriflmae  Latinitatis; 
ed.  Ilenschel,  sub  voce  Physica. 

t  "  Nous  etablissons  .  .  un  fisicien  jure  et  pensionnaire  du  couvent." 
Reglement  de  I'Abbaye  Royale  de  Soissons,  A.  D.  1282;  cited  by  Menage, 
Dictionnaire  Etymologique,  sub  voce  Physicien. 

X  Tlie  following  satirical  rhyme  of  the  fourteenth  century  is  cited  by 
Littre,  in  his  Dictionnaire,  sub  voce  Naturien,  — 

Oil  le  physicien  fait  tin,  Li  commence  le  mddecln, 
Supposant  pour  pbyslclen,  Lo  trfes-savant  naturien. 

•  Gower,  who  uses  the  word  more  than  once,  writes,  — 

And  thus  seyth  the  naturien, 
Which  is  an  astronomien. 

CONFESSio  Amantis,  book  vil. 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


m 


which  is  found  in  the  fourteenth  century,  both  in  English 
and  in  French,  is  etymologically  equivalent  to  physicien, 
and  was  ai^plied  to  certain  professors  of  the  art  of  healing, 
being  apparently  synonymous  with  naturiste,  which,  as 
stated  by  tlie  learned  Littrd,  in  his  Dictionnaire,  meant 
"  a  medicuier  who  practised  expectant  medicine,"  that  is 
to  say,  who  trusted  to  the  conservative  influences  of  nature 
to  heal  his  patient. 

§  11.  For  the  origin  of  the  physician  or  naturian  in 
medicine,  we  must  go  back  more  than  twenty  centuries  to 
the  great  Hippocrates,  justly  styled  the  father  of  medicine. 
It  was  a  maxim  of  his  school  that  "  nature  is  the  healer  of 
diseases,"  *  and  himself  it  was  who  wrote  of  medicine  that 
"  the  art  consists  in  three  things,  the  malady,  the  patient, 
and  the  mediciner.  The  mediciner  is  the  servant  of  na- 
ture, and  the  patient  must  help  the  mediciner  to  combat 
the  disease."! 

Nature,  in  the  language  of  the  time,  was  spoken  of  as  a 
vis  medieatrix,  or  healing  power ;  but  Virchow  justly  re- 
marks that  from  a  careful  perusal  of  the  works  left  us  by 
the  great  master,  we  cannot  doubt  that  by  nature  he 
meant  the  whole  bodily  constitution  of  man.  Hippocrates 
insisted  iipon  a  treatment  of  diseprco  based  not  upon 
magic  nor  upon  supernatural  agencies,  but  upon  the  be- 
lief that  nature  works  according  to  a  divine  necessity. 
In  other  words,  he  taught  a  system  of  pathology  founded 
on  the  recognition  of  physical'  laws,  .v^hich  he  opposed  to 
the  superstitious  notions  of  his  caste  and  his  age.  The 
iatros,  or  mediciner,  was  henceforth  no  longer  a  magician, 
nor  a  priest,   but  a  physiologist,   physician,  or  naturist, 

»  Nova&v  ffisiBS  IrjTQol.     Hippocrates,  Epidem.,  book  VI.,  sec.  5,  1. 

t  Epidem.,  boolc  I.,  sec.  2,  5.  The  received  text  makes  the  mediciner 
"the  servant  of  tlie  art,"  but  Galen,  in  his  Commentary,  tells  us  that 
some  manuscripts  in  his  time  had,  instead  of  6  IrjTQdg  intjQhtjg  xijf  rixv^St 
the  virord  cpiaeme  for  jixvrjg.  This  latter  reading  I  have  followed  as  more 
cons'  lant  with  the  previously  cited  dictui^i,  for  if  "nature  is  the  healer 
of  diseases,"  the  mediciner  must  be  "the  servant  of  nature."  uee 
Adams's  Genuine  Works  of  Hippocrates,  vol.  i.,  p.  360,  note;  also  Littr^'s 
Hippocrates,  vol.  ii.,  in  loco. 


tl 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


1 


seeking  for  healing  agencies  in  the  study  of  tlie  physical 
organization  of  the  patient.  The  pathology  of  the  Dog- 
matists, who  were  the  disciples  of  Hippocrates,  was  based 
upon  a  knowledge  of  the  structure  and  functions  of  the 
human  organism,  and  of  the  structural  and  functional 
modifications  produced  alike  by  disease  and  by  the  action 
of  drugs. 

§  12.  But  Hippocrates  had  still  another  claim  to  the 
title  of  physician,  or  physiologist,  since,  not  content  with 
studying  the  physical  constitution  of  man,  he  insisted  upon 
the  importance  of  a  knowledge  of  all  his  relations  to 
external  nature.  In  Ms  celebrated  treatise  "  On  Airs, 
Waters,  and  Localities,"  Hippocrates  declares  that  who- 
ever would  understand  medicine  must  study  the  move- 
ments of  the  heavenly  bodies,  and  all  meteorological  phe- 
nomena, together  with  physical  geography,  including 
climate,  soil,  vegetation,  rocks,  minerals,  and  watei'S ;  to 
which  he  a,dds  that  the  mediciner,  if  he  wou^.d  preserve 
the  health  of  his  patients,  and  succeed  in  his  art,  must 
investigate  "  everything  else  in  nature."  * 

§  13.  The  teachings  of  Hippocrates  and  his  followers 
were  maintained  in  the  school  of  Alexandria,  where,  we 
are  told,  the  studies  were  arranged  in  four  divisions  or 
faculties :  letters,  mathematics,  astronomy,  and  medicine ; 
under  which  last,  as  we  know  from  the  history  of  the  Mu- 
seum, were  included  botany,  geology,  chemistry,  optics, 
and  mechanics.  The  learning  of  the  Alexandrian  school 
was  preserved  by  the  Jews  and  the  Nestorians,  and  by 
them  handed  down  to  the  Arabians,  who  brought  it  with 
them  into  southern  Europe.  It  suffices  to  speak  of  Djafar, 
Rhazes,  Avicenna,  and,  later,  of  the  schools  of  Salerno, 
Cordova,  Montpellier,  Narbonne,  and  Aries,  where  were 
gathered  together  men  famed  alike  in  medicine,  anatomy, 
zoology,  botany,  optics,  mechanics,  and  astronomy,  who 
merited  in  the  widest  sense  the  name  which  they  then 


*  Hippocrates  "On  Airs,  Waters,  and  Localities";  sections  1-8. 


iiiLaij!iiiaiu«J!!iM« 


10 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


IT. 


ml 


il:i 


bore,  of  physicians ;  since  they  were  not  simply  iatro- 
physicians,  but  philosophers  who  had  takeu  all  natural 
science  for  their  province.  Draper,  speaking  of  the  Ara- 
bians of  that  age,  says,  "  Their  physicians  were  their  great 
philosophers ;  their  medical  colleges  were  their  foci  of 
learning.  Arab  science  emerged  out  of  medicine,  and 
in  its  cultivation  physicians  took  the  lead,  its  beginnings 
being  in  the  pursuit  of  alchemy."  *  It  is  to  be  noted  that 
Chaucer's  doctor  of  physic  (§  9)  was  not  only  learned  in 
astronomy,  and  read  in  the  works  of  the  Greeks,  Hippoc- 
rates, Galen,  llufus,  and  Dioscorides,  but  knew  well  those 
of  Ali,  Avicenna,  Averroes,  llhases,  and  Damascenus,  all 
of  thera  renowned  Arab  mediciners  and  natural  philos- 
ophers. ,  . 
§  14.  The  French  language,  as  we  have  seen,  soon 
came  to  distinguish  between  the  physician  and  the  pro- 
fessional healer  of  diseases.  From  medicare  came  the 
medieval  Latin  verb,  medicmare,  whence  the  French  verb, 
medeciner,  and  the  substantive,  medeein,  corresponding  to 
which  we  find  in  German  and  in  English  the  substantive, 
medieiner.  Sir  Walter  Scott  puts  into  the  mouth  of  King 
Richard  the  words,  "It  is  unbecoming  a  medieiner  of 
thine  eminence  to  interfere  with  the  practice  of  another,"! 
and  Jamieson  gives  a  Scotch  proverb,  "  Live  in  measure, 
and  laugh  at  the  mediciners."  %  It  is  to  be  wished  that 
this  word  were  generally  adopted  in  our  speech,  since  the 
name  of  physician  is  now  given  to  empirics  who,  whatever 
their  claims  to  be  called  curers,  mediciners,  or  medicas- 
ters, have  no  right  to  be  called  physicians.  The  antago- 
nism between  the  two  schools  is  humorously  shown  in  the 
old  French  quatrain  cited  in  the  note  to  §  10. 


*  Draper,  Intellectual  Development  of  Europe,  I.,  c.  13;  II.,  c.  4. 

t  The  Talisman,  chap,  xviii. 

X  Jamieson's  Scottish  Dictionary  has  Medcinarc,  Medicinar,  and  Medi- 
einer, meaning  the  practitioner  of  medicine,  thus  showing;  a  derivation 
from  the  Latin  verb  medicinare,  the  second  vowel  being  dropped  in  the 
first  form. 


LI 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


11 


II. — PHH^OSOPHICAL. 

§  15.  Having,  in  the  first  part  of  this  essay,  considered 
the  words  physic,  physiology,  and  physician  etymologically 
and  historically,  we  proceed  to  notice  them  in  tiieir  appli- 
cation by  modern  writers.  We  have  already  seen  that 
the  term  physical  science  is  often  restricted  to  those 
phenomena  which  are  common  to  organized  and  unor- 
ganized matter  (§  2).  The  study  of  these  is  now  gen- 
erally designated  in  didactic  language  as  physics,  or  in 
French  physique ;  the  votary  of  such  studies  being  called 
in  English  a  physicist,  and  in  French  a  physicien. 

Physical,  as  an  adjective,  is,  however,  used  in  a  wider 
sense  than  the  above,  when  applied  to  organized  beings. 
It  then  designates  their  organism  and  all  pertaining 
thereto,  as  in  the  expression,  the  physical  life  of  man,  or 
in  the  common  tautological  phrase,  "man's  physical  na- 
ture." 

§  16.  While  the  word  physic,  or  rather  physics,  is  in 
modern  English  generally  limited  to  the  study  of  the  phe- 
nomena of  the  inorganic  world,  the  once  synonymous  term 
physiology  has  come  to  mean,  both  in  English  and  in 
French,  the  study  of  the  organic  functions  of  plants  and 
animals  (and,  by  an  extension  of  the  term,  that  of  the 
functions  of  the  human  mind)  ;  which  are  designated  as 
physiological,  in  contradistinction  to  the  so-called  physical 
phenomena  of  inorganic  nature.  Examples  of  these  limi- 
tations, respectively,  of  the  words  physic  and  physiology, 
and  their  derivatives,  are  familiar  to  every  reader.  Thus, 
William  B.  Carpenter  constantly  distinguishes  between 
physical,  chemical,  and  vital  forces,  the  consideration  of 
the  latter  only,  according  to  him,  belonging  to  physi- 
ology.* 

On  the  other  hand,  we  find  well-known  writers  employ- 
ing the  word  physical  and  its  congeners  indifferently,  in 

*  Relation  of  the  Vital  to  the  Physical  Forces,  Philos.  Transactions, 
1850,  p.  727. 


12 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


tl. 


I'll 


their  wider  and  their  more  restricted  meanings.  Thus,  in 
his  address  before  the  British  Association  for  the  Advance- 
ment of  Science,  at  Belfast,  in  1874,  Tyndall,  in  discussing 
the  activities  of  the  animal,  speaks  successively  of  "  the 
work  of  the  physicist,  .  .  .  the  comparative  anatomist, 
and  the  physiologist."  Following  this,  the  influence  of 
the  nervous  system  "  over  the  whole  organism,  physical 
and  mental,"  is  spoken  of,  and,  a  few  lines  farther  on, 
"  the  physical  life  dealt  with  by  Mr.  Darwin  "  is  distin- 
guished from  "  a  psychical  life  " ;  while,  in  the  next  para- 
graph, we  read  of  "organisms  whose  vital  actions  are 
almost  as  purely  physical  "  as  the  coalescence  of  drops  of 
oil  suspended  in  a  watery  medium  of  the  same  density,  in 
the  classic  experiments  of  Plateau.*  In  the  first  citation, 
the  investigations  by  the  dynamo-physicist  of  the  nervous 
and  muscular  activities  of  the  animal  are  distinguished 
from  those  of  the  biologist.  In  the  second  and  third  cita- 
tions, the  physical  organism  and  the  physical  life  are  dis- 
tinguished, not  as  in  the  preceding,  from  the  chemical  and 
vital  (which  they  evidently  include),  but  from  the  mental 
organization  and  the  psychical  life ;  while  in  the  fourth 
the  antithesis  is  between  physical,  in  the  sense  of  dynami- 
cal, on  the  one  hand,  and  chemical  and  vital  processes  on 
the  other. 

§  17.  Thomson  and  Tait,  in  their  treatise  on  "Natural 
Philosophy,"  wherein  are  considered  only  those  simpler 
phenomena  of  matter  which  are  neither  chemical  nor  vital, 
employ  the  term  Dynamics  for  the  forces  thus  manifested, 
and  divide  the  study  of  them  into  Kinetics  and  Statics^  or 
the  phenomena  of  actual  motion  and  of  rest.  Some  writers 
have  used  static  as  the  antithesis  of  dynamic  (see  farther, 
§  24),  but  statics,  as  implying  simply  equilibrium,  are,  as 
W.  K.  Clifford  has  well  remarked,  "  but  a  particular  case 
of  kinetics,"  and  hence  are  to  be  included  with  the  latter 
under  the  common  title  of  dynamics.     Thomson  and  Tait 

*  Tyndall's  Belfast  Address.    Appleton's  ed.,  pp.  50,  51. 


I.] 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


13 


consider  under  this  head,  besides  the  phenomena  of  ordi- 
nary motion,  the  vibratiuns  wliich  produce  sound,  and 
those  motions  by  which  we  seek  to  explain  the  phenomena 
of  temperature,  radiant  energy,  and  electricity  and  mag- 
netism. The  whole  of  the  phenomena  to  wliich,  in  the 
modern  and  restricted  sense,  the  name  of  Physics  is  gener- 
ally applied,  are  thereby  included  under  the  head  of  Dy- 
namics ;  a  term  which  is  thus  employed  not  only  by  the 
authors  just  cited,  but  by  Clerk  Maxwell,  Ilelmholtz,  and 
Clifford,*  and  will  be  so  used  in  the  following  pages,  while 
the  term  dynamicist  will  replace  ph3'-sicist.  [Berzelius 
had  previously  included  electricity,  magnetism,  light,  and 
heat — all  of  which  he  regarded  as  affections  of  matter, 
and  compared  their  phenomena  with  those  of  sound  — 
under  the  common  name  of  Dynamids,!  thus  anticipating 
the  use  of  the  term  dynamics  as  here  applied.] 

§  18.  Dynamics  in  the  abstract  regard  matter  in  gen- 
eral, without  relation  to  species,  the  genesis  of  which  is 
the  office  of  the  chemical  process,  or  chemism.  This 
gives  rise  to  mineralogical,  or  so-called  chemical,  species, 
which,  theoretically,  may  be  supposed  to  be  formed  from 
a  single  element  or  materia  prima^  by  the  chemical  pro- 
cess. 

"It  is  necessary  to  distinguish  between  the  production 
of  new  species  differing  in  physical  characters  %  and  that 
reproduction  which  belongs  to  organic  existences.  The 
distinction  arises  from  that  individuation  which  marks  the 
results  of  organic  life,  and  is  eminently  characteristic  of 
its  higher  forms.  The  individuality,  not  only  of  the  or- 
ganism, but  of  its  several  parts,  is  more  evident  as  we 
ascend  the  scale  of  organic  life,  while  inorganic  bodies 
have  a  specific  existence,  but  no  individuality;  division 

*  W.  K.  Clifford,  Essays,  II.,  17.  This  author,  following  the  French 
usage,  employed  the  substantive  Dynamic  in  a  treatise  on  the  subject, 
thus  entitled ;  but  the  plural  form.  Dynamics,  is  preferable,  as  serving  to 
distinguish  it  from  dynamic  used  adjectively. 

t  Berzelius,  Traite  de Chimie.    Second  edition.  Paris:  1885.  pp.  14,35. 

t  That  is  to  say,  differing  in  dynamic  relations. 


ill 


14 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


i|L 


does  not  destroy  them.  Crystallization  is  a  commenco- 
ment  of  individuation. 

"  That  mode  of  generation  which  produces  individuals 
like  the  parent,  can  present  no  analogy  to  the  phenomena 
under  consideration  ;  metagep^ois,  or  alternate  generation, 
and  metamorphosis  are,  however,  to  a  certain  extent,  pre- 
figured in  the  chemical  changes  of  bodies.  Their  meta- 
genesis is  effected  in  two  ways :  by  condensation  and 
union,  on  the  one  hand,  and  by  expansion  and  division  on 
the  other.  In  the  first  case,  two  or  more  bodies  vuute  and 
merge  their  si)ecifio  characters  in  those  of  a  new  species. 
In  the  second  case,  this  process  is  reversed,  and  a  body 
breaks  up  into  two  or  more  new  species,  Metamorphosis 
is,  in  like  manner,  of  two  kinds:  in  metamorphosis  by 
condensation  only  one  species  is  concerned,  and  in  meta- 
morphosis by  expansion  the  result  is  homogeneous  and 
without  specific  difference.  The  chemical  history  of 
bodies  is  a  record  of  these  changes ;  it  is,  in  fact,  their 
genealogy. 

"  The  processes  of  union  and  division  embrace  by  far 
the  greater  number  of  chemical  changes,  in  which  meta- 
morphosis sustains  a  less  important  part.  By  union,  we 
rise  to  indefinitely  higher  species;  out  in  division,  a  limit 
is  met  with  in  the  production  of  species  which  seem  inca- 
pable of  further  division,  and  these,  being  regarded  as  pri- 
mary or  original  species,  are  called  chemical  elements. 
These  two  processes  continually  alternate  with  each  other, 
and  a  species  produced  by  the  first  may  yield,  by  division, 
species  unlike  its  parents.  From  this  succession  results 
double  decomposition  or  equivalent  substitution,  which 
always  involves  a  union  followed  by  division,  although, 
under  the  ordinary  conditions,  the  process  cannot  be 
arrested  at  the  intermediate  stage." 

§  19.  I  have  quoted  the  three  preceding  paragraphs 
from  an  essay  published  by  myself  in  1853,  on  "The 
Theory  of  Chemical  Chanjj^es."  Therein  I  also  Avrote, 
"  Chemical  combination  is  interpenetration,  as  Kant  has 


' '!  ! 


I      :"[! 


I.] 


NATUKE  IN  THOUGHT  AND  LANGUAGE. 


16 


taught.  When  bodies  unite,  their  bulks,  like  their  speeific 
chunicters,  are  lust  in  that  of  the  new  s[>eeies."  In  1854, 
in  an  essay  entitled  "Thoughts  on  Solution,"*  I,  however, 
declared,  with  regard  to  Kant's  view,  that  "  the  conception 
is  mechanical,  and  therefore  fails  to  give  an  adequate 
idea.  The  definition  of  Hegel,  that  the  chemical  process 
is  an  identifieation  of  the  ditt'erent,  and  a  differentiation 
of  the  identical,  is,  however,  completely  adequate.  Chem- 
ical union  involves  an  identification  not  only  of  the  vol- 
umes (interpenetration,  mechanically  considered),  but  of 
the  specific  characters  of  the  combining  bodies,  which  are 
lost  in  those  of  the  new  species.  .  .  .  We  may  say  that 
all  chemical  union  is  nothing  else  than  solution  ;  the  unit- 
ing species  are,  as  it  were,  dissolved  in  each  other,  for 
solution  is  mutual." 

The  above  considerations  will  serve  to  show  the  essen- 
tial nature  of  chemism,  a  process  resulting  in  the  genesis 
of  chemical  species,  which  are  mineral  or  inorganic. 

§  20.  The  force  involved  in  the  chemical  process  mani- 
fests itself  as  radiant  energy  and  electricity,  and  there 
is  apparently  a  tendency  among  modern  dynamicists  to 
confound  these  activities  with  chemism  itself,  and  thus  to 
lose  sight  of  the  essential  significance  of  the  chemical  pro- 
cess as  already  defined.  Thus  Clifford  wrote  of  molecular 
motion  "which  makes  itself  known  as  light,  or  radiant 
heat,  or  chemical  action,"!  while  Faraday  was  wont  "to 
express  his  conviction  that  the  forces  termed  chemical 
affinity  and  electricity  are  one  and  the  same."  Helmlioltz, 
from  whom  I  here  quote,  adds,  "  I  think  the  facts  leave  no 


*  Of  the  two  essays  above  quoted,  the  first  appeared  in  18.53,  in  the 
American  Jonrnal  of  Science  for  March,  and  also  in  the  L.,  E.  and  D.  Phi- 
los.  Magazine  [4]  v.,  trlQ,  and  was  translated  into  German  in  the  Chemis- 
ches  Centralblatt  for  1853,  page  849.  The  second  was  published  in  the 
American  Journal  of  Science  for  January,  1854,  and  also  in  the  Chemical 
Gazette  for  1855,  page  90.  Both  will  be  found  in  the  author's  volume  of 
"Chemical  and  Geological  Essays,"  in  which,  for  the  extracts  here  given, 
Bee  pages  427,  428,  and  450. 

t  W.  K.  Clifford,  Essays  II.,  17. 


16 


NATUKU   IN   THOUOIIT   AND   LANGUAGE. 


[I. 


•I'll! 

tiiii'" 


4. 


doubt  that  the  very  mightiest  among  the  chemical  forces 
are  of  electrical  origin,  .  .  .  but  I  do  not  Huppose  that 
other  molecular  forces  are  excluded,  working  directly  from 
atom  to  atom."  * 

The  activities  which  appear  in  dynamic  and  in  chemio 
phenomena  are  one  in  essence,  for  force  is  one.  The  same 
is  true  of  the  activities  manifested  in  organic  growth,  and 
even  in  thought;  but  the  unity  and  mutual  convertibility 
of  different  manifestations  of  force  afford  no  ground  for 
confounding,  as  some  would  do,  dynamics  with  chemics, 
or  with  vital  or  mental  processes.  All  of  tiieso  phenomena 
are  but  the  evidences  of  universal  animation,  or,  in  other 
words,  of  an  energy  which  is  inherent  in  matter,  the  mani- 
festations of  which,  as  matter  rises  to  higher  stages  of 
development,  become  more  complex,  as  organic  individ- 
uals are  themselves  more  complex  than  mineral  forms,  f 

§  21.  From  the  process  which  generates  chemical  species 
we  pass  to  that  which  gives  rise  to  organized  individuals, 

*  Helmholtz,  The  Faraday  Lecture,  April  5,  1881;  abstract  prepared 
by  its  autlior;  Nature,  vol.  xx'U.,  p.  539. 

t  [This  view  of  hylozoisiu  v  .s  well  set  forth  l)y  rosinini.  According 
to  him,  in  the  words  of  his  intPit-rtacr,  Davidson,  "  tlic  ultimate  particles 
of  matter  are  animate,  each  atom  having  united  with  it,  and  forming  its 
unity  or  atomicity,  a  sensitive  principle.  Wlien  atoms  chemically  com- 
bine, their  sensitive  principles  become  one.  '.  .  .  The  unit  of  natural 
existence  is  neither  force  nor  matter,  but  sentience,  and  through  this  all 
the  material  and  dynamical  phenomena  of  nature  may  be  explained." 
From  the  unifications  of  these  sensitive  principles,  or  elementary  souls, 
which  take  place  in  the  combinations  of  matter,  higher  and  higher  mani- 
festations of  sentience  appear,  constituting  the  various  activities  dis- 
played in  crystals,  in  plants,  and  in  animals.  From  these  elementary 
souls  organic  souls  are  built  up,  and  "when  these  are  resolved  into  the 
elementary  ones  through  the  dissolution  of  the  organized  bodies,  the 
existence  of  the  souls  does  not  cease,  but  is  merely  transformed."  [See 
"The  Philosophical  System  of  Kosmini."  by  Thomas  Davidson  (18S2), 
pp.  284-301.)  This  volume  was  unpublished,  and  these  views  of  Rosmini 
were  unknown  to  me,  at  the  time  of  writing  the  above  pages.  The  em- 
inent biophysiologist,  the  late  William  B.  Carpenter,  in  an  essay  on 
"  Life,"  published  in  1847,  in  Todd's  "  Cyclopedia  of  Anatomy  and  Physi- 
ology," Vol.  III.,  p.  151,  contends  that  organization  and  biotical  func- 
tions arise  from  the  natural  operation  of  forces  inherent  in  elementary 
matter.] 


I.l 


NATURE  I^  THOUGHT  ANU  LANOUAUE. 


17 


ill  wlrch  appear  a  new  class  of  pluMioinena,  distiiiguisliod 
alike  'nun  those  of  dynainics  and  llioso  of  clieiiiisin.  These 
new  manifestations,  wliich  are  cuIUmI  vital,  involve  dynam- 
ical and  chemical  activities,  hnt  disi)hiy,  in  addition  to 
these,  still  higher  ones.  Matter,  on  this  more  elevated 
plane,  not  only  bueomes  individnalized,  but  adajjts  itself  to 
external  conditions,  by  orgaid/ation,  and  exhibits  in  the 
resulting  forms  the  power  of  growth  by  assimilation,  and  of 
reproduction.  The  study  of  these  forms  in  all  their  rela- 
tions is  the  object  of  Hiology.  Organogeny,  or  the;  process 
of  morphological  growth  and  (levelo[)ment,  distinguishes 
the  biological  from  the  nuneralogical  individual.  The  ac- 
tivities of  the  crystal  are  purely  dynamic,  and  its  crystal- 
line individuality  must  be  destroyed  before  it  can  become 
the  subject  even  of  chendsm,  while  the  plant  and  the  aiumal 
exhibit  not  oidy  dynamical  and  chemical,  but  organogenic 
activities,  which  last  are  designated  as  vital  phenomena. 
Tiio  study  of  these  constitutes  a  third  division  of  physics, 
which  may  be  conveniently  designated  as  lliotics  (fro;n 
^toTix6i^  pertaining  to  life),  and  has  to  do  with  organic 
growth,  development,  and  reproduction,  activities  which 
do  not  api)ear  in  the  mineral  kingdom. 

Mineralogy  is  the  science  of  inorganic  matter,  and 
studies  its  dynamical  'and  chemical  relations,  while  Biol- 
ogy, which  is  the  science  of  organic  matter,  adds  to  these 
the  study  of  biotic  relations.  The  dynamic  and  ehemic 
activities  which  in  the  mineral  kingdom  give  rise  to  the 
crystalline  individual,  are  therein  in  static  equilibrium. 
The  organic  individual,  on  the  contrary,  is  j'.inetic,  and 
maintains  its  equilibrium  only  by  perpetual  adjustment 
with  the  outer  world. 

§  22.  General  physic,  or  the  study  of  nature,  presents 
itself  under  a  twofold  aspect,  the  historical  and  the  philo- 
sophical ;  the  former  gives  rise  to  physiography,  while  to 
the  latter  the  name  of  physiology  more  i)roperly  belongs. 
Physiography  describes  si)0oif.<3  and  individual  forms,  and 
their  external  relations,  while  physiology  investigates  the 


18 


NATUEE  IN  THOUGHT  AND  LANGUAGE. 


CI* 


r 


II 


'II    I 


processes  by  which  these  forms  are  produced,  and  gives 
us  the  logic  of  nature.  The  physiology  of  matter  in  the 
abstract  is  dynamic,  that  of  mineral  forms  is  both  dynamic 
and  chemic,  while  that  of  organic  forms  is  at  once  dynamic, 
cheraic,  and  biotic. 

Nature  in  all  its  manifestations  constitutes  a  unity,  and 
it  is  the  object  of  general  phsyiology  to  study  the  process 
of  ceation  in  the  material  world  from  primal  matter  up- 
ward through  its  various  forms  until  it  attains  to  organi- 
zation, and  at  length,  in  man,  to  self-consciousness,  where 
the  domain  of  physiology  ends  and  that  of  psychology 
begins. 

§  23.  In  accordance  with  th'e  views  here  enunciated,  all 
matter  is  in  a  sense  living,  "all  movement  is  radically 
vital,"  *  though  we,  in  common  language,  refuse  the  desig- 
nation of  vital  to  those  lower  forms  of  material  activity 
which  appear  in  dynamic  and  chemic  phenomena,  reserving 
it  for  such  as  are  supposed  to  be  peculiar  to  organized 
forms,  which,  to  prevent  misconception,  I  have  called 
biotic.  When  matter,  through  chemism,  attains  the  con- 
dition of  protoplasm,  which  may  be  chemically  described 
as  a  colloidal  albuminoid  united  with  more  or  less  water, 
it  begins  to  exhibit  that  form  of  activity  which  we  term 
vital,  or  biotic.  "  The  mobility  and 'the  spontaneous  move- 
ments of  this  substance,"  says  Allman,f  "result  from  its 
proper  irritability.  From  the  facts  there  is  but  one  legiti- 
mate conclusion,  that  life  is  a  property  of  protoplasm."  J 

§  24.   Many  of  the  peculiar  characters  of  protoplasmic 

*  Stallo,  Philosophy  of  Nature,  p.  66. 

t  Alhnan,  Presidential  Address  before  the  British  Association  for  the 
Advancement  of  Science,  in  1879. 

t  The  views  set  forth  in  this  and  the  three  sections  preceding  may  be 
compared  with  those  concisely  expressed  by  Huxley  since  the  preceding 
pages  were  first  printed,  in  his  address  in  August,  1881,  before  the  Inter- 
national Medical  Congress  in  London.  He  thereir'  concludes  that  the 
"contrast  between  living  and  inert  matter,  on  which  Bicliat  lays  such 
stress,  does  not  exist.  .  .  .  Living  matter  differs  from  other  matter  in 
degree,  and  not  in  Itind ;  the  microcosm  repeats  the  macrocosm,  and  one 
chain  of  causation  connects  the  nebulous  original  of  suns  and  planetary 


W  ! 


n 


NATUEE  IN  THOUGHT  AND  LANGUAGE. 


19 


matter  appear  to  be  common  to  chemical  species  in  the 
colloidal  condition.  The  remarkable  properties  exhibited 
by  colloids  led  their  discoverer,  Graham,  twenty  years 
since,  to  declare,  "  The  colloidal  is,  in  fact,  a  dynamical 
[kinetic]  state  of  matter,  the  crystalloidal  being  the  stati- 
cal condition.  The  colloid  possesses  Energla ;  it  may  be 
looked  upon  as  the  probable  primary  source  of  the  force 
appearing  in  the  phenomena  of  vitality.  To  the  gradual 
manner  in  which  colloidal  changes  take"  place  (for  tliey 
always  require  time  as  an  element)  may  the  characteristic 
protraction  of  chemico-organic  changes  also  be  referred."  * 

Following  Graham,  Herbert  Spencer  has  noted  that  plia- 
bility, elasticity,  the  power  of  absorbing  water  with  change 
of  bulk,  and  the  phenomenon  of  osmosis,  —  the  whole  of 
which  are  well  designated  by  him  as  showing  sensitiveness 
to  external  agencies  which  are  mechanical  or  quasi-me- 
chanical—  are  possessed  in  common  by  mineral  colloids 
and  by  organized  substances.  These  phenomena  are  exam- 
ples of  that  "  continuous  adjustment  of  internal  relations 
to  external  relations "  which  characterizes  organic  life.f 
"When  the  chemist  shall  have  succeeded  by  his  synthesis  in 
producing  a  colloidal  albuminoid  having  the  same  chemi- 
cal constitution  as  protoplasm,  there  is,  as  Barker  has  well 
said,  reason  to  expect  that  it  will  exhibit  all  the  phenomena 
of  life  which  appear  in  the  protoplasmic  matter  common 
to  plants  and  animals. 

§  25.  Barker  has,  in  this  connection,  asked  the  impor- 
tant question :  What  are  we  to  understand  by  organic  life, 
and  what  is  the  true  meaning  of  vital,  as  applied  to  a 
function?!     If,  with  him,  we  answer,  following  Kiiss, — 


systems  with  the  protoplasmic  foundation  of  life  and  organizations." 
(Nature,  Aug.  11,  1881,  vol.  xxiv.,  p.  34G. ; 

*  Thomas  Graham.  Chemical  and  Physical  Researches,  p.  554,  from 
Philosophical  Transactions  for  ISOl,  p.  183. 

t  Herbert  Spencer,  Principles  of  Biology,  vol.  i.,  part  1,  chapters  1  and  2. 

t  Geo.  P.  Barker,  Address  as  President  of  the  American  Association 
for  the  Advancement  of  Science,  Boston,  August,  1880.  I  have  in  this 
paragraph  closely  followed  Professor  Barker's  argiunent. 


20 


NATUKE  IN  THOUGHT  AND  LANGUAGE. 


[L 


I 

•  i; 

iil 

! 
i  • 

"life  is  all  that  cannot  be  explained  by  dynamics  and  che»^^- 
ism,"  we  shall  find,  restricting  our  inquiries  to  the  animal 
economy,  that  a  large  part  of  the  phenomGua  commonly 
called  vital,  —  and  as  such  included  under  the  head  of  ani- 
mal physiology,  —  are  dynamic  or  chemic.  Tlie  law  of  the 
conservation  of  energy  applies  as  rigidly  to  a  living  animal 
as  to  a  thermic  engine,  and  the  amount  of  work  done,  or  of 
heat  evolved,  is  measured  by  food  consumed  in  the  former 
as  it  is  by  the  fuel  burned  in  the  latter ;  the  energy  mani- 
fested in  both  cases  being  dependent  on  the  oxydation  of 
carbon  and  hydrogen.  Recent  inquiries  go  far  to  confirm 
the  view  that  muscular  contraction  is  electrical,  and  that 
electrical  manifestation  in  the  muscles  is,  as  in  our  ordinary 
batteries,  dependent  on  chemism.  The  tendency  of  late 
investigations  is  to  bring  nervous  activity  into  the  same 
category,  and  the  electrical  nature  of  capillarity  has  been 
shown  by  Draper  and  by  Lippmann.  The  animal  circula- 
tion is  a  mechanical  result  of  muscular  contraction ;  the 
aeration  and  the  coagulation  of  the  blood,  and  the  process 
of  digestion,  are  chemical,  while  absorption  finds  an  expla- 
nation in  the  phenomena  of  diffusion  and  osmosis. 

When  the  energy  which  is  in  matter  is  manifested 
without  reference  to  species,  we  call  it  simply  dynamics ; 
when  it  results  in  the  production  of  mineral  species,  we 
call  it  chemics,  or  chemism ;  and  when  it  gives  rise  to 
organisms,  which  may  be  defined  as  kinetic  individuals, 
we  distinguish  it  as  vital,  or  biotic.  In  matter,  we  must 
recognize  with  Tyndall  "  the  promise  and  the  potency  of 
all  terrestrial  life."  * 

*  [Address  as  President  of  the  British  Association,  Belfast,  1874.  Ap- 
pleton's  ed.,  p.  59.  In  another  version  of  this  address,  cited  by  Stallo, 
Tyndall  declares  that  he  discerns  in  matter  "  the  promise  and  the  potency 
of  every  form  and  quality  of  life,"  respecting  which  Stallo  remarks: 
"  Tyndall's  words  were  little  more  tlian  a  new  wording  of  an  old  thouglit 
of  Francis  Bacon,  who  said,  more  than  two  centuries  ago:  '  And  matter, 
whatever  it  is,  must  be  held  to  be  so  adorned,  furnislied,  and  formed,  that 
all  virtue,  essence,  action,  and  natural  motion  may  be  the  natural  conse- 
quence and  emanation  tliereof '  ('Atque  asserenda  materia,  qualiscunque 
ea  sit,  ita  ornata  et  apparata  et  formata  ut  omnis  virtus,  essentia,  actus 


h] 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


21 


§  26.  It  follows,  from  what  has  been  said,  that  the 
word  physiology,  as  popularly  limited  to  the  fimctioRS  of 
living  beings,  is  made  to  include  many  phenomena  which 
are  not  biotic,  but  are  common  ^o  the  organic  and  mineral 
kingdoms,  and  that  we  need  some  further  definition  to 
distinguish  those  which  are  characteristic  of  organic  life. 
I  therefore  venture  to  designate  the  study  of  these 
by  the  distinctive  name  of  Biophysiology,  while  those 
phenomena  which  are  recognized  as  simply  dynamic,  or 
dynamic  and  chemic,  whetlier  manifested  in  organisms  or 
in  mineral  species,  may  be  included  under  the  name  of 
Abiophysiology. 

General  physiology,  comprehending  these  two  divisions, 
will  thus  be  restored  to  its  original  and  proper  significa- 
tion, as  an  inquiry  into  the  reason  of  all  things  in  the 
material  universe,  and  as  distinguished  from  physiography, 
whose  province  is  the  description  of  universal  nature. 
Scientific  precision  demands  a  reform  in  our  terminology, 
and  requires  us  to  extend  the  name  of  physiology  once 
more  to  the  processes  and  the  activities  of  the  three  king- 
doms of  nature.  The  inorganic,  not  less  than  the  organic 
world,  has  its  physiology.  On  the  other  hand,  the  study 
of  mind  and  spirit,  and  the  phenomena  of  consciousness, 
which  Locke  and  Thomas  Brown  included  under  the  head 
of  physic  and  physiology,  should  be  relegated  to  the 
domain  of  psychology. 

§  27.  The  kindred  term  physiography  is  now  correctly 
employed  in  a  general  sense,  wil-h  a  meaning  co-extensive 

atqwe  motiis  naturalis  ejus  consecutio  et  emanatio  esse  posslt.'  Baco,  De 
Princ.  atqiie  Orlgg.,  0pp.  ed.  Bohn,  vol.  ii.,  p.  GDI).  The  same  thing  has 
been  repeated  many  times  since  by  the  metaphysical  evolutionists,  in 
terms  substantially  like  those  of  Schelllng:  '  Matter  is  the  general  seed- 
corn  of  the  universe  wherein  everything  is  involved  that  Is  brought  forth 
in  subsequent  evolution '  ( '  Die  Materie  ist  das  allgemeine  Samenkorn  des 
Universuras,  warin  Alles  verhiillt  ist  was  in  spiiteren  Entwickelungen 
sich  entfaltet.'  Schelling,  Ideen  zu  einer  Philos.  der  Natur,  2d  ed., 
p.  315)  "  Stallo,  The  Concepts  and  Theories  of  Modern  Physics,  pp.  153, 
154.  Compare  with  this  the  view  of  W.  B.  Cai-penter  cited  in  a  note  to 
§  20,  supra,  page  16.] 


KAXCBK  ™  THOUGHT   A^r>  ^ASGUAGE. 


II. 


•I     -^^  .n-v     A  great  living 

^Hh  that  wMch  --'tv  Ms'^v'^  "^ -'^-  *''^  *'''^  "^^ 
teaoHer,  Professor  H»rie5^;  has  g we         ^         ^^  ;, 

«  Physiography  ;  an  In'-^f  "»j"'"  ,  °  ,  describing  the  rocKs, 
„  elementary  '^^''''^^V^''^;;!";  .Aich  make  up  the  in- 
the  waters,  and  the  ''f"^?^^!^' J\,,„eeeds  to  cons  der 
organic  portions  f  ^^''"tnimaU  and  their  relaUons 
the  development  o  P  ™*;^^°^,^i  kingdom,  and  cone  udcs 
::rrrnforthrar— irelationsofourplanet 

^-:::lrs;iro^«.— -^-4p 

without  which  a  trne  -p^'^^^ZTs,"  a  complete  physi- 
Humboldt  to  attempt,  ..    h^J  ^i,,eription  of  the 

ography,  which  -''''"''^^^^^'J  things  in  the  regions  of 
universe,  em.bracmg  all  "^^^^^j^t  ^elsewhere  speaks  of 
space  and  in  the  earth.       ^mnb  associated  w.th 

/the  idea  of  vitality  •  •  •/"  '"  ever-blending  natural 
that  of  the  OKistenee  »f«-J  Sphere,"  and, recallmg 
forces  which  animate  t^e  terrest'        P  .^^^^^^^^  „ 

the  fact  that  the  inorganic  crust  of  t         ^^^^  ^^  ^^ 

same  chemical  elements  that  «»';         „  ^^  physical  cos- 
Til  and  vegetaWe  ;r,a„.m  ^a^a^^^^^^  |  ,,  to 

mography  *o»"l^.'^^''ftLse  {orce3,-and  of  the  sub- 
omit  a  C''"»i'l^™*'"^  °*  *ud  and  liquid  combinations  in 
stances  that  enter  into  ^^^^^''^^J^^,,,^  _  which,  from 

organic  tissues  un^    "^^^n  t---  ^  "^'T'"     \  t. 
our  ignorance  of  their  actu  j„,ai  tendency  of  the 

vague  term  of  vital  forces.    The  n  ^^^^  ^^y^^. 

Lman  mind  '"-f  ™*S^Zgh  all  their  varied  series, 
cal  phenomena  of  the  e'''*  *^f  ^ ^  morphological  evolu- 
r  orvei:t";rmt  25  =elf.etermining  powersof 


I.] 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


23 


ophy  of  the  material  universe,  or,  in  other  words,  a  gen- 
eral physiology.  The  most  complete  attempt  at  thus 
systematizing  nature  is  that  of  Lorenz  Oken,  who  divided 
all  philosophy  into  Pneumatophilosophy  and  Physiophilos- 
ophy,  corresponding  respectively  to  Spirit  and  to  Nature. 
Physlophilooophy,  as  defined  by  him,  is  the  scie'ice  of 
the  conversion  of  Spirit  into  Nature,  and  has  for  its 
object  to  show  how,  and  in  accordance  »vith  what  laws, 
tlie  material  universe  has  been  formed;  to  portray  the 
first  periods  of  the  world's  development  from  naught; 
to  show  how  the  heavenly  bodies  and  the  chemical  ele- 
ments originated ;  in  what  manner,  Ijy  self-evolution  into 
higher  and  manifold  forms,  these  generated  mineral  spe- 
cies became  at  length  organic,  and  in  man  attained  to 
self-consciousness. 

Physiophilosophy  is  therefore  the  generative  history  of 
the  world,  or,  in  other  words,  the  history  of  the  process 
of  creation.  It  aims,  in  the  language  of  Stallo,  to  describe 
"  the  genetic  evolution  of  the  material  world ;  therefore, 
also,  its  first  origin  in  naught,  and  its  subsequent  develop- 
ment up  to  its  limit,  man,  who  is  a  complex  of  all  j^reced- 
ing  forms,  includes  all  particular  developments,  and  is,  as 
it  were,  the  focus  where  all  the  various  tendencies  of 
Nature  converge.  ...  In  man,  all  eternal  activities,  all 
divine  ideas  are  gathered " ;  and  thus  it  is  that,  in  the 
words  of  the  poet,  he  is  enabled  "  to  think  again  the  great 
thought  of  the  creation  "  * 

§  29.  The  origin  of  matter  itself,  Hylogeny,  belongs  to 
Pneumatophilosophy.  The  genetic  process  in  the  primal 
undifferentiated  matter,  with  wliieh  Physiophilosophy 
first  concerns  itself,  is  by  Oken  considered  under  the  two 

*"  Schcin  ist,  Mutter  Natur,  deiner  Erfindung  Praeht 
Auf  die  Fluren  verstreut ;  schoner  ein  froh  Gesicht 
Das  den  grossen  Gedanken 
Deiner  Schopf  ung  nocli  einmal  denkt." 

Klopstock,  Ode,  Dcr  Zii.rcJicrsee. 
Compare  this  with  the  language  of  SchelHng,  cited  by  Ilegel :  "  Uber 
die  Natur  philosophiren  heisst  die  Natur  schaffen." 


24 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


n. 


m 


ill! 


HI!    !  ' 

11 


heads  of  Ontology  und  Biology.  The  successive  steps  in 
the  ontological  process  are,  first,  Cosmogony,  or  the  fash- 
ioning of  the  heavenly  bodies  from  the  previously  formed 
matter ;  followed  by  the  genesis  therefrom  of  the  chemical 
elements ;  Stoichiogeny.  These  elements  give  rise  to 
mineral  species,  which  together  make  up  the  earth ;  Geo- 
geny.  Biology,  wJiich  has  for  its  object  the  study  of  the 
organic  world,  is  by  Oken  div'ded  into  Organogeny,  with 
its  sub-divisions,  and  Phytosophy  and  Zoosophy,  treating 
respectively  of  the  development  of  plants  and  animals. 
In  the  organism  we  have  "  a  combination  of  all  the  activi- 
ties of  the  universe  in  a  single  individual  body."  The 
inorganic  and  the  organic  worlds  are  not  only  in  harmony 
with  each  other,  but  are  one  in  kind.  Man,  in  whom 
self-consciousness  or  Spirit  manifests  itself,  represents  the 
whole  universe  in  miniature.* 

§  30.  The  physiophilosophy  of  Oken,  of  which  we  have 
given  an  outline,  is  thus  identical  in  its  aim  and  its  plan 
with  the  earlier  attempts  of  the  Greek  philosophers  to 
which  the  name  of  physiology  was  given,  and  the  two 
terms  are,  in  fact,  synonymous.  The  study  of  nature,  as 
has  been  shown,  divides  itself  into  physiography  and  phy- 
siology, and  this  division  applies  equally  to  each  one  of 
the  three  great  kingdon.s  of  nature.  Thus,  for  example, 
Physiographical  Botany  studies  the  relations  of  plants  to 
each  other  as  members"  of  the  vegetable  kingdom,  and 
investigates  the^r  external  forms  and  relationships,  by 
which  we  arrive  at  Systematic  and  Descriptive  Botany, 
with  its  classification  and  terminology.     These  together 

*  Lorenz  Oken,  Physiophilosophy  ;  Introduction,  pp.  1-3,  of  Tulk's 
translation,  published  by  tlie  Ray  Society,  London,  1847.  See  also  an 
excellent  analysis  of  the  system  by  J,  B.  Stallo  in  his  Philosophy  of 
Nature,  Boston,  184S,  pp.  221-330,  from  which  we  have  quoted  above. 
Errors  in  detail,  and  defects,  and  obscurities,  are  to  be  foimd  in  the 
system  of  Oken,  which  even  novices  in  science  can  to-<lay  point  out  and 
criticise  ;  but  it  must  not  be  forgotten  that  his  physiophilosophy  has  been 
a  most  potent  influence  in  shaping  and  directing  the  scientitlc  thought  of 
the  last  two  generations.  Oken  has  been  the  inspirer  and  the  teacher  of 
the  teachers  of  science. 


I] 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


25 


give  us  Botany  as  a  great  division  of  Natural  History. 
Physiological  Botany,  on  the  other  hand,  considers  che 
individual  plant  in  itself,  as  seen  in  its  structure,  growth, 
and  development,  and  in  its  relations  to  the  otlier  king- 
doms of  nature.  It  is  properly  divided  into  Structural 
Botany,  which  investigates  the  anatomy,  organography, 
and  morphology  of  tlu  plant,  and  Vegetable  Physiology, 
whioli  studies  the  functions  of  the  vegetable  organism,  its 
growth,  nutrition,  and  decay,  and  the  interdependence  of 
the  vegetable,  animal,  and  mineral  kingdoms.*  The  same 
distinctions  and  definitions  will  apply,  mutatis  mutandis^ 
to  Physiographical  and  Physiological  Zoology. 

§  31.  The  vastness  and  the  complexity  of  the  inorganic 
as  compared  with  the  organic  world  of  nature,  make  it 
difficult  to  grasp  at  once  a  conception  of  tlie  true  relations 
of  Mineralogy,  which  comprehends  the  study  of  all  forms 
of  unorganized  matter. f  Phj'siographical  Mineralogy,  in 
its  widest  sense,  has  thus  for  its  object  not  only  this  earth, 
but  all  other  matter  in  space,  and  includes,  so  far  as  our 
planet  is  concerned.  Geognosy  and  Petrography,  besides 
Systematic  and  Descriptive  Mineralogy  as  generally 
understood. 

In  the  study  of  mineralogy  in  its  physiological  aspect,  we 
have  to  consider  the  various  conditions  of  mineral  matter, 
distinguished  as  gaseous,  liquid,  or  solid,  as  amorphous, 
crystallized  in  different  geometric  forms,  or  colloidal. 
These  unlike  conditions  of  matter,  and  their  different 
relations  to  gravity,  pressure,  temperature,  sound,  ra  liant 
energy,  ele  .ricity,  and  magnetism,  the  phenomena  of 
capilla4ty,  and  of  the  occlusion,  diffusion,  and  transpira- 
tion of  gases  and  liquids,  indicate  structural,  or,  as  we 
sometimes  term  them,  n.olecular  differences  in  mineral 
species,  which  mak'^  up  what  we  must  include  under  the 
iitle  of  Structural  Mineralogy. 

*  Asa  Gray,  Structural  and  Systematic  Botany  ;  Introduction, 
t  See  the  author  on  the  Objects  and  Methods  of  Miceralogy  ;  Chemical 
and  Geological  Essays,  p.  453. 


26 


NATURE  IN  THOUGHT  AND  LANGUAGE. 


[I. 


§  32.  The  changes  of  mineral  species  from  one  condition 
to  another,  and  tlieir  transformations  under  the  influences 
of  the  agencies  already  noticed,  including  the  phenomena 
of  chemism,  which  give  rise  to  new  species,  make  up  to- 
gether the  dynamic  and  chemic  activities  of  matter,  which 
constitute  the  secular  life  of  the  planet.  They  are  the 
geogenic  agencies  which,  in  the  course  of  ages,  have 
moulded  the  mineral  mass  of  the  earth,  and  from  primeval 
chaos  have  evolved  its  present  order,  formed  its  various 
rocks,  filled  the  veins  in  its  crust  with  metals,  ores,  gems, 
and  spars,  and  determined  the  composition  of  its  waters 
and  its  atmosphere.  They  still  regulate  alike  the  terres- 
trial, the  oceanic,  and  the  aerial  circulation,  and  preside 
over  the  constant  change  and  decay  by  which  the  face  of 
the  earth  is  incessantly  renewed,  and  the  conditions  neces- 
sary to  organic  life  are  maintained.  To  the  study  of  these 
processes  we  may,  with  propriety,  apply  the  name  of  Min- 
eral Physiology.* 

*  I  have  elsewhere  made  use  of  this  term  in  speaking  of  the  phenomena 
connected  with  the  decay  and  transformations  of  silieated  roclss,  as  be- 
longing to  "  the  domain  of  wliat  I  venture  to  call  mineral  physiology." 
Canadian  Naturalist,  1880,  new  series,  vol.  ix.,  page  435. 

As  a  comment  upon  the  views  expressed  on  pages  16-18,  we  here  cite 
from  an  address  by  the  writer  on  "  The  Relations  of  the  Natural  Sci- 
ences," Trans.  Roy.  Soc.  Can.,  I.,  sec.  iii.,  p.  4:  "When  we  have 
attained  to  the  conception  of  hylozoism,  —  of  a  living  material  universe, 
— the  mystery  of  Nature  is  solved.  The  Cosmos  is  not,  as  some  would 
have  it,  a  vast  machine  wound  up  and  set  in  motion  with  the  certainty 
that  it  will  run  down,  like  a  clock,  and  arrive  at  a  period  of  stagnation 
and  death.  The  modern  theory  of  thermodynamics,  though  true  within 
its  limitations,  has  not  grasped  the  problem  of  the  imiverse.  The  force 
that  originated  and  impelled,  sustains,  and  is  the  L>ivine  Spirit,  which 

'"  Lives  through  all  life,  extends  through  all  extent. 
Spreads  undivided,  operates  unspent.'  " 

"  The  law  of  birth,  growth  and  decay,  of  endless  change  and  perpetual 
renewal,  is  everywhere  seeA  working  throughout  the  Cosmos  —  in  nebula, 
in  world,  and  in  sun,  as  in  rock,  in  herb,  and  in  man,  all  of  which  are 
but  passing  phases  in  the  endless  circulation  of  the  universe,  —  in  that 
perpetual  new  birth  which  we  call  Nature.  This,  it  will  be  said,  is  the 
poet's  view,  but  it  is  at  the  same  time  the  one  which  seems  forced  upon 
us  as  the  highest  generalization  of  modern  science." 


n. 


THE  ORDER  OF  THE  NATURAL  SCIENCES. 

The  system  of  classlflcation  set  forth  in  the  preceding  essay  on  Nature  in 
Thought  and  Language  was  embodied  in  tlio  following  note  presented  to  the  Ameri< 
can  Association  for  the  Advancement  of  Science,  at  Minneapolis,  August,  1883. 
This  was  published  at  the  time  in  Science,  in  the  Proceedings  of  the  Association,  and 
also  the  same  year  as  an  appendix  to  an  address,  by  the  author,  on  The  Relation  of 
the  Natural  Sciences,  in  the  Transactions  of  the  Royal  Society  nf  Canada. 
Volume  I.,  section  iii.,  pages  7-8. 

§  1.  The  study  of  material  nature  constitutes  wiiat  the 
older  scholars  correctly  and  compreliensively  termed 
physics  (the  words  physical  and  natural  being  synony- 
mous), and  presents  itself  in  a  twofold  aspect,  first  as 
descriptive,  and  second  as  philosophical,  —  a  distinction 
embodied  in  the  terms  Natural  History  and  Natural 
Philosophy,  or  more  concisely,  in  the  words  Phj^siography 
and  Physiology.  The  latter  word  has,  from  the  time  of 
Aristotle,  been  employed  in  this  general  sense  to  desig- 
nate the  philosophical  study  of  nature,  and  will  so  be 
used  in  the  present  classification. 

§  2.  The  world  of  nature  is  divided  into  the  inorganic 
or  mineralogical,  and  the  organic  or  biological  kingdoms, 
the  division  of  the  latter  into  vegetable  and  animal  being 
a  subordinate  one.  The  natural  history  or  physiography 
of  the  inorganic  kingdom  takes  cognizance  of  the  sensible 
characters  of  chemical  species,  and  gives  us  descriptive 
and  systematic  mineralog}'',  which  have  hitherto  been 
restricted  to  native  species,  but  in  their  wider  sense 
include  all  artificial  species  as  vrell.  The  study  of  native 
mineral  species,  their  aggregations,  and  their  arrangement 
as  constituents  of  our  planet,  is  the  object  of  geognosy 
and  of  geography.  The  physiography  of  other  worlds 
gives  rise  to  descriptive  astronomy. 

27 


28 


THE   ORDER   OF   THE   NATURAL   SCIENCES. 


[II. 


H 


§  8.  The  natural  philosophy  of  the  inorganic  kingdom, 
or  mineral  physiology,  is  concernetl,  in  the  lirst  place, 
with  what  is  generally  called  dynamics  or  physics,  includ- 
ing the  phenomena  of  ordinary  motion,  sound,  tempera- 
ture, radiant  energy,  electricity  and  magnetism.  Dynam- 
ics, in  the  abstract,  regards  matter  in  general,  without 
relation  to  species;  chemism  generates  therefrom  mine- 
ralogical  or  so-called  chemical  species,  which,  theoreti- 
cally, may  be  supposed  to  be  formed  from  a  single  ele- 
mental substance,  or  materia  prima,  by  the  chemical 
process.  Dynamics  and  chemistry  build  up  our  inorganic 
world,  giving  rise  to  geogeny  and,  as  applied  to  other 
worlds,  to  theoretical  astronomy. 

§  4.  Proceeding  now  to  the  organic  kingdom,  its  physi- 
ographical  study  leads  us  first  to  organography,  and  then 
to  descriptive  and  systematic  botany  and  zoology,  two 
great  subdivisions  of  natural  history.  Coming  next  to 
consider  the  physiological  aspect  of  organic  nature,  we 
note,  besides  the  dynamical  and  chemical  activities  mani- 
fested in  the  mineral,  other  and  higher  ones,  wliich  char- 
acterize the  organic  kingdom.  On  this  higher  plane  of 
existence  are  found  portions  of  matter  which  have  become 
individualized,  exhibit  irritability,  the  power  of  growth 
by  assimilation,  and  of  reproduction,  and,  moreover,  estab- 
lish relations  with  the  external  world  by  the  development 
of  organs,  all  of  which  characters  are  foreign  to  the 
mineral  kingdom.  These  new  activities  are  often  desig- 
nated as  vital,  but  since  this  word  is  generally  "made  to 
include  at  the  same  time  other  manifestations  which  are 
simply  dynamical  or  chemical,  I  have  elsewhere  proposed 
for  the  activities  characteristic  of  the  organism  the  term 
biotics  [Sioiiy.ug,  pertaining  to  life). 

§  5.  The  philosophy  of  matter  in  the  abstract  is  dynami- 
cal, that  of  mineral  species  is  both  dynamical  and  chemi- 
cal, while  that  of  organized  forms  is  at  once  dynamical, 
chemical,  and  biotical.  The  study  of  the  biotical  activi- 
ties of  matter  leads  to  organogeny  and  morphology,  while 


m 


THE  OKDER  OF  THE  NATUUAL  SCIENCES. 


29 


the  relations  of  organisms  to  one  another,  and  to  the 
inorganic  kingdom,  give  ns  pliysiological  botany  and 
zoJJlogy.  AVe  thus  arrive  at  a  com[)reheiisive  and  simple 
scheme  for  the  classification  of  the  natural  sciences,  which 
is  set  forth  in  the  subjoined  table :  — 


Natural  Sciences. 

Inoroanic  Nature. 

Organic  Nature. 

DESCRU'TIVK. 

Mineral  PiiYSioaRAPHY. 

BlOlMIYBIOGRAPHY. 

General  Physiography 

Descriptive  and  Systematic 

Organography  ; 

or 

Mineralogy  ; 

Descriptive  and  Systema- 

Natural  History. 

Geognosy ;  Geography ; 

tio  liotauy  and  Zoology. 

' 

Descriptive  Astronomy. 

PuiLosopnicAii. 

Mineral  Physiology. 

BlOPUVSIOLOOY. 

General  Physiology 

Dynamics  or  Physics; 

Biotics. 

or 

Chemistry. 

Organogeny ;  Morphology; 

Natural  Philosophy, 

Geogeny;  Theoretical 

Physiological 

Astronomy. 

Botany  and  ZoOlogy. 

■  1^ 


*%<? 


in. 

THE   CHEMICAL   AND   GEOLOGICAL   RELATIONS   OP 

ATMOSPUEIIE.* 


THE 


In  addition  to  the  detnils  given  in  tlie  footnote,  it  need  only  be  Hnid  that  this 
paper  was  publlBlied  in  the  American  Journal  of  Science  for  RIny,  1880  ([111.]  xix., 
34!>-3C3),  and  that  a  furthur  dlsciieNlon  of  8ome  of  the  questionM  r.iised  lieruli.  will  be 
found  in  the  following  essay  on  Celestial  Chemistry  fk'om  the  Time  of  >.OiVton. 

§  1.  Questions  concerning  the  condition  of  the  terres- 
trial atmosphere  in  former  periods  of  the  eartii's  history, 
and  its  geological  relations,  have  occupied  the  attention 
of  naturalists,  physicists,  and  chemists.  Brongniart  long 
since  suggested  that  the  abundant  vegetation  of  the  coal 
period  indicated  the  existence  of  a  large  proportion  of 
carbonic  acid  in  the  air  at  that  time.  Ebelmen,  howe/er, 
appears  to  have  been  the  first  to  clearly  understand  the 
great  geological  significance  of  the  atmosphere,  and  in  his 
two  remarkable  memoirs  on  the  decomposition  of  :  >ck8, 
published  in  the  Annales  des  Mines  in  1845  and  1847,t 
treated  the  subject  in  its  atmospheric  relations  with  much 
research  and  philosophic  breadth.  Starting  from  the 
chemical  changes  of  crystalline  silicate  rocks,  he  consid- 
ered both  the  conversion  of  feldspars  into  kaolin,  and  the 

*  A  summary  of  the  views  presented  in  this  memoir  was  given  at 
Dublin,  in  August,  1878,  before  the  British  Association  for  tlie  Advance- 
ment of  Science.  An  abstract  thereof  appeared  in  the  Proceedings,  and 
will  be  found  in  Nature  for  Aug.  29,  1878  (vol.  xviii.,  p.  475).  The 
principal  conclusions  of  the  memoir  are  also  embodied  in  a  communica- 
tion made  by  the  author  to  the  French  Academy  of  Sciences,  and  pub- 
lished in  the  Comptes  Rendus  of  Sept.  23,  1878  (vol.  Ixxxvii.,  p.  4.'>2). 
They  will  moreover  be  found  set  forth  in  the  preface  to  a  second  edition 
of  the  writer's  Chemical  and  Geological  Essays  (pp.  ix.-xix.)  published 
in  the  spring  of  the  same  year. 

t  Fourth  Series,  vols.  vii.  and  xiii.  These  memoirs  will  also  be  found 
in  the  Receuil  des  Trav.  Sclent,  de  M.  Ebelmen;  Paris,  1855,  vol.  ii., 
pp.  1-79. 

80 


III.] 


RELATIONS   OF   TIIK   ATMOHIMIKIIK. 


81 


decay  of  protoxide-silicates,  such  as  aniijliibolo  and  olivine. 
Tiio  sub-aerial  decoinjxKsition  of  the  fehlspars  had  already 
been  shown  by  IJerthier  to  result  in  the  separation,  in  a 
soluble  form,  of  the  protoxide-base ;  together  with  a  por- 
tion of  silica,  from  an  insoluble  aluminous  silicate  of 
definite  composition.  The  analyses  of  Ebelmen  now 
established  the  fact  that  the  protoxide-silicates  just  men- 
tioned, lose,  under  similar  conditions,  the  whole  of  their 
lime  and  magnesia,  and  ncirly  the  whole  of  their  silica, 
leaving  little  behind  save  the  higher  oxides  resulting 
from  the  fixation  of  atmospheric  oxygen  by  the  ferrous 
and  manganous  oxides  of  the  silicates ;  the  soluble  bases 
being  in  all  rases  removed  by  atmospheric  waters  in  the 
form  of  carbonates.  Such  a  decomposition  of  these  sili- 
cates shows  that  the  removal  of  silica  in  soluble  form  does 
not  depend  on  the  intervention  of  alkalies. 

§  2.  The  atmosphere  of  our  earth,  at  a  pressure  of  760 
millimetres,  has  a  weight  of  10,333  kilograms  to  the 
square  metre,  of  which  the  oxygen  equals  2376,  and  the 
carbonic  dioxide  (if  we  take  Boussingault  and  Ldwy's 
determination  of  four  and  a  half  parts  in  10,000  parts  by 
weight)  4.64*  kilograms.  The  alkali  of  100  parts  of 
orthoelase  would  require  for  its  neutralization  7.8  parts 
of  carbonic  dioxide,  so  that  a  cubic  metre  of  this  silicate, 
of  specific  gravity  2.5,  would,  by  the  calculation  of  Ebel- 
men, fix,  in  the  process  of  decay,  195  kilograms  of  the 
gas.  From  this  it  results  that  a  layer  of  orthoelase  over 
the  earth  of  0.0238  metre,  or  one  of  less  than  1.0  metre 
over  one-fortieth  of  its  surface,  would,  in  its  decomposi- 
tion, absorb  the  whole  amount  of  this  gas  now  present  in 
the  atmosphere.  Ebelmen  further  calculated  that  the 
formation  of  a  layer  of  kaolin  by  this  process,  500  metres 
in  thickness,  would  require  an  amount  of  carbonic  dioxide 
equal  to  many  times  the  weight  of  the  present  atmos- 
phere. 

*  This,  by  an  error  in  Ebelmen's  memoir,  is  given  as  only  1.24  kilo- 
gr.ims. 


32 


THE  CHEMICAL  AND   GEOLOGICAL 


[in. 


iiiil  I 


§  3.  "We  have  repeated  and  extended  these  calculations, 
with  revised  molecular  weights,  and  with  the  following 
results :  A  cuhic  metre  of  orthoclase,  with  a  density  of 
2.5,  and  containing  theoretically  16.9  per  cent  of  potash, 
equivalent  to  7.89  of  carbonic  dioxide,  would  absorb  in 
kaolinization  197.3  kilograms  of  this  gas,  while  a  cubic 
metre  of  albite  of  density  2.6,  containing  11.8  of  soda, 
equivalent  to  8.37  of  carbonic  dioxide,  would  require  not 
less  th:i,;i  217.6  kilograms  of  the  same.  The  figure  of  195 
kilogram  is,  adopted  by  Ebelmen,  was  thus  below  the  truth, 
and  we  may,  in  view  of  the  considerable  proportion  of 
soda-feldspar  in  the  oldest  crystalline  rocks,  convenie  tly 
assume  200  kilograms  as  the  amount  of  carbonic  dioxide 
required  to  unite  with  the  alkali  from  a  cubic  metre  of 
orthoclase  or  albite,  and  form  therewith  a  neutral  car- 
bonate. 

§  4.  In  such  a  decomposition,  100  parts  of  orthoclase 
give  theoretically  about  46.5  parts  of  kaolin,  so  that  1.0 
metre  in  thickness  of  orthoclase  of  the  above  density 
should  yield  0.447  metre  of  kaolin  of  density  2.6.  If  we 
assume  this  process  to  have  consumed  for  a  cubic  metre 
or  2500  kilograms  of  orthoclase,  200  of  carbonic  dioxide, 
we  find  that  a  layer  of  51.66  metres  of  orthoclase,  or  its 
equivalent  of  quartzo-feldspathic  rock,  in  undergoing  the 
same  change,  would  absorb  10,333  kilograms  of  this  gas, 
equal  to  the  entire  weight  of  the  present  atmospheric 
column,  and  would  yield  a  layer  of  pure  kaolin  23.7 
metres  in  thickness.  The  production  of  a  stratum  of 
kaolin  500  meters  in  thickness  over  the  whole  surface  of 
the  globe,  would  thus  require  an  amount  of  carbonic 
dioxide  equal  to  more  than  twenty-one  times  the  entire 
weight  of  our  present  atmosphere. 

§  5.  The  absorption  of  this  gas  in  the  decay  of  silicates 
like  hornblende,  pyroxene,  and  olivine  is  far  greater.  If 
we  assume,  for  convenience,  a  hornblende  containing  20.0 
per  cent  of  magnesia,  and  14.0  of  lime,  with  a  density  of 
3.0  (which  figures  are  not  above  the  average),  we  find 


ni.] 


RELATIONS   OF  THE  ATMOSPHERE. 


33 


n 
ic 


ot 
95 
th, 
of 

tiy 

dde 
3  of 
car- 

slase 

ti.o 

nsity 

f  we 

netre 

ixide, 

,r  its 

ig  the 

U  gas, 

|)lierio 
23.T 

km  of 
[ace  of 
•bonic 
lentire 

ticates 

3r.  If 
kg  20.0 
[Sty  of 
re  find 


that  it  will  require  33.0  per  cent,  or,  in  round  numbers, 
one-third  its  weight  of  carbonic  dioxide  to  convert  these 
two  bases  into  neutral  carbonates ;  so  that  a  metre-cube 
of  hornblende,  weighing  3000  kilograms,  would  consume 
not  less  than  1000  Lllograms  of  carbonic  dioxide.  In 
other  terms,  the  decay  of  10^  metres  of  such  hornblende 
(or  its  equivalent  in  hornblendic  rock)  would  absorb 
10,333  kilograms,  or  a  whole  atmosphere  of  this  gas,  being 
five  times  as  much  as  is  taken  up  in  the  kaolin izatiou  of 
the  same  volume  of  orthoclase. 

§  6,  The  hornblendes  in  question  are  seldom  without 
several  hundredths  of  iron  as  ferrous  oxide,  which  is 
peroxidized  in  the  process  of  decay,  and,  with  a  little 
silica,  is  the  chief  insoluble  residue  in  the  case  of  non- 
aluminous  hornblendes.  In  this  connection,  we  revert  to 
a  farther  calculation  by  Ebelmen,  who  pointed  out  that 
the  conversion  of  21,357  kilograms  of  ferrous  oxide  into 
23,750  kilograms  of  ferric  oxide  would  consume  the  whole 
of  the  2373  kilograms  of  oxygen  contained  in  the  present 
atmosphere ;  so  that  if  we  suppose  the  existence  over  the 
whole  earth  of  1000  metres  of  sediments  derived  from  the 
decay  of  crystalline  rocks,  and  containing  only  one  per 
cent  of  ferric  oxide  thus  formed,  this  amount  would  equal 
25,000  kilograms  per  square  metre  of  surface,  requiring 
for  its  production  from  ferrous  oxide  the  absorption  of  a 
quantity  of  oxygen  more  than  equal  to  that  now  contained 
in  our  atmosphere. 

§  7.  Ebelmen,  at  the  same  time,  referred  to  the  vrell- 
known  deoxidation  of  carbonic  dioxide  by  growing  vege- 
tation, and  also  to  the  reduction,  by  decaying  organic 
matters,  of  sulphates  to  sulphides,  with  reproduction  of 
carbonic  dioxide,  through  which  the  generation  of  metallic 
sulphides  in  ijature  gives  to  the  atmosphere,  in  union  with 
carbon,  a  portion  of  the  oxygen  previously  combined  with 
sulphur  and  with  the  metals. 

The  following  calculations  may  serve  to  bring  still  more 
fully  before  us  the  great  geological  significance  of  these 


34 


THE  CHEMICAL  AND  GEOLOGICAL 


[UI. 


k 


atmospheric  changes.  The  weight  of  a  layer  of  pure  car- 
bon, with  a  density  of  1.2p  and  a  thickness  of  0.7  metre, 
would  require  for  its  conversion  into  carbonic  dioxide  the 
whole  of  the  oxygen  of  our  present  atmosphere.  The 
separation  of  such  an  amount  of  carbon  by  the  process  of 
vegetable  growth  must  therefore  have  liberated  the  same 
volume  of  oxygen.  Again,  a  stratum  of  carbonate  of  lime 
of  specific  gravity  2.7,  covering  the  earth  with  a  thick* 
ness  of  8.69  metres  (or  one  of  dolomite  of  2.85,  and  7.58 
metres  thick),  would  contain  an  amount  of  carbonic  diox- 
ide equal  in  weight  to  the  present  atmosphere.* 

§  8.  It  was  in  view  of  these  processes  that  Ebelmen 
declared,  in  1845,  that  "the  decomposition  and  the  repro- 
d action  of  certain  mineral  species  very  abundant  on  the 
surface  of  the  globe  corresponds  to  important  modifica- 
tions in  the  composition  of  the  atmosphere."  He  farther 
said,  "Many  circumstances  tend  to  prove  that  in  ancient 
geological  periods  the  atmosphere  was  denser,  and  more 
rich  in  carbonic  acid,  and  perhaps  in  oxygen,  than  at  pres- 
ent. To  a  greater  weight  of  the  atmospheric  envelope 
would  correspond  a  stronger  condensation  of  the  solar 
heat,  anu  atmospheric  phenomena  of  a  much  greater 
intensity."  f  Similar  conclusions  with  regard  to  the 
physical  relations  of  a  denser  primeval  ainosphere  were 
subsequently  announced  by  the  late  Edwi'i  B.  Hunt,  in 
an  essay  on  Terrestrial  Thermotics,  presented  to  the 
American  Association  for  the  Advancement  of  Science, 
in  1849,  and  published  in  its  Proceedings  for  that  year, 
page  135. 

§  9.  We  may  get  a  clearer  notion  of  the  problem  before 
us  by  inquiring  into  the  probable  amounts  of  carbonic 
dioxide  which  have,  in  past  ages,  been  abstracted  from 
the  atmosphere.      In   a  communication   to   the   British 


*  T.  Sterry  Hunt  on  the  Primeval  Atmosphere,  Proc.  Amer.  Assoc. 
Adv.  Science,  1860,  and  Can.  Naturalist,  II.,  iil.,  118. 

t  Ann.  des  Mines,  IV.,  vii.,  05;  also  Receuil  dea  Trav.  Sclent,  de 
M.  Ebelmen.  vol.  ii.,  p.  65. 


^ 


ui. 


III.] 


RELATIONS  OF  THE  ATMOSPHERE. 


35 


tre, 
tlie 
The 
ss  of 
same 
lime 

thick 
L7.58 
;  diox- 

3elmen 

!  tepro- 
onthe 

lodifica- 

;  farther 
ancient 

nd  more 

1  at  pres- 

I  envelope 

the  solar 
crreater 
to  the 
lere  were 
Hxnat,  in 
a  to   the 
£  Science, 
that  year, 

,lem  heiore 
i  carbonic 
vcted  from 
\xQ  British 

Amer.  Assoc. 
Lv.  Sclent,  de 


Association  for  the  Advancement  of  Science,  in  1877,* 
Mr.  J.  L.  Mott  concludes,  as  the  result  of  calculations, 
that  the  average  amount  of  unoxidized  carbon  to  a  square 
mile  of  the  earth's  crust  cannot  be  less,  and  is  probably 
many  times  greater  than  3,000,000  tons ;  while  a  layer  of 
0.7  metres  of  carbon  of  density  1.25  (about  that  of  coal), 
whicli  we  have  calculated  to  be  equal  to  the  total  atmos- 
pheric oxygen,  would  weigh  only  about  2,200,000  tons  to 
the  square  mile.  Mr.  Mott  rightly  argues  that  the  pres- 
ence in  the  atmosphere  of  so  great  an  amount  of  carbon 
in  the  form  of  dioxide  would  imply  a  condition  of  things 
incompatible  with  the  existence  of  animal  life,  and  at  the 
same  time  concludes  that  its  deoxidation  would  yield  an 
excessive  amount  of  oxygen.  He  is  hence  led  to  assume 
the  existence  in  the  earth  of  a  constant  amount  of  carbon, 
which  is  subject  to  an  annual  subterranean  oxidation 
equal  to  the  amount  of  carbon  annually  removed  by  vege- 
tation; the  source  of  the  original  amount  of  carbon  being, 
in  his  hypothesis,  left  unexplained. 

§  10.  While  some  have  imagined  an  inorganic  origin 
to  the  carbon  found  in  the  form  of  graphite,  and  even  to 
petroleum  and  to  coal,  sound  reasoning  is,  we  think,  on 
the  side  of  those  who,  starting  from  the  conception  of  an 
originally  oxidized  globe,  see  no  evidence  of  any  process 
of  deoxidation  therein  which  does  not,  directly  or  indi- 
rectly, depend  upon  vegetable  life,  and  hence  assign  an 
organic  origin  to  all  carbons  and  hydrocarbons.  When 
we  take  into  account  the  vast  amounts  of  these,  from  the 
graphite  of  Eozoic  times  to  the  coals,  lignites,  and  petro- 
leums of  the  Tertiary,  we  can  scarcely  doubt  that  the 
total  amount  of  carbon  which  has  been  reduced  from  car- 
bonic dioxide  is  equal  to  many  times  the  equivalent  of  the 
oxygen  now  present  in  the  atmosphere.  Whether  the 
great  excess  of  oxygen  thus  liberated  may  perhaps  have 
been  absorbed  in  the  production  of  ferric  oxide,  as  above 
indicated,  is  a  part  of  the  problem  before  us. 

*  Nature,  vol.  xvL,  p.  406. 


36 


THE  CHEMICAL  AND  GEOLOGICAL 


l!  I; 


11 


! 


PII. 


§  11.  It  may  here  be  noted  that  in  addition  to  the 
fossil  carbonaceous  bodies  already  mentioned,  the  rocky 
strata  of  the  earth  include  great  thicknesses  of  pyroschists, 
which  are  argillaceous  sediments  more  or  less  impregnated 
with  hydrocarbonaceous  matters  allied  to  coal  in  compo- 
sition. To  give  a  single  example,  Newberry  estimates  the 
proportion  of  such  matters  diffused  through  the  three 
hundred  or  four  hundred  feet  of  Devonian  black  shales 
which  underlie  the  eastern  half  of  Ohio,  to  equal  fifteen 
per  cent,  and  to  be  equivalent  to  a  layer  of  coal  fifty  feet 
in  thickness  over  the  whole  area.* 

In  this  connection  it  must  be  considered  that  the  chem- 
ical composition  of  the  various  hydrocarbonaceous  fossil 
substances  implies  a  deoxidation  not  only  of  carbonic 
dioxide  but  of  water.  The  amount  of  liberated  oxy- 
gen from  the  latter  would  equal,  for  the  different  coals 
and  asphalts,  from  one-eighth  to  one-fourth,  and  for  the 
petroleums,  one-half  of  that  set  free  in  the  deoxidation 
of  the  carbon  which  these  hydrocarbonaceous  bodies  con- 
tain. 

§  12.  The  amount  of  carbon  removed  from  the  atmos- 
phere in  a  deoxidized  form  by  vegetation  is,  however,  small 
when  compared  with  that  which  has  been  absorbed  during 
the  decomposition  of  silicates,  and  is  now  fixed  as  insolu- 
ble carbonates,  chiefly  in  the  form  of  limestones  and  dolo- 
mites. That  both  the  alkaline  carbonates  liberated  in  the 
decay  of  feldspars,  and  the  magnesian  carbonate  set  free 
in  like  manner  fron  magnesian  silicates,  must  decompose 
the  chlorid  of  calcium  contained  in  the  primitive  ocean, 
tliereby  giving  rise  to  alkaline  and  magnesian  chlorides 
on  the  one  hand,  and  to  carbonate  of  lime  on  the  other, 
is  a  consequence  which  seems  to  have  escaped  Ebelmen, 
and  was  pointed  out  by  the  present  writer  in  1858.  In 
1862,  however,  there  was  opened  a  sealed  packet  which 
had  been  in  1844  deposited  by  Cordier  with  the  French 
Academy  of  Sciences,  and  was  found  to  contain  views  as 

*  Geology  of  Ohio,  vol.  I.,  page  162. 


ItELATIONS  OF  THE  ATMOSPHERE. 


87 


to  the  origin  of  limestones  and  of  sea-salt  similar  to  those 
just  stated.*  Thus,  in  the  present  state  of  our  knowledge, 
we  conclude  that  all  carbonates  of  lime,  whether  directly- 
formed  by  the  decay  of  calcareous  silicates,  or  indirectly 
through  the  intervention  of  carbonates  of  magnesia  or 
alkalies,  derive  their  carbonic  dioxide  from  the  atmos- 
phere. The  same  must  be  said  for  the  dolomites,  magne- 
sites,  and  siderites. 

§  13.  We  have  already  shown  that  a  weight  of  carbonic 
dioxide  equal  to  more  than  twenty-one  times  that  of  our 
present  atmosphere  would  be  absorbed  in  the  production 
from  orthoclase  of  a  layer  of  kaolin  extending  over  the 
earth's  surface  with  a  thickness  of  five  hundred  metres, 
an  amount  which  evidently  represents  but  a  small  propor- 
tion of  the  results  of  feldspathic  decay  in  the  sedimentary 
strata  of  the  globe.  The  aluminous  silicates  in  the  oldest 
crystalline  rocks  occur  in  the  forms  of  feldspars  and  re- 
lated species,  and  are,  so  to  speak,  saturated  with  alkalies 
or  with  lime.  It  is  only  in  more  recent  formations  that 
we  find  aluminous  silicates  either  free  or  with  reduced 
amounts  of  alkali,  as  in  the  argillites  and  clays,  in  mica- 
ceous minerals  like  muscovite,  margarodite,  damourite, 
and  pyrophyllite,  and  in  kyanite,  fibrolite,  and  andalusite, 
all  of  which  we  regard  as  derived  indirectly  from  the 
more  ancient  feldspars.f 

§  14.  It  has  been  shown  that  the  disengagement  of  the 
carbonic  dioxide  from  a  layer  of  limestone  covering  the 

*  Hunt,  Chem.  and  Geol.  Essays,  pp.  2  and  20. 

t  These  considerations,  and  tlielr  stratigraphical  bearings,  first  set  forth 
In  1863  (Chem.  and  Geol.  Essays,  pp.  27  and  28),  will  be  found  further 
developed  in  the  writer's  report  on  Azoic  Koeks,  2d  Geol.  Survey  of 
Penn.,  1878,  p.  210.  It  is  a  question  how  far  the  origin  of  the  various 
crystalline  aluminous  silicates  named  above  is  to  be  sought  in  a  process 
of  diagenesis  in  ordinary  aqueous  sediments  holding  the  ruins  of  more  or 
less  completely  decayed  feldspars.  Other  aluminous  rock-forming  sili- 
cates, such  as  chlorites  and  magnesian  micas,  are  however  connected, 
througli  aluminiferous  amphiboles,  with  the  non-aluminous  magnesiau 
silicates,  and  to  all  these  various  magnesian  minerals  a  vei7  dilferent 
origin  must  be  assigned.  [See  in  this  connection  Essay  V.,  The  Origin 
of  Crystalline  Kocks,  etc.] 


38 


THE  CHEMICAL  AND   GEOLOGICAL 


tm. 


^      '  M 


II 


i 


earth's  surface  with  a  thickness  of  8.69  metres,  would 
double  the  weight  of  the  atmosphere.  The  existence  of 
vast  formations  of  limestone  and  dolomite,  often  many 
hundred  metres  in  thickness,  throughout  all  geological 
periods,  will,  it  is  believed,  justify  the  conclusion  that  the 
carbonates  of  the  earth's  crust  are  equal  to  a  continuous 
layer  of  limestone  869  metres  thick,  and  probably  to 
more  than  double  this  amount.  From  this  it  would 
follow  that  the  earth  contains,  fixed  in  the  form  of  car- 
bonates, a  quantity  of  carbonic  dioxide,  which,  if  liber- 
ated in  a  gaseous  form,  would  be  equal  in  weight  to  one 
hundred  if  not  to  two  hundred  atmospheres  like  the 
present.  A  considerable  portion  of  this  was  doubtless 
absoibed  at  an  early  period  in  the  history  of  our  globe, 
since  the  limestones  of  the  Eozoic  age  are  of  great  thick- 
ness, and  those  of  more  recent  times  have  been  in  part 
formed  by  the  solution  and  re-deposition  of  portions  of 
these  older  limestones. 

§  15.  The  question  now  arises,  whence  came  this  enor- 
mous volume  of  carbonic  dioxide  which,  since  the  dawn 
of  life  on  our  planet,  has  been  fixed  in  the  form  of  carbon 
and  carbonates  ?  The  presence  of  even  a  small  proportion 
of  it  at  any  one  time  in  the  terrestrial  atmosphere  is  evi- 
dently incompatible  with  the  existence  of  vegetable  and 
animal  life,  and  it  may  be  added  that  the  pressure  of 
a  column  of  this  gas  less  than  the  minimum  of  100  atmos- 
pheres which  we  have  supposed,  would  suffice,  at  ordinary 
temperatures,  for  its  partial  liquefaction;  the  tension  of 
liquid  carbonate  dioxide  at  30°.7  C.  being,  according  to 
Mareska  and  Donny,  but  eighty  atmospheres.  We  are 
therefore  forced  to  the  conclusion  that  this  gas  was  gradu- 
ally supplied  from  a  source  either  within  tlie  earth  or 
beyond  our  atmosphere. 

§  IG.  The  difficulties  of  this  problem  were  not  over- 
looked by  Ebelmen,  though  he  apparently  faile'l  to  recog- 
nize tneir  full  weight.  He  takes  care  to  remark :  "  I  do 
not  pretend  that  this  immense  proportion  of  carbonic  acid 


m>i 


KELAL    WS  OF  THE  ATMOSPHEUE. 


89 


ever  made  part,  at  any  one  time,  of  the  terrestrial  atmos- 
phere. ...  I  see  in  volcanic  phenomena  the  principal 
agent  which  restores  to  the  atmosphere  t'he  carbonic  acid 
which  the  decomposition  of  rocks  removes  from  it."  He 
then  inquires  whether  the  carbonic  acid  (carbonic  dioxide) 
evolved  from  the  earth's  interior,  comes  from  the  decom- 
position of  carbonates  at  great  depths  and  high  tempera- 
tures by  reactions  with  silicious  matters,  or  whether  we 
may  imagine,  with  Elie  de  Beaumont,  the  existence  of  an 
immense  reservoir  of  carbonic  acid  dissolved  in  the  sup- 
posed liquid  interior  of  the  earth  as  oxygen  is  held  in 
fused  litharge  or  in  molten  silver.  In  either  case,  remarks 
Ebelmen,  the  cessation  of  volcanic  phenomena  would  be 
followed  by  the  removal  from  the  atmosphere  of  the  last 
traces  of  carbonic  acid,  a  process  which  would  entail  the 
extinction  of  all  vegetable  and  animal  life. 

§  17.  Of  these  two  suggested  sources  of  the  terrestrial 
carbonic  dioxide,  a  little  reflection  will  show  that  although 
the  first  is  doubtless  a  true  one,  and  will  serve  to  account 
for  that  which  is  so  often  disengaged  from  the  earth,  both 
in  volcanic  and  non-volcanic  regions  (having  a  similar 
origin  to  the  chlorhydric,  sulphuric  and  boric  acids 
evolved  under  analogous  conditions  —  namely,  the  decom- 
position of  saline  compounds  of  aqueous  origin),*  it  by  no 
means  meets  the  requirements  of  the  problem.  As  pre- 
ceding calculations  have  shown,  it  is  not  a  question  of  a 
small  amount  of  carbonic  dioxide  alternately  removed 
from  our  atmosphere  by  sub-aerial  reactions  and  restored 
to  it  by  subterranean  processes,  but  of  a  vast  quantity  of 
this  gas  which,  at  one  time  or  another,  has  existed  in  the 
terrestrial  atmosphere,  but  is  now  removed  from  the  aerial 
circulation  and  locked  up  in  the  form  of  carbonates. 

§  18.  As  regards  the  second  source  of  carbonic  dioxide, 
suggested  by  Ebelmen  after  ^lie  de  Beaumont,  it  is,  un- 
like tlie  last,  purely  hypothetical.  That  the  globe  has  a 
molten  interior  is,  in  the  present  state  of  our  knowledge 

*  Hunt,  Chem.  and  Geol.  Essays,  pp.  8  and  111. 


40 


THE  CHEMICAL  AND  GEOLOGICAL 


[III. 


;ii-     ,       ,| 


of  terrestrial  physics,  very  improbable,  and  if  such 
exists,  the  notion  that  it  intervenes  directly  in  volcanic 
phenomena  is  still  more  so.  The  suggestion  that  such 
a  molten  interior  might  liold  dissolved  a  great  volume 
of  carbonic  dioxide  appears,  moreover,  to  be  inconsistent 
with  what  we  know  of  the  behavior  of  furnace-slags, 
which,  though  formed  in  atmospheres  highly  chnrged  with 
this  gas,  do  not,  as  shown  by  their  behavior  in  cooling, 
hold  it  in  solution.  The  tendencies  of  modern  geological 
thought  and  investigation,  it  may  be  said,  lead  to  the 
conclusion  that  the  seat  of  volcanic  phenomena  is  to  be 
found  in  sedimentary  strata,*  and  that  although  the 
earth's  interior  intervenes  as  a  source  of  heat,  tiie  car- 
bonic dioxide  disengaged  from  its  crust  is  derived,  as  in 
the  first  hypothesis  mentioned  by  Ebelmen,  from  the  de- 
composition of  carbonates  previously  generated  by  sub- 
aerial  re-actions. 

§  19,  The  problem  still  before  ns  is  then  to  find  the 
source  of  the  vast  amount  of  carbonic  dioxide  continuously 
supplied  to  the  atmosphere  throughout  the  geologic  ages, 
and  as  continuously  removed  therefrom,  and  fixed  in  the 
form  of  carbonaceous  matters  and  limestones.  We  have 
shown  reasons  for  rejecting  the  theory  which  would  derive 
this  supply  either  from  the  earth's  interior  or  from  its  own 
primal  atmosphere,  tnd  must  therefore  look  for  it  to  an 
extra-terrestrial  source.  The  new  hypothesis,  which  we 
here  advance,  starts  with  the  assumption  that  our  atmos- 
phere is  not  primarily  terrestrial  but  cosmical,  and  that 
the  air,  together  with  the  water  surrounding  our  earth 
(whether  in  a  liquid  or  a  vaporous  state),  belongs  to  a 
continuous  elastic  medium  which,  extending  throughout 
the  interstellary  spaces,  is  condensed  around  attracting 
bodies  in  amounts  proportional  to  their  mass  and  tempera- 
ture. This  universal  atmosphere  (if  the  expression  may 
be  permitted)  would  then  exist  in  its  most  attenuated 
form  in  the  regions  farthest  distant  from  these  centres 
*  Chem.  and  Geol.  Essays,  pp.  59-67;  also,  farther,  V.  §  127. 


lU.] 


RELATIONS  OF  THE  ATMOSPHERE. 


41 


of  attraction ;  while  any  change  in  the  gaseous  envelope 
of  any  globe,  whether  by  the  absorption  or  condensation, 
or  by  the  disengagement  of  any  gas  or  vapor,  would,  by 
the  laws  of  diffusion  and  static  equilibrium,  be  felt  every- 
where throughout  the  universe. 

§  20.  The  precipitation  of  water  at  the  surface  of  a 
cooling  globe,  and  its  chemical  or  mechanical  fixation 
there,  would  thus  diminish  the  proportion  of  gaseous 
water  throughout  all  space.  The  oxygen  liberated  in  the 
growth  of  terrestrial  vegetation  would  be  shared  with  the 
remotest  spheres,  while  the  condensatioi:  of  carbonic 
dioxide  at  the  surface  of  our  own  or  any  other  planet, 
would  not  only  bring  in  a  supply  of  this  gas  from  the 
atmospheres  of  other  bodies,  but  by  reducing  the  total 
amount  of  it,  would  diminish,  pro  tanto,  the  baro- 
metric pressure  at  the  surface  of  this  and  of  all  other 
worlds. 

§  21.  The  hypothesis  here  advanced  is  not  wholly  new. 
Sir  William  R.  Grove,  in  1842,  suggested  that  the  medium 
of  light  and  heat  may  be  "  a  universally  diffused  matter," 
and  subsequently,  in  1843,  in  his  celebrated  Essay  on  the 
Correlation  of  Physical  Forces,  in  the  chapter  on  Light, 
concludes,  with  regard  to  the  atmospheres  of  the  sun  and 
planets,  that  there  is  no  reason  why  these  atmospheres 
"should  not  be,  with  reference  to  each  other,  in  a  state  of 
equilibrium.  Ether,  which  term  wo  may  apply  to  the 
highly  attenuated  matter  existing  in  the  interplanetary 
spaces,  being  an  expansion  of  some  or  all  of  these  atmos- 
pheres, or  of  the  more  volatile  portions  of  them,  would 
thus  furnish  matter  for  the  transmission  of  the  modes  of 
motion  which  we  call  light,  heat,  etc.,  and  possibly  minute 
portions  of  these  atmospheres  may,  by  gradual  accretions 
and  subtractions,  pass  from  planet  to  planet,  forming  a  link 
of  material  communication  bettveen  the  distant  monads  of 
the  universe.^'  Subsequently,  in  his  address  as  President 
of  the  British  Association  for  the  Advancement  of  Sci- 
ence, in  1866,  Grove  further  suggested  that  this  diffused 


42 


THE  CHEMICAL  AND  GEOLOGICAL 


[III. 


ii 


U    '       Jl 


matter  might  become  a  source  of  solar  heat,  inasmuch  as 
the  sun  "may  condense  gaseous  matter  at,  i,t  travels  in 
space,  and  so  heat  may  be  produced." 

§  22.  Tl>is  bold  speculation  of  a  universally  diffused 
matter,  consiituting  an  interstellary  medium,  though  thus 
repeatedly  insisted  upon  by  Grove,  lias  passed  almost  un- 
noticed. It  seems  to  have  been  unknown  to  Mr.  W.  Mat- 
tieu  Williams,  who,  in  1870,  published  his  very  ingenious 
work  entitled  "The  Fuel  of  the  Sun,"*  which  is  base<l  on 
a  similar  conceptiop,  without  citing  in  support  of  it  the 
high  authority  of  Grove.  The  solar  heat,  according  to 
Williams,  is  maintained  by  the  oun's  condensation  of  the 
attenuated  matter  everywhere  encountered  by  that  body 
in  its  motion  thiough  interstellary  space.  The  irregular 
movements  impressed  upon  the  sun  by  the  varying  attrac- 
tions of  the  planets  —  stirring  up  and  intermingling  the 
different  strata  of  the  solar  atmosphere,  and  producing  the 
great  perturbations  therein  of  which  the  telescope  affords 
evidence  —  are,  in  his  hypothesis,  the  efficient  agents  in 
this  process.  The  diffused  matter  or  ether,  which  is  the 
recipient  of  the  heat-radiations  of  the  universe,  is  thereby 
drawn  into  the  depths  of  the  solar  mass;  expelling  thence 
the  previously  condensed  and  thermally  exhausted  ether, 
it  becomes  compressed,  and  gives  up  its  heat,  to  be,  in 
turn,  itself  driven  out  in  a  rarefied  and  cooled  state,  and 
to  absorb  a  fresh  supply  of  heat,  which  he  supposes  to  be 
in  this  way  taken  up  by  the  ether,  and  again  concentrated 
and  re-distributed  by  the  suns  of  the  universe.  (Loc.  cit., 
chap.  V.) 

§  23.  Neither  Grove  nor  Williams  has  considered  the 
hypothesis  of  an  interstellary  medium  in  its  geological 
relations.  Dr.  P.  Martin  Duncan,  however,  in  his  address 
as  President  of  the  Geological  Society  of  London,  in  May, 
1877,  without  noticing  the  priority  of  Grove,  has  adopted 


*  See  also  Williams  on  The  Radiometer  and  its  Lessons.    Quart.  Jour. 
Science,  October,  1876. 


-■'   Iff 


III.] 


RELATIONS   OF   THE   ATMO.SPHERE. 


43 


uu- 
Slat- 
lious 
(I  on 
t  the 
,g  to 
,f  the 
body 
Bgular 
attrac- 
ng  the 
Lug  the 
affords 
ents  in 
li  is  the 
thereby 

thence 
[l  ether, 

be,  in 
[ate,  and 
ies  to  be 

utrated 

,00.  cit., 


it  from  Williams,*  but  instead  of  supposing,  with  these, 
that  tlie  atmospheres  of  all  bodies  are  in  equilibrium,  con- 
ceives the  sun,  in  virtue  of  its  greater  mass,  to  be  slowly 
attracting  to  itself  the  earth's  terrestrial  envelope.  He 
then  proceeds  to  deduce  therefrom  important  geological 
considerations,  maintaining  that  from  the  greater  height 
of  the  terrestrial  atmosphere  which,  according  to  this 
view,  must  have  prevailed  in  former  ages,  there  would 
have  resulted  a  higher  temperature  at  the  earth's  surface, 
more  aqueous  vapor,  and  a  more  equable  cliunite.  From 
a  more  abundant  precipitation  wouiu  also  follow  greater 
sub-aerial  denudation,  while  the  formation  of  ice,  though 
it  might  occur  in  elevated  regions,  would  be  impossible  at 
or  near  the  sea-level. 

§  24.  The  correctness  of  all  these  deductions  by  Duncan 
from  the  condition  of  a  denser  terrestrial  atmosphere 
appears  to  be  indisputable,  and,  as  we  shall  endeavor  to 
show  in  the  sequel,  they  are  in  harmony  with  the  geologi- 
cal record.  But,  while  admitting  that  changes  in  the 
earth's  atmosphere  conducing  to  such  results  have  taken 
place,  we  maintain,  in  accordance  with  the  principles 
already  laid  down,  that  these  changes  have  not  been  due 
to  solar  attraction  and  absorption,  but  to  the  chemical  and 
mechanical  processes  going  on  at  the  surface  of  the  earth 
and  other  bodies  in  space,  whereby  the  atmospheric  ele- 
ments are  condensed  in  the  forms  of  liquid  and  solid 
water,  or  fixed  as  hydrates,  oxides,  carbonates  and  hydro- 
carbonaceous  matters. 

§  25.  The  changes  which  have  thus  been  produced  in 
tie  terrestrial  atmos[)here  are,  by  our  hypothesis,  reduced 
in  amount  by  being  shared  with  other  worlds,  and  the 
consequences  which  Ebelmen,  and  others  after  him,  have 

♦  It  is  due  to  my  friends,  Mr.  WilliaTHS  and  Dr,  Duncan,  to  say  tliat 
they  liave  both,  in  conversation,  informed  me  tliat  tliey  were  ignorant  of 
the  priority  of  Sir  William  Grove.  The  conception  appears  to  )"ave  been 
original  and  independent  in  tlie  mind  of  Mr.  Williums.  |Fcr  the  views 
of  Zcillner  as  to  the  interstellary  at?  .osphere,  see  below,  page  64.] 


I    ,! 


44 


THE  CHEMICAL  AND  GEOLOGICAL 


PII. 


V\ 


deduced  with  regard  to  tlie  temperature  of  the  earth's 
surface  in  former  geological  periods,  would  seem,  at  first 
sight,  to  be  invalidated.  Tyndall,  however,  in  18G1,  from 
a  consideration  of  the  great  power  of  absorbing  lieat  pos- 
sessed alike  by  aqueous  vapor  and  by  certain  gases,  such 
as  carbonic  dioxide,  and  the  consequent  effects  of  small 
quantities  of  these  in  the  atmosphere  on  terrestrial  radia- 
tion, and  thus  on  climate,  was  led  to  remark,  ''It  is  not 
therefore  necessary  to  assume  alterations  in  the  density 
and  height  of  the  atmosphere  to  account  for  different 
amounts  of  lieat  being  preserved  to  the  earth  in  different 
times;  a  slight  change  in  its  variable  constituents  may 
have  produced  all  the  mutations  of  climate  which  the 
researches  of  geologists  reveal."  *  Thus,  although  the 
amount  of  carbonic  dioxide  which  in  past  geological  ages 
has  been,  by  chemical  processes  at  the  surface  o^:  our  own 
and  other  worlds,  abstracted  from  the  universal  medium, 
may  not  have  sufficed  to  diminish  by  more  than  a  small 
fraction  the  barometric  pressure  at  the  earth's  surface, 
this  change  would  still  meet  all  the  requirements  of 
geological  history,  so  far  as  temperature  and  climate  are 
concerned.  From  this  point  of  view  the  suggestion  of 
Tyndall  assumes  a  weight  and  a  significance  not  hitherto 
suspected. 

§  26.  We  have  thus  briefly  endeavored  to  show  how 
the  hypothesis  of  a  universal  atmosphere  serves  to  explain 
certain  chemical  and  physical  facts  in  the  history  of  our 
globe.  To  discuss  it  in  all  its  bearings  would  require  a 
volume.  The  climatic  influences  of  a  denser  terrestrial 
atmosphere,  or  one  of  greater  absorptive  power  than  the 
present,  have  been  indicated  by  Ebelmen,  E.  B.  Hunt,  and 
Duncan,  and,  as  we  have  seen,  the  gradual  changes  in  the 
composition  of  the  atmosphere  imply  a  slow  progressive 
diminution  of  the  mean  annual  temperature  of  the  earth's 


♦  Tyndall,  Bakerian  Lecture  for  1861;  L.,  E.  &  D.  Phil.  Ma{;.,  Octo- 
ber, 1861,  and  Hunt,  Chem.  and  Geol.  Essays,  pp.  42  and  46.  i       *  • 


8t| 


llELATIONS  OF  THE  ATMOSPHEIIE. 


45 


surface.  This  concliisidii  is  in  contradiction  with  the 
hypothesis  of  secular  oscillations  of  the  oaitli's  tempera- 
ture, duo  to  astrononiical  causes,  and  giving  rise  to  suc- 
cessive po.iods  characterized  by  general  glaciaiion,  and 
leads  us  to  interrogate  on  this  point  the  geological  reco"d. 
We  may  iniiuire  (1)  whether,  since  the  appearance  of 
terrestrial  vegetation,  the  mean  annual  temperature  of  the 
earth  has  ever  been  less,  and  (2)  whether  it  has  ever  been 
greater  than  at  present.  It  is  clear  from  paleontological 
evidence  that  a  very  warm  climate  prevailed  over  the 
arctic  regions  during  the  Carboniferous,  Triassic,  Jurassic, 
and  Lower  Cretaceous  periods,  and  that  the  refrigeration 
apparent  in  the  Upper  Cretaceous  gradually  augmented 
up  to  the  Pliocene,  the  cold  of  which  has  continued  till 
now,  subject  to  certain  variations  in  its  distribution  which 
are  readily  accounted  for  by  changed  geographical  condi- 
tions. Such  changes  of  sea  and  land  are,  however,  inade- 
quate to  explain  the  elevated  temperature  which,  according 
to  the  observations  of  Nordenskiold,  prevailed  in  the  Car- 
boniferous age,  when  the  arctic  climate  permitted  the 
development,  over  a  great  area  of  land,  of  a  vegetation 
not  unlike  the  Carboniferous  flora  of  the  inter-tropical 
regions.  It  is  not  easy  to  conceive  that,  with  an  atmos- 
phere like  that  of  the  present  time,  any  geographical  con- 
ditions could  maintain  during  the  long  polar  winter  the 
mild  climate  required  for  such  a  vegetation,  even  in  insu- 
lar regions,  and  still  less  over  a  continental  area  within 
the  poHr  circle. 

§  27.  We  are  thus  led  to  the  conclusion  that  geographi- 
cal changes,  though  adequate  to  explain  the  greater 
refrigeration  of  certain  areas  since  the  beginning  of  Plio- 
cene time,  are  not  sufficient  to  account  for  the  warmer 
climates  of  previous  ages,  and  to  find  the  explanation  of 
these  in  the  different  relations  of  the  earlier  atmosphere 
alike  to  solar  and  to  terrestrial  heat.  It  is,  however,  ob- 
vious that,  with  such  an  atmosphere  as  we  have  supposed, 
the  more  elevated  portions  of  the  earth's  surface  might, 


46 


THE  CHEMICAL  AND  GEOLOGICAL 


[III. 


i  i 


I  k\ 


as  is  now  the  case  in  inter-tropical  lands,  be  lifted  into 
rej^ions  where  glaciation  was  possible,  while  a  warm  cli- 
mate prevailed  everywhere  at  the  sea-level.  Neither  the 
glacial  periods  of  more  recent  times,  nor  those  of  remoter 
geological  ages,  of  which  evidence  is  not  wanting,  neces- 
sarily depend  upon  any  diminution  in  the  earth's  mean 
annual  temperature  at  the  sea-level.  Glacial  periods  are, 
in  this  view,  as  has  been  well  said  by  J.  F.  Campbell,  not 
celestial,  but  local  and  terrestrial,*  while,  on  the  contrary, 
the  warmer  polar  climates  of  Paleozoic  and  Mesozoic 
times  are  to  be  regarded  as  evidence  of  a  generally  ele- 
vated temperature  at  the  earth's  surface  depending  on 
atmospheric  conditions,  as  already  set  forth. 

§  28.  In  a  note  in  the  Comptes  Rendus  of  the  French 
Academy  of  Sciences  for  October  7,  1878,  criticising  my 
previous  one  of  September  23,  "Sur  les  relations  gdolo- 
giques  de  I'atmosphbre,"  already  referred  to  at  the  begin- 
ning of  this  paper,  Mr.  Stanislas  Meunier  has  argued  in 
favor  of  the  terrestrial  origin  of  the  atmospheric  carbonic 
dioxide,  the  source  of  which  he  supposes  to  be  a  subterra- 
nean oxidation  of  a  primitive  store  of  carbon,  a  view 
that  seems  unsupported  by  any  facts  or  analogies  in 
nature.  He  opposes  to  the  hypothesis  which  I  have  advo- 
cated, the  fact  of  the  absence  of  an  atmosphere  from  the 
moon,  while  he  asserts  the  existence  of  an  abundant  one 
around  both  Mercury  and  Venus.  The  evidences  of  such 
an  atmosphere  around  the  latter  planet  are  well  known, 
but  the  observations  of  recent  astronomers  leave  it  doubt- 
ful, on  the  contrary,  whether  Mercury  possesses  a  percep- 
tible one,  while,  as  regards  our  satellite,  the  conclusion, 
as  stated  by  Newcomb,  is  that  the  lunar  atmosphere,  if  it 
exists,  is  not  equal  to  more  than  one  four-hundredth  that 
of  the  earth. 

§  29.  A  little  reflection  will,  however,  show  that  the 
absence  of  any  apparent  atmosphere  from  the  moon  in  no 

*  Campbell,  on  Glacial  Periods;  Quart.  Jour.  Geol.  Soc,  1879,  vol. 
XXXV.,  p.  t)8. 


...  ^^ 


II. 

to 
ili- 
,he 
ter 
5ea- 
ean 
are, 
not 
ary, 
zoic 
ele- 
y  on 

ench 

g  my 

T^olo- 


UI.] 


RELATIONS  OF  THE  ATMOSPHERE. 


47 


Ihat  tlie 

In  'w"'  no 

1879,  vol. 


way  militates  against  our  hypothesis,  since  a  completely 
refrigerated  globe,  such  as  our  satellite  riiust  probably  be, 
would  long  since  have  absorbed  mechanical]}'  into  its  inter- 
stices its  share  of  the  universal  gaseous  medium.  It  was 
many  years  since  pointed  out  by  Siemann  *  that,  as  a  con- 
sequence of  the  progressive  refrigeration  of  our  planet,  the 
ocean  and  the  air  which  surround  it  must  one  day  disap- 
pear from  its  surface.  The  total  volume  of  our  atmos- 
phere, at  the  density  which  it  has  at  the  sea-level,  is, 
according  to  his  calculation,  less  than  four  thousandths 
of  that  of  the  earth,  the  volume  of  the  ocean  being  very 
much  less.  There  is  no  known  mass  of  cooled  rock  which 
has  not  a  greater  oorosity  than  is  represented  by  these 
figures,  so  that  the  conclusion  seems  inevitable  that,  with 
the  complete  refrigeration  of  the  earth  which  must  come 
in  the  course  of  ages,  its  atmosphere,  following  the  ocean, 
will  have  so  completely  sunk  into  the  pores  of  the  cooled 
mass  that  its  tension  at  the  surface  would  be  very  small. 
Such  a  condition  of  things  Ssemann  supposes  to  have 
been  already  attained  in  our  satellite,  a  view  which  may 
be,  with  equal  probability,  extended  to  Mercury. 

§  30.  The  hypothesis  that  interstellary  space  is  filled 
with  an  attenuated  matter  which,  in  a  more  condensed 
form,  constitutes  the  atmosphere  and  the  waters  of  our 
own  and  other  worlds,  which  we  have  already  discussed 
in  some  of  its  chemical  and  geological  bearings,  assumes 
a  new  interest  in  connection  with  recent  speculations  as 
to  evolution  in  the  stellar  universe.  In  considering  the 
increasing  chemical  complexity  revealed  by  the  spectro- 
scope in  passing  from  nebulfe  to  white,  yellow,  and  red 
stars.  Prof.  F.  W.  Clarke,  of  Cincinnati,  was  led  in  1873  f 
to  suggest  the  possibility  of  a  generation  of  the  higher 
from  simpler  forms  of  matter  by  a  process  of  cosmical 

*  Snr  I'unit^  des  phenombnes  gdologiques  dans  le  syst&me  planetaire 
dusolell,  Bull.  Soc.  Geol.  de  Fr.,  1860-61,  vol.  xviii.,  p.  322,  translated  by 
the  present  writer  for  the  Amer.  Jour.  Science,  II.,  xxxili.,  p.  30. 

t  Popular  Science  Monthly,  Jan.,  1873,  vol.  ii.,  p.  32. 


iH:    .i 


J-Tfj  nt'mtv^'*,-*' 


48 


THE  CHEMICAL  AND   GEOLOGICAL 


■^'  I'ili  i'liii 


chemistry.  A  similar  view  was  a  few  months  later  ad- 
vanced by  Mr.  Lockyer,  who  reiterated  and  enforced  these 
suggestions,  showing  that  the  chemical  elements  make 
their  appearance  in  the  cooling  stars  in  the  order  of  their 
vapor-densities  —  and  mouover  connected  these  considera- 
tions with  the  conjectures  of  Dumas  as  to  the  probably 
compound  nature  of  the  so-called  elements.*  Mr.  Lock- 
yer has  since  extended  this  inquiry  by  his  ingenious  and 
beautiful  spectroscopic  studies,  the  results  of  which  are 
embodied  in  his  "  Discussion  of  the  "Working  Hypothesis 
that  the  so-called  Elements  are  Compound  Bodies,"  com- 
municated to  the  Royal  Society,  December  12,  ISYS.f  In 
his  first  note,  of  1873  (which  is  embodied  in  the  later 
puper),  he  suggested  that  we  see  in  the  stars  evidences  of 
a  celestial  dissociation  under  the  influence  of  intense  heat, 
which,  continuing  the  work  of  our  furnaces,  would  break 
up  the  metalloids,  and  leave  only  the  metallic  elements  of 
low  equivalent  weight  which  are  found  in  the  hottest 
stars.  In  his  later  memoir  he  further  suggests  that  as 
there  may  be  no  superior  limit  to  temperature,  so  of  disso- 
ciation there  may  be  no  end. 

§  31.  With  these  may  be  compared  the  views  enunci- 
ated by  the  present  writer  in  a  le:i/Ure  before  the  Royal 
Institution,  May  31.  1867,  wherein,  discussing  the  prob- 
lems of  stellar  chemistry,  he  declared  that  the  "dissocia- 
tion of  elements  by  intense  heat  is  a  principle  of  universal 
application,"  and  with  regard  to  the  chemical  elements, 
that  their  "further  dissociation  in  stellar  or  nebulous 
masses  may  give  us  evidence  of  matter  still  more  elemen- 
tal than  that  revealed  by  the  experiments  of  the  1  ibora- 
tory,  where  we  can  only  conjecture  the  compound  nature 
of  many  of  the  so-called  elementary  substances."  J     In 

»  Comptes  Rendus,  Nov.  3,  1873. 

t  Amer.  Jour.  Science,  III.,  xvil.,  93-116;  and  farther,  Clarke,  Science 
News,  Feb.  15,  1879,  p.  114. 

t  Rerrlnted  from  Proc.  Royal  Institution  in  Chem.  and  Geol.  Essays, 
p.  37. 


in. 

ad- 

ese 

ake 

iieir 

.era- 

ably 

,ock- 

and 
1  are 
thesis 

com- 
A    In 

later 
ices  oi 
e  heat, 
L  break 
lents  of 

hottest 

that  as 
of  disso- 

en^nci- 
Le  Royal 
the  pi'ob- 

dissocia- 
luniversal 
|(»lements, 

nebulous 
eleraeii- 

l^e  1  ibora- 

[nd  nature 

!s.n  ^^ 

[arke,  Science 
Geol.  Essays, 


m.] 


RELATIONS  OF  THE  ATMOSPHERE. 


49 


1874,  while  discussing  the  speculations  of  Dumas,  Clarke, 
and  Lockyer,  he  further  suggested  that  the  green  line  in 
the  spectrum  of  the  solar  corona,  which  had  been  sup- 
posed to  indicate  a  hitherto  unknown  element,  may  be  a 
"  more  elemental  form  of  matter,  which,  though  not  seen 
in  the  nebulae,  is  liberated  by  the  intense  heat  of  the  solar 
sphere,  and  may  possibly  correspond  to  the  primary  mat- 
ter conjectured  by  Dumas,  having  an  equivalent  weight 
one-fourth  that  of  hydrogen."  *  Regarding  this  supposed 
element  in  the  solar  atmosphere.  Prof.  C.  A.  Young 
remarks  that  it  must  be  of  excessive  tenuity,  "a  near 
relative,  so  far  as  gravity  is  concerned,  to  the  luminiferous 
ether,  and  to  the  Urstoff  of  the  German  speculators."  f 
In  this  connection  it  should  be  mentioned  that  Hinrichs, 
in  1»66,  put  forth  an  argument  J  in  favor  of  the  existence 
of  such  a  primitive  matter  or  Urstoff  from  a  consideration 
of  the  wave-lengths  in  the  spectra  of  the  various  ele- 
ments. § 

§  32.  Lavoisier  long  since  suggested  that  hydrogen, 
nitrogen,  and  oxygen  are,  with  heut  and  light,  the  simpler 
forms  of  matter  from  which  all  others  are  derived,  and 

*  A  Century's  Progress  in  Theoretical  Chemistry,  by  T.  S.  Hunt,  being 
an  address  delivered  on  the  Centennial  of  Chemistry,  at  Northumberland, 
Penn.,  July  31,  1874;  Amer.  Chemist,  vol.  v.,  pp.  4G-51,  and  Pop.  Science 
Monthly,  vii.,  420. 

t  Amer.  Jour.  Science,  11. ,  xlii.,  350-368. 

t  J'>ic^ni.,  i.,  319. 

S  since  these  pages  were  in  type  my  attention  has  been  called  to  a 
paper  read  before  the  Literary  and  Historical  Society  of  Quebec  in  Janu- 
ary, 1870,  by  James  Douglas,  Jr.,  then  President  of  the  Society,  and  one 
of  the  Canadian  expedition  to  observe  the  total  solar  eclipse  of  August  7, 
18Gi).  Therein,  while  discussing  the  spectroscopic  observations  made 
during  the  eclipse,  he  refers  to  those  of  Professor  Young,  who  had  sug- 
gested a  comparison  between  certain  lines  in  the  spectrum  of  the  solar 
corona  and  those  observed  by  Winlock  in  that  of  the  aurora  borealis. 
With  regard  to  these  lines,  Mr.  Douglas  then  adds,  "  May  they  not  there- 
fore belong  to  some  imknown  element ;  —  a  gas  lighter  than  hydrogen, 
which,  like  the  hypothetical  ether,  fills  space?"  To  this  he  adds  the 
suggestion  that  electricity,  both  "  in  the  auroral  light  of  our  own  heavens 
and  the  corona  of  the  sun,  may  render  this  hypothetical  gas  luminous." 
Trans.  Lit.  and  Hist.  Soc.  of  Quebec,  New  Series,  part  7,  p.  82. 


1  1 


P    ^'1    ^!il 


60 


CHEMISTRY  01'  'x.  "^.  ATMOSPHERE. 


[UI. 


when  it  is  considered  that  the  firsb  two  of  these  are  the 
only  elements  of  which  we  have  yet  any  certain  evidence 
in  the  nebulie,  it  will  be  seen  that  the  speculation  of 
Lavoisier  is  really  an  anticipation  of  that  view  to  which 
spectroscopic  stacly  has  led  the  chemists  of  to-day.  The 
three  elements  named  by  him  are  thoiie  which,  in  the 
forms  of  air  and  watery  vapor,  make  up  nine  hundred  and 
ninety-nine  thousandths  of  the  atmosphere  which,  in  ac- 
cordance with  our  hypothesis,  constitutes  the  interstellary 
medium.  It  was  in  view  of  all  these  considerations  that 
the  writer  in  1874  ventured  to  say  that  "the  nebulsB  and 
their  resultant  worlds  may  be  evolved  by  a  process  of 
chemical  condensation  from  this  universal  atmosphere ; 
to  which  they  would  sustain  a  relation  somewhat  analo- 
gous to  that  of  clouds  and  rain  to  tiie  aqueous  vapor 
around  us."*  Such  a  speculation,  which  seeks  for  a  source 
of  the  nebulous  matter  itself,  is  perhaps  a  legitimate  ex- 
tension of  the  nebular  hypothesis. 

*  A  Century's  Progress,  etc.,  cited  above;  also  Chem.  and  Geol. 
Essays,  preface  to  2d  ed.,  p.  six. 


H 


,„„ II!  j 


rv. 

CELESTIAL  CHEMISTRY  FROM  THE  TIME  OP  NEWTON. 

This  Essay,  read  before  the  Ph.'.i  ophical  Socletj  of  Cambridge,  England,  No- 
vember 28, 1881,  and  published  in  its  Proceedings  (Vol.  IV.,  part  iii.),  was  reprinted 
in  the  Chemical  N^ws,  and  also  in  the  Aniericau  Journal  of  Science  for  February, 
1882  ([111. J  xxxiii.,  123-133).  A  paper  on  "The  Conservation  of  Solar  Enerijy,"  by 
C.  W.  Siemens,  was  received  by  the  KoyaJ  Society  of  London,  February  20, 18H2,  and 
])ublished  in  its  Proceedings,  Number  21!»,  and  also  in  Nature,  vol.  xxv.,  p.  440.  Its 
author  therein  called  attention  to  my  recent  essay  wiiioh  had  made  known  to  him 
the  ideas  of  Newton,  and,  after  repeating  my  story  of  the  "  Hypothesis  touching  Light 
and  Color,"  adds,  "  And  now  once  more  a  philosopher  on  the  other  side  of  the  Atlan- 
tic brings  bacli  to  the  birthplace  of  Newton  his  forgotten  and  almost  despised  work 
of  two  hundred  years  ago."  Siemens  admitted,  with  Grove,  Williams,  and  myself, 
the  existence  of  attenuated  matter  in  space,  which  he  sui)pased  to  include  oxygen, 
nitrogen,  hydrogen,  aqueous  vapor,  and  carbon  compounds,  besides  solid  materials, 
probably  exhalations  from  the  sun  which  constitute  the  so-called  cosmic  dust.  In 
my  review  of  the  paper  of  Siemens  (Nature,  April  27,  1882  ;  vol.  xxv.,  p.  C13)  I  have 
called  attention  to  the  fact  that  already  in  a  communication  to  the  French  Academy 
of  Science,  September  23,  1878,  cited  below  (Comptes  Kcndus,  >'ol.  xxxviii.,  p.  452), 
on  the  subject  of  an  Interstellary  medium  as  afford; ut  ■>  means  of  material  commu- 
nication between  celestial  bo<lies,  I  suggested  a  simi,  .■  origin  of  cosmic  dust,  say- 
ing, "  Cette  theorie  d'une  ^change  univeraelle  nie  pa.  't  fournir  une  explication  de 
I'origine  des  poussiferes  cosmiques."  My  criticism  from  Nature  >vill  be  found  re- 
printed, with  much  other  literature  on  the  subject,  in  a  volume  by  Siemens,  in  1883, 
"On  the  Conservation  of  Solar  Energy." 

In  explanation  of  its  concluding  paragraph  it  should  be  said  that  the  author,  who 
had  sketched  the  outli.  of  the  present  essay  in  Italy,  some  weeks  before,  and  pro- 
posed to  complete  it  in  London,  was  unexpectedly  called  thence  to  Cambridge,  a  few 
days  before  the  time  which  had  been  assigned  for  its  presentation,  and  was  a  guest 
in  quarters  In  the  Master's  Court  of  Trinity  College,  where,  near  the  rooms  formerly 
occupied  by  Newton,  in  the  same  court,  he  was  obliged  to  finish  the  essay  which  had 
been  promised  to  the  Piiilosophical  Society. 


§  1.  The  late  W.  Vernon  Harcoiirt,  in  1845,*  called 
attention  to  the  remarkable  perception  of  great  chemical 
truths  which  is  apparent  in  the  Queries  appended  to  the 
third  book  of  Newton's  Optics,  as  well  as  in  his  Hypothe- 
sis touching  Light  and  Color.  With  regard  to  the  latter, 
Haicourt  then  remarked,  "It  has,  I  think,  scarcely  been 
quoted,  except  by  Dr.  Young,  and  its  existence  is  but 
little    known,   even  among  the  best-informed  scientific 

*  L.,  E.  and  D.  Phllos.  Magazine,  III,,  xxvili.,  106  and  478;  also 
xxix.,  185. 

61 


i 

If 

1 '    1 

* 

111 

T'l; 


f:' 


m  ■a 


ii'  ;iiiH 


■  I  >    m\> 


M^ 


'fill  I   Mlilllil 
11  I 


62 


CELESTIAL  CHEMISTRY 


PV. 


men."  The  essay  in  question  was  read  before  the  Royal 
Society,  December  9  and  16,  1675,  but  remained  un- 
published till  1757,  when  Birch,  at  that  time  secretary  to 
the  Society,  printed  it,  not  without  verbal  inaccuracies,  in 
the  third  volume  of  his  History  of  the  Royal  Society ;  a 
work  inkiided  to  serve  as  supplement  to  the  Philosophi- 
cal Transactions  up  to  that  date.  In  1846,  at  the  sugges- 
tion of  Harcourt,  the  Hypothesis  of  Newton  was  again 
printed  in  the  L.,  E.  and  D.  Philosophical  Magazine  (vol- 
ume xxix.),  and  it  subsequently  appeared  in  the  Appendix 
to  the  first  volume  of  Brewster's  Memoirs  of  Sir  Isaac 
Newton,  in  1855. 

The  time  has  come  for  further  inquiries  into  the  science 
of  Newton,  and  I  shall  endeavor  to  show  that  a  careful 
examination  of  the  writings  of  our  great  natural  philos- 
opher, in  the  light  of  the  scientific  progress  of  the  last 
generation,  renders  still  more  evident  the  wonderful  pre- 
vision of  him  who  already  two  centuries  since  had  anti- 
cipated most  of  the  recent  speculations  and  conclusions 
regarding  cosmic  chemistry. 

§  2.  As  an  introduction  to  the  inquiries  before  us,  and 
in  order  to  show  the  real  significance  of  the  speculations 
of  Newton,  it  will  be  necessary  to  review,  somewhat  at 
length,  the  history  of  certain  views,  enunciated  almost 
simultaneously  by  the  late  Sir  Benjamin  Brodie,  of  Ox- 
ford, and  the  present  writer,  and  subsequently  developed 
and  extended  by  the  latter.  In  part  I.  of  his  Calculus  of 
Chemical  Operations,  read  before  the  Royal  Society,  May 
3,  1866,  and  published  in  the  Philosophical  Transactions 
for  that  year,  Brodie  was  led  to  assume  the  existence  of 
certain  ideal  elements.  These,  he  said,  "  though  now  re- 
^vealed  to  us  through  the  numerical  properties  of  chemical 
equations  only  as  implicit  and  dependent  existences,  we 
cannot  but  surmise  may  sometimes  become,  or  may  in  the 
past  have  been,  isolated  and  independent  existences.'''' 
Shortly  after  this  publication,  in  the  spring  of  1867,  I 
spent  several  days  in  Paris  with  the  late  Henri  Sainte- 


IV.] 


FROM  THE  TIME  OF   NEWTON. 


58 


Claire  Deville,  repeating  with  him  some  of  his  remarka- 
ble experiments  in  chemical  dissociation,  the  theory  of 
which  we  then  discussed  in  its  relations  to  Faye's  solar 
hypothesis. 

§  3.  From  Paris,  in  the  month  of  May,  I  went,  as  the 
guest  of  Brodie,  for  a  few  days  to  Oxford,  where  I  read 
for  the  first  time,  and  discussed  with  him,  his  essay  on  the 
Calculus  of  Chemical  Operations,  in  which  connection 
occurred  the  very  natural  suggestion  that  his  ideal  ele-  ' 
ments  might  perhaps  be  liberated  in  solar  fires,  and  thus 
be  made  evident  to  the  spectroscope.  I  was  then  about 
to  give,  by  invitation,  a  lecture  before  the  Royal  Institu- 
tion in  London  on  the  Chemistry  of  the  Primeval  Earth, 
which  was  delivered  May  31,  1867.  A  stenographic  re- 
port of  the  lecture,  revised  by  the  author,  was  published 
in  the  Chemical  News  of  June  21,  1867,  and  in  the  Pro- 
ceedings of  the  Royal  Institution.*  Therein,  I  consid  -red 
the  chemistry  of  nebulae,  sun,  and  L'tars  in  the  combined 
light  of  (spectroscopic  analysis  and  Deville's  researches 
on  dissociation,  and  concluded  with  the  generalization 
that  the  "breaking-up  of  compounds,  or  dissociation  of 
elements,  by  intense  heat  is  a  principle  of  universal  appli- 
cation, so  that  we  may  suppose  that  all  the  elements  which 
make  up  the  sun,  or  our  planet,  would,  when  so  intensely 
heated  as  to  be  in  the  gaseous  condition  which  all  matter 
is  capable  of  assuming,  remain  uncombined;  that  is  to 
say,  would  exist  together  in  the  state  of  chemical  ele- 
ments ;  whose  further  dissociation  in  stellar  or  nebulous 
masses  may  even  give  us  evidence  of  matter  still  more 
elemental  than  that  revealed  in  the  experiments  of  the 
laboratory,  where  we  can  only  conjecture  the  compound 
nature  of  many  of  the  so-called  elementary  substances." 

§  4.  The  importance  of  this  conception,  in  view  of 
subsequent  discoveries  in  spectroscopy  and  in  stellar 
chemistry,  has  been  well  set  forth  by  Lockyer  in  his  late 


*  See  also  Hunt's  Chemical  and  Geological  Essays,  pp.  35-45. 


11 


tiL  I' 


54 


CELESTIAL  CHEMISTRY 


[IV. 


lectures  on  Solar  Phj^sics,*  where,  however,  the  general- 
ization is  described  as  having  been  first  made  by  Brodie 
in  1867.  A  similar  but  later  enunciation  of  the  same  idea 
by  r^erk-M '  we'l  is  also  cited  by  Lockyer.  Brodie,  in 
fact,  ;;  ti.:.  yth  Oi  June,  one  week  after  my  own  lecture, 
gave  i.  'ii.!Vi  >  on  Ideal  Chemistry  before  the  Chemical 
Society  >■  Lojdou,  published  in  the  Chemical  News  of 
June  14,  in  wIjs  ...  with  regard  to  his  ideal  elements,  in 
further  extension  of  the  suggestion  already  put  forth  by 
him  in  the  extract  above  given  from  his  paper  of  May  6, 
1866,  he  says,  "We  may  conceive  that  in  remote  ages  the 
temperature  of  matter  was  much  higher  than  it  is  now, 
and  that  these  other  things  [the  ideal  elements]  existed 
in  the  state  of  perfect  gases  —  separate  existences  —  un- 
combined."  He  further  suggested,  from  spectroscopic 
evidence,  that  it  is  probable  that  "  we  may  one  day,  from 
this  source,  have  revealed  to  us  independent  evidence 
of  the  existence  of  these  ideal  elements  in  the  sun  and 
stars." 

During  the  months  of  June  and  July,  1867,  I  was 
absent  on  the  continent,  and  this  lecture  of  Brodie's 
remained  wholly  unknown  to  me  until  its  republication 
in  1880,  in  a  separate  form,  by  its  author,f  with  a  preface, 
in  which  he  pointed  out  that  he  had  therein  suggested 
the  probable  liberation  of  his  ideal  elements  in  the  sun, 
referring  at  the  same  time  to  his  paper  of  1866,  from 
which  we  have  already  quoted  the  only  expression  bear- 
ing on  the  possible  independence  of  these  ideal  elements 
somewhere  in  time  or  in  space. 

§  5.  The  above  statements  are  necessary  in  order  to 
explain  why  it  is  that  I  have  made  no  reference  to  Sir 
Benjamin  Brodie  on  the  several  occasions  on  which,  in 
the  interval  between  1867  and  the  present  time,  I  have 
reiterated  and  enforced  my  views  on  the  great  significance 
of  the  hypothesis  of  celestial  dissociation  as  giving  rise  to 

*  Nature,  August  25,  1881,  vol.  xxiv.,  p.  396. 
t  Ideal  Chemistry,  a  Lecture.    Macmillan,  1880. 


IV.] 


FROM   THE  TIME  OF   NEWTON. 


66 


forms  of  matter  more  elemental  than  any  known  to  us  in 
terrestrial  chemistry.  The  conception,  as  at  first  enun- 
ciated in  somewhat  different  forms  alike  by  Brodie  and 
myself,  was  one  to  which  we  were  both  naturally,  one 
might  say  inevitably,  led  by  different  paths  from  our 
respective  fields  of  speculation,  and  which  each  might 
accept  as  in  the  highest  degree  probable,  and  make,  as  it 
were,  his  own.  I  write,  therefore,  in  no  spirit  of  invidious 
rivalry  with  my  honored  and  lamented  friend  ,it  ">'mply 
to  clear  myself  from  the  charge,  which  miglit  ot-  rwise 
be  brought  against  me,  of  having  on  vari^  ^  oc  a.nons 
within  the  past  fourteen  years  put  forth  d  enlarged 
upon  this  conception  without  mentioning  Sii  Benjamin 
Brodie,  whose  only  publication  on  the  subi  -^t,  so  far  as  I 
am  aware,  was  his  lecture  of  1867,  unkno\s  i  >  me  until 
its  reprint  in  1880. 

§  6.  It  was  at  the  grave  of  Priestley,  in  1874,  that  I 
for  the  second  time  considered  the  doctrine  of  celestial 
dissociation,  commencing  with  an  account  of  the  hy- 
pothesis put  forward  by  F.  W.  Clarke,  of  Cincinnati,  in 
January,  1873,*  to  explain  the  growing  complexity  which 
is  observed  when  we  compare  the  spectra  of  the  white, 
yellow,  and  red  stars  ;  in  which  he  saw  evidence  of  a  pro- 
gressive evolution  of  chemical  species,  by  a  stoichiogenic 
process,  from  more  elemental  forms  of  matter.  I  next 
referred  to  the  further  development  of  this  view  by 
Lockyer  in  his  communication  to  the  French  Academy 
of  Sciences  in  November  of  the  same  year,  wherein  he 
connected  the  successive  appearance  in  celestial  bodies  of 
chemical  species  of  higher  and  higher  vapor-densities  with 
the  speculations  of  Dumas  and  Pettenkofer  as  to  the  com- 
posite nature  of  the  chemical  elements.f  I  then  quoted 
from  my  lecture  ©f  1867  the  language  already  cited,  to 
the  effect  that   dissociation   by  intense   heat   in   stellar 


*  Clarke  [now  of  Washington,  D.  C],  on  "  Evolution  and  the  Spectros- 
cope," Popular  Science  Monthly,  New  York,  vol.  ii.,  p.  32. 
t  Lockyer,  Coniptes  Kenilus,  Xovembcr  3,  1873. 


■#■: 


I 


56 


CELESTIAL  CHEMISTRY 


i  ii- 
ll{ 

j 

: 

i 

; 

n 

,/\              ■; 

t  CI    I 


[E?* 


worldi?  might  give  us  more  elemental  forms  of  matter  than 
any  known  on  earth,  and  further  suggested  that  the  green 
line  in  the  spectrum  of  the  solar  corona,  which  had  been 
supposed  to  indicate  a  hitherto  unknown  substance,  may 
be  due  to  a  "  more  elemental  form  of  matter,  which, 
thougli  not  seen  in  the  nebulte,  is  liberated  by  the  intense 
heat  of  the  solar  sphere,  and  may  possibly  correspond  to 
the  priniary  matter  conjectured  by  Dumas,  having  an 
equivalent  weight  one-fourth  that  of  hydrogen." 

§  7.  The  suggestion  of  Lavoisier,  that  "  hydrogen, 
nitrogen,  and  oxygen,  with  heat  and  light,  might  be  re- 
garded as  simpler  forms  of  matter,  from  which  all  others 
are  derived,"  was  also  noticed  in  connection  with  the  fact 
that  the  nebuloe,  which  we  conceive  to  be  condensing  into 
suns  and  planets,  have  hitherto  shown  evidences  only  of 
the  presence  of  the  first  two  of  these  elements,  which, 
as  is  well  known,  make  up  a  large  part  of  the  gaseous 
envelope  of  our  planet,  in  the  forms  of  air  and  aqueous 
vapor.  With  this,  I  connected  the  hyj)othesis  that  our 
atmosphere  and  ocean  are  but  portions  of  the  universal 
medium  which,  in  an  attenuated  form,  fills  the  intcrstel- 
lary  spaces;  and  further  suggested,  as  "a  legitimate  and 
plausible  speculation,"  that  "  these  same  nebulaj  and  their 
resulting  worlds  may  be  evolved  by  a  process  of  chemical 
condensation  from  this  universal  atmosphere,  to  which 
they  would  sustain  a  relation  somewhat  analogous  to  that 
of  clouds  and  rain  to  the  aqueous  vapor  around  us."  * 

§  8.  Tliese  views  were  reiterated  in  the  preface  to  a  sec- 
ond edition  of  my  Chemical  and  Geological  Essays,  in  1878, 
and  again  before  the  British  Association  for  the  Advance- 
ment of  Science  at  Dublin,!  '^^^^  before  the  French  Acad- 
emy of  Sciences  in  the  same  year.|   They  were  still  fur.^her 

*  A  Century's  Progress  in  Theoretical  Chemistry,  being  an  address  at 
the  grave  of  Priestley  in  Northumberland,  Penn.,  July  31,  1874;  Amer. 
Chemist,  vol.  v.,  pp.  46-61   and  Pop.  S^ence  Monthly,  vi.,  p.  420. 

t  Nature,  August  29,  1878,  vol.  xviii.,  p.  475. 

J  Comptes  Rendus,  September  23,  1873,  vol.  xxxviii.,  p.  452.  ' 


iv.i 


FROM   TH.'i:  TIME   OF   NEWTON. 


6T 


developed  in  an  essay  on  the  Chemiciil  and  Geological 
Relations  of  the  Atmosphere,  published  in  May,  1880  (^ante 
pages  30-50),  in  .ich  attention  was  called  to  the  impor- 
tant contribution  to  the  subject  by  Mr.  Lockyer  in  his  in- 
genious and  beautiful  spectroscopic  studies,  the  results  of 
which  are  embodied  in  his  "  Discussion  of  the  W(jrking 
Hypothesis  that  the  so-called  Elements  are  Compound 
Bodies,"  communicated  to  the  Royal  Society,  December 
12,  1878.  It  was  then  remarked  that  the  already  noticed 
"speculation  of  Lavoisier  is  really  an  anticipation  of  that 
view  to  which  spectroscopic  study  lias  led  the  chemists  of 
to-diiy  " ;  while  it  was  said  that  the  hypothesis  put  forth 
by  the  writer  in  1874,  "which  seeks  for  a  source  of  the 
nebulous  matter  itself,  is  perhaps  a  legitimate  extension  of 
the  nebular  hypothesis." 

§  9.  To  show  the  connection  of  the  above  views  with 
the  philosophy  of  Newton,  it  now  becomes  necessary  to 
give  some  account  of  the  conception  of  the  universal  dis- 
tribution of  matter  throughout  space,  both  as  regards  its 
dynamical  relations  and  its  chemical  composition.  Pass- 
ing over  the  speculations  of  the  Greek  physiologists,  we 
conje  to  the  controversies  on  this  subject  in  the  seven- 
teenth century,  and  find,  in  apparent  opposition  to  the 
plenum  maintained  by  Descartes  and  his  followers,  the 
teaching  of  Newton  that  "the  heavens  are  void  of  all 
sensible  matter."  This  statement  is,  however,  qualified 
elsewhere  by  his  assertion,  that  "to  make  way  for  the  reg- 
ular and  lasting  movements  of  the  planets  and  comets,  it 
is  necessary  to  empty  the  lieavens  of  all  .natter,  except 
perhaps  some  very  thin  vapors,  steams,  and  effluvia,  arising 
from  the  atmospheres  of  the  earth,  planets,  and  comets, 
and  from  such  an  exceedingly  rare  ethereal  medium  as 
we  have  elsewhere  described,"  etc.  (^Opties^  Book  III. 
Query  28.) 

§  10.  In  order  to  understand  fully  the  views  of  Newton 
on  this  subject,  it  is  necessary  to  compare  carefully  his 
various  utterances,  including  the  Hypothesis,  in  1675,  the 


58 


CELESTIAL  CHEMISTRY 


UV. 


first  edition  of  the  Princlpia^  i»i  1087,  the  second  edition, 
in  1713,  and  tlio  various  editions  of  tlie  Optics.  This 
work  iip[)eured  in  1704,  tjje  tliird  book,  with  its  appended 
queries,  having,  according  to  its  autlior's  i)reface,  been 
"put  together  out  of  scattered  papers,"  subse([uent  to  the 
publicati(ni  of  the  first  edition  of  tlie  Principia.  Tiie 
Latin  transhition  of  iha  Optics,  by  Dr.  Clarke,  which  was 
published  in  1706,  and  the  second  English  edition,  in 
1718,  contiiin  successive  additions  to  these  queries,  which 
are  indicated  in  the  notes  to  Ilorsley's  edition  of  the 
works  of  Newton,  and  are  important  in  this  connection. 
From  a  collation  of  all  these,  we  learn  how  the  concep- 
tions of  the  Hypothesis  took  shape,  were  reinforced,  and 
in  great  part  incorporated  in  the  Principia. 

§  11.  In  the  Hypothesis,  he  ir^agines  "an  ethereal  me- 
dium much  of  the  same  constitution  with  air,  but  far 
rarer,  subtler,  and  more  elastic."  "But  it  is  not  to  be 
supposed  that  this  medium  is  one  uniform  matter,  but 
composed  partly  of  the  main  phl3gmatic  body  of  ether, 
partly  of  other  various  ethereal  spirits,  much  after  the 
manner  that  air  is  compounded  of  the  phlegmatic  body 
ot  air  intermixed  with  various  vapors  and  exhalations." 
Newton  further  suggests  in  his  Hypothesis  that  this  com- 
plex L-pirit  or  ether,  which,  by  its  elasticity,  is  extended 
throughout  all  space,  is  in  continual  movement  and  inter- 
change. "  For  nature  is  a  perpetual  circulatory  worker, 
generating  fluids  out  of  solids,  and  solids  out  of  fluids, 
fixed  things  out  of  volatile,  and  volatile  out  of  fixed,  sub- 
tile out  of  gross,  and  gross  out  of  subtile ;  some  things  to 
ascend  and  make  the  upper  terrestrial  juices,  rivers,  and 
the  atmosphere,  and  by  consequence  others  to  descend  for 
a  requital  to  the  former.  And  as  the  earth,  so  perhaps 
may  the  sun  imbibe  this  spirit  copiously,  to  conserve  his 
shining,  and  keep  the  planets  from  receding  farther  from 
him ;  and  they  that  will  may  also  suppose  that  this  spirit 
affords  or  carries  with  it  thither  the  solary  fuel  and  mate- 
rial principle  of  life,  and  that  the  vast  ethereal  spaces  be- 


nil  i  Ijji 


iv.i 


FROM  THE  TIME  OP  NEWTON. 


69 


tween  us  and  the  stars  are  for  a  suflicient  rcpositor^  for 
this  food  of  the  sun  and  phinets." 

§  12.  The  hiiiguage  of  tliis  hist  sentence,  in  whicli  his 
Lite  biographer,  Sir  David  lirewster,  regards  Newt(jn  as 
''amusing  himself  with  the  extravagance  of  his  s[)ecuhi- 
tions,"  at  which  "we  may  bo  aUowed  to  smile,"  *  was  not 
apparently  regarded  as  unreasonable  by  its  author  when, 
more  than  ten  years  1  ter,  ho  quoted  it  in  the  poststi-ipt 
of  his  letter  to  Ilalley,  dated  Cambridge,  Juno  20,  1080. 
The  views  therein  contained,  with  the  single  exception  of 
the  suggestion  regarding  gravitation,  have  not  wanted  ad- 
vocates in  our  own  time,  and  many  of  them  were  endjodied 
in  the  Principia,  which  Newton  was  then  engaged  in 
writing. 

§  13.  But  this  was  not  all :  Newton  saw  in  the  cosmic 
circulation  and  the  mutual  convertibility  of  rare  and 
dense  forms  of  matter  a  universal  law,  and  rising  to  a  still 
bolder  conception,  wiiieh  completes  his  Hypothesis  of  the 
Universe,  adds :  "  Perhaps  the  whole  frame  of  nature  may 
be  nothing  but  various  contextures  of  some  certain  ethe- 
real spirits  or  vapors,  condensed,  as  it  were,  by  precipita- 
tion, much  after  the  same  manner  that  vapors  are  con- 
densed into  water,  or  exhalations  into  grosser  substances, 
though  not  so  easily  condensible  ;  and  after  condensation 
wrought  into  various  forms,  at  first  by  the  immediate 
hand  of  the  Creator,  and  ever  since  by  the  power  of  na- 
ture, which,  by  virtue  of  the  command  'increase  and  mul- 
tiply,' became  a  complete  imitator  of  the  copy  set  lier  by 
the  g-  'at  Protoplast.  Thus,  perhaps,  may  all  things  be 
originated  from  ether." 

§  14.  If  now  we  look  to  the  third  book  of  the  Prin- 
cipia,  we  shall  find  in  Proposition  41  the  remarkable 
chemical  argument  by  which  Newton  was  led  to  reg.ird 
the  interstellary  ether  as  affording  "the  material  principle 
of  life"  iuid  "the  food  of  planets."  Considering  the  ex- 
halations from  the  tails  ot  comets,  he  supposes  thai:  the 
*  Brewster's  Memoirs  of  Newton,  vol.  i.,  pp.  121  and  404. 


Ill 
iiili 


\v\   M 


jiBmSSmOam 


60 


CELESTIAL  CHEMISTRY 


ipr. 


vapors  thus  derived,  being  rarefied,  dilated,  and  spread 
through  the  whole  heavens,  are  by  gravity  brought  within 
the  atmospheres  of  the  planets,  where  they  serve  for  tlie 
support  of  vegetable  life.  Inasmuch,  moreover,  as  all  veg- 
etation is  supported  by  fluids,  and  subsequently,  by  decay, 
is,  in  part,  changed  into  solids,  by  which  the  mass  of  the 
earth  is  augmented,  he  concludes,  that  if  these  essential 
matters  were  not  supplied  from  some  external  source,  they 
must  continually  decrease,  and  at  last  fail.  This  vital 
and  subtile  part  of  our  atmosphere,  so  important,  though 
small  in  amount,  might,  he  then  supposed,  come  from  the 
tails  of  comets.* 

§  15.  This  appeared  in  the  first  edition  of  the  Prineipia, 
in  1687.  It  was  not  until  later  that  the  conception  of 
exhalations  from  other  celestial  bodies  took  shape  in  the 
mind  of  Newton,  as  we  may  learn  from  the  Optics.  Thus, 
in  the  first  edition  of  this  work,  in  Query  11,  the  sun  and 
fixed  stars  are  spoken  of  as  great  earths,  intensely  heated, 
and  surrounded  with  dense  atmospheres  which,  by  their 

*  "  Vapor  enim  in  spatiis  illis  lib  idrais  perpetub  rarescit  ac  dilatatur. 
Qua  ratione  fit  ut  cauda  omnis  ad  extremitatem  superiorem  latior  sit 
quam  juxta  capita  cometae.  Ea  autem  rarefactione  vaporem  perpetu6 
dilatatura  diif undi  tandera  et  spargi  per  coelos  imiversos,  deinde  paulatim 
in  planetas  per  gravitatem  suani  attrahi  et  cum  eorum  atmospliaeris  rais- 
ceri,  ration!  consentaneum  videtur.  Nam  quemadmodum  maria  ad  con- 
stitutionem  Terrae  liujus  omnino  requiruntur,  idque  ut  ex  iis  per  calorem 
Solid  vapores  copiose  satis  excitentur,  qui  vel  in  nubes  coacti  decidant  in 
plu\  iis,  et  Terram  omnera  ad  procreationem  vegetabilium  irrigeut  et 
nutriant;  vel  in  frigidis  montium  verticibus  condensati  (ut  aliqui  cum 
ratione  phi'osophantur)  decurrant  in  fontes  et  flumina:  sic  ad  eonserva- 
tionem  marium  et  humorum  in  planetis  requiri  videntur  cometaj,  ex  quo- 
iTira  exhalationibus  et  vaporibus  condensatis,  quicquid  liquoris  per  vege- 
tationem  et  pntrefactionera  consumitur  et  in  Terram  aridam  convertitur, 
continu5  suppleri  et  refici  possit.  Nam  vegetabilia  omnia  ex  liquoribus 
omnino  crescunt,  dein  magnii  ex  parte  in  Terram  aridam  per  putrefac- 
tionem  abeunt,  et  limus  ex  liquoribus  putrefactis  perpetuo  decidit.  Hinc 
moles  Terrae  aridae  in  dies  augetur.  e'  uores,  nisi  aliunde  augmentum 
sumerent,  perpetuo  decrescere  deberem,,  ac  tandem  deficere.  Porro  sus- 
picor  spiritum  ilium,  qui  ai-ris  nostri  pars  minima  est,  sed  subtillissima 
et  optima,  et  ad  rernm  omnium  vitam  requiritur,  ex  cometis  praecipue 
venire."— iVeio ten,  rrincipia,  lib.  ill.,  prop.  xli. 


I     I 


rv.] 


FROM  THE  TIME  OF  NEWTON. 


61 


weight,  condense  the  exhalations  arising  from  these  hot 
bodies.  To  this  Query  is  added,  in  1706,  the  suggestion 
that  the  weight  of  such  an  atmosphere  "  may  hinder  the 
globe  of  the  sun  from  being  diminislied  except  by  the 
emission  of  light " ;  while  in  the  second  English  edition, 
in  1718,  we  find  a  further  addition  in  the  words,  "  and  a 
very  small  quantity  of  vapors  and  exhalations."  A  simi- 
lar change  of  view  appears  in  the  Query  now  numbered 
28,  wherein  we  read  of  "places  [almost]  destitute  of 
matter,"  and  also  that  "  the  sun  and  planets  gravitate 
towards  each  other  without  [dense]  matter  between." 
In  these  quotations  the  two  words  in  brackets  are  wanting 
in  the  edition  of  1706,  and  first  appear  in  that  of  1718 ; 
while  the  language  which  we  have  in  a  previous  page 
quoted  from  •  this  same  Query,  is  found  in  the  edition  of 
1706. 

§  16.  The  Queries  now  numbered  17-24,  appeared  for 
the  first  time  in  the  edition  of  1718,  and  herein  we  find, 
in  18,  the  ethereal  medium  spoken  of  as  being  "by  its  elas- 
tic force  expanded  through  all  the  heavens.".  Of  this 
medium,  "which  fills  all  space  adequately,"  he  asks,  "may 
not  its  resistance  be  so  small  as  to  be  inconsiderable,"  and 
scarcely  to  make  any  sensible  alteration  in  the  movements 
of  the  planets?*  This  complex  ether  of  the  interstellary 
space  wab  thus,  in  the  opinion  of  Newton,  made  up  in  part 
of  matter  common  to  the  planetar}^  and  stellar  atmos- 
pheres, the  origin  and  importance  of  which  is  concisely 
stated  in  the  paragraph  which  appears  for  the  first  time 
in  1713,  in  the  second  edition  of  the  Principia,  in  the  third 
book,  at  the  end  of  Proposition  42,  here  much  augmented. 
In  this  statement,  which  serves  to  supplement  and  com- 
plete that  already  made  in  1687,  in  Proposition  41,  we 
read  that  the  vapors  which  arise  alike  from  the  sun,  the 
fixed  stars,  and  the  tails  of  comets,  may  by  gravity  fall 
into  the  atmospheres  of  the  planets,  and  there  be  con- 
densed, and  pass  into  the  form  of  salts,  sulphurs  (^id  est, 
*  Compare  this  with  Prop,  x.,  Book  III.,  of  the  Principia. 


I' 


CELESTIAL  CHEMISTRY 


[IV. 


combustible  matters),  tinctures,  clay,  sand,  coral,  and 
other  terrestrial  substances.* 

§  17.  The  conception  of  Newton,  who,  while  rejecting 
alike  the  plenum  of  the  Cartesians,  with  its  vortices,  and 
an  absolute  vacuum,  imagined  space  to  be  filled  with  an 
exceedingly  attenuated  matter,  through  which  a  free  cir- 
culation of  gaseous  substances  might  take  place  between 
distant  worlds,  has  found  favor  among  modern  thinkers, 
who  seem  to  have  been  ignorant  of  his  views.  Sir  Wil- 
liam Grove  in  18-12  suggested  that  the  medium  of  light 
and  heat  may  be  "a  universjilly  diffused  matter,"  and  sub- 
sequently, in  1843,  in  the  chapter  on  Light,  in  his  "Es- 
say on  the  Corrc'ution  of  Physical  Forces,"  concluded 
with  regard  to  the  atmospheres  o!  the  sun  and  the  planets, 
that  then  is  no  reason  "why  these  atmosplieres  should 
not  be,  wiih  reference  to  each  other,  in  i  state  of  equilib- 
rium. Ether,  which  term  we  may  apply  to  the  highly 
attenuated  matter  existing  in  the  interplanetary  spaces, 
being  an  expansion  of  some  or  all  of  these  atmospheres,  or 
of  the  more  volatile  portions  of  them,  would  thus  furnish 
matter  for  the  transmission  of  the  modes  of  motion  which 
we  call  light,  heat,  etc. ;  and  possibly  minute  portions  of 
the  atmospheres  may,  by  gradual  accretions  and  subtrac- 
tions, pass  from  planet  to  planet,  forming  a  link  of  mate- 
rial communication  between  the  distant  monads  of  the 
universe."  Subseqaently,  in  his  address  as  Pi-esident  of 
the  British  Association  for  the  Advancement  of  Science, 
in  1866,  Grove  further  suggested  that  this  diffused  matter 
may  become  a  source  of  solar  heat,  "  inasmuch  as  the  sun 
may  condense  gaseous  matter  as  it  travels  in  space,  and 
so  heat  may  be  produced." 

§  18.    Humboldt,  also,  in  his  Cosmos,  considers  the  ex- 

*  "  Vapores,autem,  qui  ex  Sole  et  stellis  fixls  et  caudls  eometarum 
oriuntur,  incidere  possunt  per  gravitatom  siiam  in  atinospliaeras  planeta- 
ruin,  et  ibi  coiulensari  et  couverti  in  aquam  et  spiritos  luuniilos,  et 
siiliinde  per  lentiun  calorcm  in  sales,  et  sulphura,  et  t.nt'turas,  et  liniiun, 
et  Intiun,  et  argillani,  et  arenaui,  et  lapiiles,  et  coralla,  et  substantias  alias 
terrestres  paulatini  inigrare." — Newton,  Principia,  lib.  iii.,  prop.  xlil. 


IV.] 


FROM  THE  TIME  OP  NEWTON. 


63 


istence  of  a  resisting  medium  in  space,  and  says  "  of  tliis 
impeding  ethereal  and  cosmical  matter,"  it  may  be  sup- 
posed that  it  is  in  motion,  that  it  gravitates,  notwith- 
standing its  great  tenuity,  that  it  is  condensed  in  the 
vicinity  of  the  great  mass  of  the  sun,  and  that  it  may 
include  exhalations  from  comets ;  in  which  connection 
he  quotes  from  the  42d  Proposition  of  the  third  book  of 
of  the  Prlncipia.  He  further  speaks  comprehensively  of 
"the  vaporous  matter  of  the  incommensurable  regions 
of  space,  whether,  scattered  without  definite  limits,  it 
exists  as  a  cosmijal  ether,  or  is  condensed  in  nebulous 
masses  and  becomes  comprised  among  the  agglomerated 
bodies  of  the  universe."  *  Humboldt  also  cites  in  this 
connection  a  suggestion  made  by  Arago  in  the  Annuaire 
du  Bureau  des  Longitudes  for  1842,  as  to  the  possibility 
of  determining,  by  a  comparison  of  its  refractive  power 
with  that  of  terrestrial  gases,  the  density  of  "  the  ex- 
trer.  ely  rare  matter  occupying  the  regions  of  s^mce."  f 

§  19.  In  1854,  Sir  William  Thomson  published  his 
note  on  the  Possible  Density  of  the  Luminiferous  Ether,J 
wherein  he  remarks,  "that  there  must  be  a  medium  of 
material  communication  throughout  space  to  the  remotest 
visible  body,  is  a  fundamental  conception  of  the  undu- 
latory  theory  of  light.  Whether  or  no  this  medium  is 
(as  appears  to  me  most  probable)  a  continuation  of  our 
own  atmosphere,  its  existence  cannot  be  questioned." 
He  then  attempts  to  fix  an  inferior  limit  to  the  density  of 
the  luminiferous  medium  in  interplanetary  s})ace,  by  con- 
sidering the  mechanical  value  of  sunlight,  as  deduced 
from  the  value  of  solar  radiation  and  the  mechanical 
equivalent  of  the  thermal  unit.  He  concludes  "  that  the 
luminiferous  medium  is  enorijously  denser  than  the  con- 
tinuation of  the  terrestrial  atmosphere  would  be  in  inter- 


*  Cosmos,  Otte's  translation,  Harper's  ed.,  vol.  1.,  pp.  82,  86. 
t  Ibid.,  vol,  lii.,  p.  40. 

t  Trans.  Koy.  boc,  Edinburgh,  vol.  xxi.,  part  1 ;  and  Phil.  Mag^,  1855, 
vol.  ix.,  p.  36. 


'"'"'™- '■"■"" 


64 


CELESTIAL  CHEMISTRY 


[IV. 


' 


I    '  1 1 


'''11 


i      i 


^1  liHI 


planetary  space  if  rarefied  according  to  Boyle's  law 
always,  and  if  the  earth  were  at  rest  in  a  state  of  con- 
stant temperature,  with  an  atmosphere  of  the  actual 
density  at  its  surface."  The  earth  itself  in  moving 
through  space  "cannot  displace  less  than  250  pounds  of 
matter."  [  P.  Glan,  who  has  since  examined  the  ques- 
tion, concludes  that  the  lower  limit  of  density  would  be 
more  than  7000  times  greater  than  that  calculated  by 
Thomson.*] 

§  20.  In  1870,  W.  Mattieu  Williams  published  his  very 
ingenious  work  entitled  "The  Fuel  of  the  Sun,"  in  which, 
apparently  without  any  knowledge  of  what  had  been 
written  before  with  regard  to  an  interstellary  medium,  he 
attempts  to  find  tlierein  the  source  of  solar  heat — -the 
"solary  fuel"  of  Newton.  To  quote  his  own  huiguage, 
"the  gaseous  ocean  in  which  we  are  iunnersed  is  but  a 
portion  of  the  infinite  atmosphere  that  fills  the  whole 
solidity  of  space,  that  links  together  all  the  elements 
of  the  universe,  and  diffuses  among  them  light  and 
heat,  and  all  the  other  physical  and  vital  forci::s  which 
heat  and  light  are  capable  of  generating."  (Loc.  cit.  p.  5.) 

§  21.  [In  1872,  ap]  t,j;  d  the  remarkable  work  of  Zoll- 
ner,  '■'•Uber  .nc  Natuy  n.rr  i  mieten^''  in  which  tlie  view  of 
an  interstellary  atmospnere  is  set  forth  with  great  clear- 
ness. His  conclusions  may  be  gathered  from  the  follow- 
ing extracts  from  an  extended  review  and  analysis  of  the 
volume,  published  in  the  same  year.  Reasoning  from 
known  facts  it  is  maintained  that  even  such  fixed  bodies 
as  the  metals,  at  very  low  temperatures,  are  constantly  giv- 
ing off  vapor,  though  in  amount  too  small  to  be  recognized 
by  ordinary  tests;  whence  "it  follows  that  a  mass  of  mat- 
ter in  space  will  ultimately  surround  itself  with  its  own 
vapor,  and  the  tension  of  the  latter  will  depend  upon  the 
mass  of  the  body  —  that  is,  upon  its  gravitative  energy  — 


*  Ann!»i.;n  der  Physifc  unci  Chemie,  No.  vlii.,  1870;  cited  by  the  author 
in  a  revitnv  of  Siemens,  in  "  Nature  "  for  April  27, 1882  ;  nlso  in  "  Conser- 
vation of  Solar  Energy,"  by  yiemena,  1883,  p.  33. 


IV.] 


FROM  THE  TIME  OF   NEWTON. 


65 


iw 
)n- 
iial 
ing 

Lies- 
.  be 
,  by 

very 
hich, 
been 
m,  lie 
—  the 
i-uage, 
but  a 
whole 
jments 
it   and 
which 
p.  5.-) 
f  ZoU- 
iew  of 
It  cleav- 
follow- 
of  the 
from 
bodies 

itly  giv- 
oo-nized 

of  mat- 
its  own 
Jipon  the 

bergy  — 

Ithe  author 
"  Conser- 


Irv 


and  the  temperature.  If  the  mass  of  the  body  is  so  small 
that  its  attractive  force  is  insuthcient  to  give  to  the  en- 
veloping vapor  its  maximum  tension  for  the  existing  tem- 
perature, the  evolution  of  vapor  will  be  continuous,  until 
the  whole  mass  is  converted  into  it." 

§  22.  ["  Then  comes  the  question  whether  a  mass  of  gas 
or  vapor  under  these  circumstances  would  be  in  a  state  of 
stable  equilibrium.  The  analytical  discussion  of  this  point 
leads  to  the  result  that  in  empty  and  unlimited  space, 
a  finite  mass  of  gas  is  in  a  condition  of  unstable  equilib- 
rium and  must  become  dissipated  by  continual  expansion 
and  consequent  decrease  of  density.  A  necessary  conse- 
quence of  this  result  is  that  tlie  celestial  spaces,  at  least 
within  the  limits  of  the  stellar  universe,  must  be  filled 
with  matter  in  the  form  of  gas,  preeminently  that  of  the 
terrestrial  "^"mosphere.  Any  solid  body  in  space  must, 
by  virtue  of  its  gravitative  energy,  condense  the  gas,  to 
form  an  atmosphere  upon  its  surface,  and  the  density  of 
this  gaseous  envelope  can  readily  be  calculated  when  the 
size  and  mass  of  tlie  body  are  known."  Zollner  then 
proceeds  to  discuss  the  density  of  the  atmospheres  sur- 
rounding the  various  bodies  of  the  solar  system,  and  to 
calculate  that  of  the  interstellary  sj)aces,  where  he  con- 
cludes that  the  gaseous  medium  would  be  so  ra  tliat  it 
"  could  have  no  appreciable  effect  either  iq:)on  i  rays  of 
light  or  upon  the  motion  of  bodies  in  space."  *] 

§  23.  Since  the  days  of  Newton,  however,  no  one,  so 
far  as  I  am  aware,  had  liitherto  considered  the  iiiiorstellary 
matter  from  a  chemical  point  of  view.  In  1874,  as  al- 
ready shown,  the  writer  had,  in  extension  ol  lie  concei)- 
tio.n  of  Humboldt  that  its  condensation  gives  rise  to 
nebula),  ventured  the  suggestion  that  from  an  ethereal 
medium  having  the  same  composition  as  our  own  atmos- 
pliere,  the  chemical  elements  of  the  sun  and  tlie  planets 
have  been  evolved,  in  accordance  with  the  views  of 
Brodie,  Clarke,  and  Lockyer,  by  a  stoichiogenii  ^)rocess : 
*  Amer.  Jour.  Science,  18"  2,  iii.,  47G. 


I      i' 


66 


CELESTIAL  CHEMISTRY 


liv. 


80  that,  in  the  language  of  Newton's  Hypothesis,   "  all 
things  may  be  origin-ited  from  ether." 

§  24.  It  was  not,  however,  until  1878,  that,  from  a 
consideration  of  the  chemical  processes  which  have  gone 
on  at  the  earth's  surface  within  recorded  geological  time, 
I  was  led  to  another  step  in  this  inquiry.  That  all  the 
deoxidized  carbon  found  in  the  earth's  crust  in  the  forms 
of  coal  and  graphite,  as  v/ell  as  that  existing  in  a  diffused 
state,  as  bituminous  or  carbonaceous  matter,  has  come, 
through  vegetation,  from  atmospheric  carbonic  acid,  ap- 
peal's certain.  To  the  same  source  we  must  ascribe  the 
carbonic  acid  of  all  the  limestones  v/hich,  since  the  dawn 
of  life  on  our  earth,  have  been  deposited  from  its  waters 
It  is  through  the  sub-aerial  decay  of  crystalline  silicated 
rocks,  and  the  direct  formation  of  carbonate  of  lime,  or  of 
carbonates  of  magnesia  and  alkalies  which  have  reacted 
on  the  calcium-salts  of  the  primeval  ocean,  that  all  lime- 
stones and  dolomites  have  been  generated.  These,  apart 
from  th3  coaly  matter,  hold,  locked  up  and  withdrawn 
from  the  aerial  circulation,  an  amount  of  carbonic  acid 
which  may  be  probably  estimated  at  not  less  than  200 
atmo,«pheres  equal  in  weight  to  our  own.  That  this 
amount,  or  even  a  thousandth  part  of  it,  could  have 
existed  at  anyone  time  in  our  terrestrial  atmosphere  since 
the  beginning  of  life  on  our  planet  is  inconceivable,  and 
ihht  it  could  be  supplied  from  the  earth's  interior  is  an 
hj^iothesis  equally  untenable. 

§  *'.5.  I  was  therefore  led  to  admit  for  it  an  extra-ter- 
rettriai  .source,  and  to  maintain  that  the  carbonic  acid  has 
thei!?e  giadually  come  into  our  armosphere  to  supply  the 
deti  neiicies  created  by  chemical  processes  at  the  earth's 
S'u  ace.  Since  similar  processes  are  even  now  remov- 
iii  from  our  atmosphere  this  indispensable  element,  and 
fix  g  it  in  solid  forms,  it  follows  that,  except  volcanic 
agency,  which  can  only  restore  a  portion  of  what  was  pri- 
marily derived  from  the  atmosphere,  there  are  on  earth, 
besides  organic  decay,  only  the    artificial    processes  of 


IV.1 


FROM  THE  TIME  OP  NEWTON. 


67 


all 


human  industry  wliioh  can  furnish  carbonic  acid ;  so  that 
but  for  a  supply  of  this  <jas  from  the  interstellary  spaces 
now,  as  in  the  past,  vegetation,  and  consequently  animal 
life  itself,  would  fail  and  perish  from  the  earth,  for  want 
of  this  "  food  of  planets." 

§  26.  Such  were  the  conclusions,  based  on  an  induction 
from  the  facts  of  modern  chemistry  and  geology,  which  I 
enunciated  in  my  papers  in  1878  and  1880,  already  quoted 
in  the  first  part  of  this  essay.  I  was  at  that  time  unac- 
quainted with  the  Hypothesis  of  Newton,  and  with  his 
remarkable  reasoning  contained  in  the  41st  Proposition  of 
the  third  book  of  tlie  Principia^  in  which  he,  so  far  as 
Avas  pijssible  with  the  chemical  knowledge  of  his  time, 
anticipated  my  own  argument,  and  showed  how  and  in 
what  manner  tlie  interstellary  ether  may  really  afford  the 
"food  of  planets"  and,  in  a  sense,  "the  material  principle 
of  life." 

I  have  thus  endeavored  to  bring  before  the  Philosophi- 
cal Society  of  Cambridge  a  brief  history  of  the  develop- 
ment of  this  conception  of  an  interstellary  medium,  and 
to  show  that  the  thought  of  two  centuries  has  done  little 
more  than  confirm  the  almost  forgotten  views  of  Newton. 
It  is  with  feelings  of  peculiar  gratification  that  I  have 
been  able  to  indite  these  pages  within  the  very  walls  of 
the  college  in  which  our  great  philosopher  lived  and 
labored,  and  where,  combining  all  the  science  of  his 
time  with  a  foresight  which  seems  well-nigh  divine,  he 
was  enabled,  in  the  words  of  the  poet,  "  to  think  again 
the  great  thought  of  the  creation."* 

*  Ante,  page  23. 


*Sifc,':J™U»ii  ^.^^.t.. 


''■   .  ''Ill 
V    4 

' , 

V. 

THE  ORIGIN  OF  CRYSTALLINE]  ROCKS. 

This  Essay,  under  the  title  of  "  The  Origin  of  Crystalline  Rocks,  a  Historical 
and  Critical  lievinw,  with  an  account  of  the  Crenltic  Hypothesis,"  was  presented 
and  road  in  abstract  to  the  Koyal  Society  oi  Canada  at  Ottawa,  May  'M,  1S84,  a  pre- 
vious abstract  having  been  given  to  the  National  Acatleniy  of  Sciences  at  Washing- 
ton, April  15,  as  explained  below  in  a  footnote  to  §  70.  It  was  published  in  its 
present  form  in  the  Transactions  of  the  Koyal  Society  of  Canada  for  1H84  (Vol.  II., 
sec.  iii.,  pp.  1  ■  G7).  Tlie  observations  of  Vauhise,  cited  in  §  llO,  appeared  after  the 
presentation  of  this  paper.  Tiie  same  is  true  of  those  of  Murray  and  lieuard, 
referred  to  in  §  95,  though  these  had  previously  been  coumiunicated  to  the  writer. 

I.  —  HISTORICAL  AND   CRITICAL. 

§  1.  The  problem  of  the  origin  of  tlie  crystalline  rocks 
which  cover  so  large  a  part  of  the  earth's  surface,  is  justly 
regarded  as  one  of  fundamental  importance  to  geology, 
and  its  solution  has  been  attempted  during  the  past  cen- 
tury by  many  investigators,  who  have  advanced  widely 
different  hypotheses.  These  it  is  proposed  to  review 
briefly  in  a  historical  sketch  before  proceeding  to  suggest 
a  new  one,  which  it  is  the  object  of  the  present  memoir 
to  bring  forward.  Without  g  >ing  back  to  the  specula- 
tions of  the  ancient  philosophers,  we  find  those  of  the 
last  two  centuries,  Newton,  Descartes,  Leibnitz,  and 
Buffon,  among  others,  accepting  the  hypothesis  of  a 
former  igneous  condition  of  our  planet.  Starting  from 
this  basis,  the  phenomena  of  volcanoes,  and  the  resem- 
blances between  their  consolidated  lavas  and  many  of  the 
crystalline  rocks,  naturally  gave  rise  to  the  notion  of  the 
igneous  origin  of  these,  which  was  formulated  in  the  hy- 
pothesis that  all  such  rocks,  whether  massive  or  schistose, 
were  directly  formed  during  the  cooli  ig  and  consolidation 
of  a  molten  globe. 

§  2.  Playfair,  in  his  "  Illustrations  of  the  Huttonian 
Theory  of  the  Earth,"  tells  us  that  it  was  Lehman,  who, 


V,] 


THE  ORIGIN   OF   CRYSTALLINE   ROCKS. 


69 


ill  17r>6,  first  distinguislied  by  the  name  of  Primitive  the 
ancient  crystalline  rocks,  described  by  him  as  arranged  in 
beds,  -ertical  or  highly  inclined  in  attitude,  and  overlaid 
by  horizontal  stiata  of  secondary  origin.  These  primitive 
rocks  were  by  Lehman  regarded  "  as  parts  of  the  original 
nucleus  of  the  globe,  which  had  undergone  no  alteration, 
but  remained  such  as  they  were  first  created."  This  view 
was  shared  by  Pallas  and  by  De  Luc,  the  latter  of  whom 
at  one  time  considered  the  primitive  rocks  "as  neither 
stratilied  nor  formed  by  water,"  though,  as  Playfair  in- 
forms us,  De  Luc  subsequently  admitted  "  their  formation 
from  aqueous  deposition,  as  the  neptunists  do  in  general."  * 

Pallas  held  a  similar  view,  and,  according  to  Daubrde, 
both  Pallas  and  Saussure  "  admitted,  as  Linnajus  had 
done,  that  all  the  terranes  have  been  formed  by  the 
agency  of  water,  and  that  volcanic  phenomena  are  but 
local  accidents."  Pallas  published  his  "  Observations  on 
Mountains  "  in  1777,  and  Saussure  the  first  volume  of  his 
"  Voyages  dans  les  Alpes  "  in  1779.  It  was  about  1780 
that  the  celebrated  professor  of  Freiberg  began,  in  his 
lectures,  the  exposition  of  his  views,  called  by  Playfair 
"  the  Neptunian  system  as  improved  by  Werner  " ;  though 
his  Classification  of  the  Rocks,  in  which  these  views  were 
finally  embodied,  dates  only  from  1787. 

§  3.  According  to  Werner,  the  materials  which  now 
form  the  solid  crust  of  the  globe  were  deposited  from  the 
waters  of  a  primeval  ocean,  in  which  the  elements  of  the 
crystalline  rocks  were  at  one  time  dissolved,  and  from 
which  they  were  separated  as  chemical  precipitates.  The 
granite,  which  he  regarded  as  the  fundamental  rock,  was 
first  laid  down,  and  was  closely  followed  by  the  gneisses 
and  the  hornblendic  and  micaceous  schists.  When  the 
dissolving  ocean  covered  the  whole  globe  to  a  great  depth, 

*  John  riayfair,  loc.  cit.,  pp.,  160,  102.  The  Theory  of  the  Earth,  by 
James  Ilittton,  first  appeared  in  1785,  and  in  a  second  edition  in  1705. 
riayfalr's  celebrated  exposition  of  it,  here  quoted,  was  published  in  Edin- 
burgh in  1802. 


oaiUn.Ul.Mru,  ^ 


mmt 


TO 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


[V. 


'  (I 


■li-i 


and  its  waters  were  tranquil  and  pure,  the  rocks  depos- 
ited were  exclusively  crystalline,  and,  like  the  ocean,  they 
were  universal.  These  he  distinguished  as  the  Primitive 
rocks. 

At  r.  later  period,  the  depth  of  the  ocean  was  supposed 
to  have  been  diminished  by  the  retreat  of  a  portion  of  the 
waters  to  cavities  within  the  globe ;  a  notion  apparently 
borrowed  from  Leibnitz,  who  imagined  caverns,  left  by 
the  cooling  of  a  formerly  fused  mass,  to  have  subsequently 
served  as  reservoirs  for  a  part  of  the  universal  ocean.  In 
this  second  period,  according  to  Werner,  a  chemical  de- 
position of  silicates  still  went  on,  but  dry  land  having 
been  exposed  and  shallows  formed,  currents  destroyed 
portions  of  the  previously  deposited  masses,  which  were 
also  attacked  by  atmospheric  agents.  By  these  actions 
were  formed  mechanical  sediments,  which  became  inter- 
stratified  with  those  of  chemical  origin.  It  was  during 
this  period  of  coincident  chemical  and  mechanical  deposi- 
tion that  were  formed  the  Intermediate  or  Transition 
rocks  of  Werner,  which,  from  the  conditions  of  their  for- 
mation, necessarily  covered  portions  only  of  the  universal 
Primitive  series.  At  a  still  later  period,  marked  by  a 
farther  diminution  of  the  superficial  waters,  were  laid 
down  the  Secondary  rocks  of  Werner,  at  a  time  when  the 
sea  no  longer  produced  mineral  silicates,  and  had  assumed 
essentially  its  present  composition. 

§  4.  The  Primitive  rocks,  according  to  this  hypothesis, 
were  those  composed  entirely  of  chemical  deposits,  which 
are  either  crystallized  or  have  a  tendency  to  crystalliza- 
tion, and  in  which  the  action  of  mechanical  causes  cannot 
be  traced.  In  the  Transition  series,  the  products  of 
chemical  and  mechanical  processes  are  intermingled,  and 
materials  derived  from  the  disintegration  and  decay  of 
Primitive  rocks  are  present ;  while  the  rocks  of  the 
Secondary  series  were  formed  from  the  ruins  alike  of  the 
Pi'imitive  and  the  Transition  series.  During  the  process 
of   their  consolidation,  the   various  strata  having  been 


v.i 


THE  ORIGIN   OF  CRYSTALLINE   ROCKS. 


71 


broken,  fissures  were  formed  through  wliich  the  surplus 
waters  retired  to  the  internal  cavities,  depositing  on  the 
walls  of  the  fissure^"  through  which  the}'  descended  the 
various  matters  still  iield  in  solution.  In  this  way  were 
formed  metalliferous  and  other  mineral  veins. 

The  aqueous  solution  in  which  all  these  crystalline 
rocks  were  at  first  dissolved  was  described  by  Werner 
and  his  disciples  as  a  chaotic  liquid,  and  he  even  desig- 
nated the  rocks  themselves  as  chaotic,  "  because  they  were 
formed  when  the  earth's  surface  was  a  chaos."  These 
Primitive  rocks,  consisting  of  the  granite  and  the  over- 
lying crystalline  sciiists,  covered  the  whole  earth,  and 
their  geograi)hical  inequalities  were  due  to  the  original 
deposition,  which  did  not  yield  a  regular  surface,  but 
presented  elevations,  upon  the  slopes  of  which  were  sub- 
sequently laid  down  the  Transition  strata. 

Such,  according  to  Werner,  was  the  origin  of  all  rock- 
masses  except  recent  alluvion^,  deposits  of  obviously 
organic  origin,  and  the  ejections  of  volcanoes,  which  he 
conceived  to  be  due  to  the  subterraneous  combustion  of 
carbonaceous  deposits.  In  the  earlier  ages  of  the  world 
there  were,  according  to  him,  no  volcanoes  and  no  evi- 
dences of  subterranean  heat.  Neither  in  the  formation  of 
granite,  of  basalt,  of  the  crystalline  schists,  or  of  mineral 
veins,  or  in  the  displacements  of  the  strata  to  be  seen  in 
the  deposits  of  various  ages,  did  he  recognize  any  mani- 
festations of  an  internal  activity  of  the  earth.* 

§  5.  We  now  pass  to  the  consideration  of  the  rival 
geological  theory  of  Hutton,  which  was  developed  at  the 
same  time  with  that  of  Werner.     Saussure,  as  early  as 

*  In  preparing  the  foregoing  synopsis  of  the  views  of  Werner,  I  have 
followed  ill  part,  the  exposition  of  his  system  given  by  Mnrray  in  his  Re- 
view of  'Playfair's  Illnstrations  of  the  Iluttonian  Tlieory,  pnblishecl 
anonymously  in  Edinburgh  in  1802;  in  part  the  statements  to  be  found 
in  Playfair,  in  Bakewell,  in  Lyell,  and  in  Naumann;  and  also  the  excel- 
lent analysis  given  by  Daubree  in  his  fctudes  et  Experiences  Synthetiques 
8ur  le  Metamorphisme,  et  sur  la  Formation  des  Roches  Cristallines; 
Paris,  1860. 


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72 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


[V. 


1776,  had  ascribed  to  aqueous  infiltration  the  granitic 
veins  in  the  Valorsine,  and  others  near  Lyons  —  a  view 
which  was  shared  by  Werner,  who,  from  their  similar 
constitution,  conceived  that  the  formation  of  massive  and 
stratiform  granitic  rocks  had  taken  place  under  conditions 
•like  tliose  which  gave  rise  to  the  veins  in  question,  and 
then  extended  this  view  to  other  veins  and  masses  of  what 
we  must  regard  as  injected  or  irrupted  rocks,  including 
not  only  granites  but  dolerites  and  basalts. 

Hutton  and  his  interpreter,  Playfair,  on  the  other  hand, 
regarded  all  granitic  veins  as  having  been  filled  by  injec- 
tion with  matter  in  a  state  of  igneous  fusion,  repudiating 
the  notion  of  Saussure  and  of  Werner  that  such  materials 
could  be  formed  by  crystallization  from  aqueous  solutions. 
Granitic  veins,  according  to  Hutton,  are  in  all  cases  bit 
ramifications  of  great  masses  of  granite,  themselves  often 
concealed  from  view.  "In  Hutton's  theory,  granite  is 
regarded  of  more  recent  formation  than  the  strata  incum- 
bent upon  it ;  as  a  substance  which  has  been  melted  by 
heat,  and  which,  forced  up  from  the  mineral  regions,  has 
elevated  the  strata  at  the  same  time."  *  From  this  con- 
dition of  igneous  liquidity,  he  supposed,  had  crystallized 
alike  quartz  and  feldspar,  as  well  as  tourmaline  and  the 
other  minerals  sometimes  found  in  granitic  veins.  Granite 
is  elsewhere  declared  by  him  to  be  matter  fused  in  the 
central  regions  of  the  earth. 

§  6.  With  Werner,  granite  was  the  substratum  under- 
lying all  other  known  rocks,  simply  because  it  had  been 
the  first  deposit  from  the  chaotic  watery  liquid,  and  it  was 
said  to  pass  into  or  to  alternate  with  the  distinctly  strati- 
form or  schistose  crystalline  rocks.  In  this  view  of  its 
geognostical  relations,  Werner  was  strictly  correct  if  by 
granite  we  understand  the  massive  or  indistinctly  strati- 
form aggregate  which  makes  up  what  some  call  granite 
and  others  fundamental  granitoid  gneiss.  This  is  what  I 
have  called  an  indigenous  rock,  which  may  be  with  or 

*  Playfair,  Illustrations,  etc.,  p.  89. 

'  If         ^     ■  ■  ■ 


v.] 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


73 


without  apparent  stratification.  We  must,  however,  dis- 
tinguish, besides  this  first  type  of  crystalline  rock,  —  the 
underlying  granite  of  Werner,  —  two  others  which, 
though  mineralogically  similar,  and  often  confounded,  are 
geognostically  distinct.  Of  these,  what  I  have  called 
EXOTIC  rocks  consist  apparently  of  softened  and  displaced 
portions  of  aggregates  of  the  first  type,  and  are  met  with 
alike  in  dikes  and  in  masses  of  greater  or  less  size,  in- 
truded or  irrupted  among  the  stratified  or  indigenous 
rocks.  These  are  the  typical  granites  of  Hutton.  The 
third  type  includes  those  concretionary  masses  of  granitic 
material  formed  in  fissures  or  cavities,  which  are  evidently 
deposits  from  aqueous  solutions.  These  are  the  infiltrated 
veins  of  Saussure  and  of  Werner,  and  are  what  I  have 
designated  endogenous  rocks. 

§  7.  By  keeping  in  view  this  threefold  distinction 
between  indigenous,  exotic,  and  endogenous  granitic 
aggregates,  as  I  have  long  since  endeavored  to  show,  the 
obscurities  and  apparently  contradictory  views  of  different 
observers  are  easily  explained.  These  distinctions  are 
recognized  in  other  crystalline  rocks  than  granite.  Under 
the  name  of  crystalline  limestones,  as  is  well  known,  have 
been  included  both  indigenous  and  endogenous  masses. 
The  question  whether  or  not  certain  crystalline  silicated 
rocks  are  to  be  regarded  as  eruptive,  is  seen  to  be  of 
minor  importance,  when  we  consider  that  it  is  possible 
for  indigenous  crystalline  deposits  to  appear  in  the  rela- 
tion of  exotic  masses,  whether  displaced  in  a  softened  and 
plastic  condition,  as  more  generally  happens,  or  else 
forced,  in  rigid  masses,  among  softer  and  more  yielding 
strata,  as  appears,  from  the  observations  of  StaptT,  to  be 
the  case  of  the  serpentines  of  Mount  St.  Gothard.* 

§  8.  Werner  argued,  and,  as  we  shall  endeavor  to  show, 
correctly,  from  their  analogies  with  concretionary  granitic 
veins,  that  all  granitic  rocks  were  deposited  from  water, 
and  are  consequently  indigenous  or  endogenous  in  origin. 

*  See  Essay  X.,§12&-1S0.  .' 


74 


THE  OKIGIN  OF  CRYSTALLINE  ROCKS. 


[V. 


He  denied  the  existence  of  exotic  and  of  igneous  rocks. 
Hutton,  on  the  contrary,  from  the  phenomena  of  exotic 
granites,  and  the  analogies  observed  between  these  and 
basalts  and  modern  volcanic  rocks,  was  led  to  assume  an 
igneous  and  exotic  origin  for  all  save  the  clearly  strati- 
form crystalline  rocks.  Metalliferous  lodes,  also,  he  sup- 
posed to  have  been  formed,  like  granitic  veins,  by  igneous 
injection  from  below.  While  the  disciples  of  Werner 
denied  the  igneous  origin  of  basalts,  and  even  of  obsidian, 
Hutton  and  his  school,  on  the  other  hand,  maintained  that 
the  agates  often  found  in  erupted  rocks  were  formed  by 
lire.  Playfair  reasons :  —  "  The  fluidity  of  the  agate  was 
therefore  simple  and  unassisted  by  any  menstruum"; 
that  is,  it  was  due  to  heat,  and  not  to  solution ;  while,  in 
the  case  of  mineral  veins,  their  closed  cavities  were  held 
to  "  afford  a  demonstration  that  no  chemical  solvent  was 
ever  included  in  them."  *  These  cavities  were  regarded 
as  due  to  the  contraction  consequent  on  the  cooling  of 
injected  igneous  material.  i  ^  , 

'  §  9.  The  basic  rocks,  included  by  Hutton  under  the 
common  names  of  basalt  and  whinstone,  are  regarded  by 
him  as  similar  in  origin  to  granite,  and  called  "  unerupted 
lavas."  He  elsewhere  says  that  "  whinstone  is  neither  of 
volcanic  nor  of  aqueous,  but  certainly  of  igneous  origin," 
that  is  to  say  plutonic.  Playfair  distinguishes  between 
what  he  calls  the  volcanic  and  the  plutonic  theory  of  basalt. 
But  while  Hutton  ascribed  a  plutonic  origin  to  basalt 
and  to  granite,  he  did  not,  as  some  have  done,  assign  a 
similar  plutonic  origin  to  gneiss  and  other  crystalline 
schists.  These  were  by  Werner  declared  to  result  from  a 
continuation  of  the  same  process  which  gave  rise  to 
granite,  and  to  graduate  into  it.  Gneiss  is  held  both  by 
Wernerians  and  by  modern  plutonists  to  be  but  a  strati- 
form granite,  and  both  of  these  rocks  are  believed  by  the 
one  school  to  be  aqueous  and  by  the  other  to  be  igneous 
in  origin. 

♦  Playfair,  Illustrations,  etc.,  pp.  79  and  260. 


v.i 


THE  ORIGIN  OP  CRTSTALLINB  ROCKS. 


75 


In  the  system  of  Hutton,  however,  a  wide  distinction  is 
made  between  the  two  rocks.  Gneiss  was  no  longer  a  prim- 
itive or  original  rock,  as  taught  by  Lehman  and  by  Wer- 
ner, but,  like  the  other  crystalline  schists,  designated  by 
Hutton  as  Primary,  was  supposed  to  be  "  formed  of  mate- 
rials deposited  at  the  bottom  of  the  sea,  and  collected 
from  the  waste  of  rocks  still  more  ai)cient."  In  his  sys- 
tem "  water  is  first  employed  to  arrange,  and  then  fire  to 
consolidate,  mineralize,  and  lastly  to  elevate  the  strata ; 
but  with  respect  to  the  unstratified  or  crystallized  sub- 
stances the  action  of  fire  alone  is  recognized."  *  Hutton 
also  conceived  the  pressure  of  the  waters  of  a  superincum- 
bent ocean  to  exert  an  important  influence  in  the  consoli- 
dation of  the  sediments.  He  was  thus  a  plutonist  only  so 
far  as  regards  granite  and  other  unstratified  rocks,  while 
in  maintaining  a  detrital  origin  for  the  crystalline  schists 
he,  as  Naumann  has  remarked,  may  be  regarded  as  the 
author  of  the  so-called  metamorphic  hypothesis  of  their 
origin.  Playfair  himself  declares  of  Hutton's  system: 
"We  are  to  consider  this  theory  as  hardly  less  distin- 
guished from  the  hypothesis  of  the  vulcanists,  in  the  usual 
sense  of  this  appellation,  than  it  is  from  that  of  the  nep- 
tunists  or  disciples  of  Werner."  f 

§  10.  It  was  no  part  of  Hutton's  plan  to  discuss  the 
origin  of  those  more  ancient  rocks,  which  had,  according 
to  him,  furnished  oy  their  disintegration  the  materials  for 
the  primary  stratified  rocks.  It  was,  in  the  language  of 
Playfair,  a  system  "  where  nothing  is  to  be  seen  beyond 
the  continuation  of  the  present  order."  "  His  object  was 
not  .  .  .  like  that  of  most  other  theorists  —  to  explain  the 
first  origin  of  things."  This  system,  as  interpreted  by  his 
school,  asserts  the  conversion  of  detrital  rocks  into  masses 
indistinguishable  from  those  of  truly  igneous  origin,  which 
were  the  sources  of  the  first  detritus.  The  changes  which 
it  assumed  to  be  wrought  by  the  alternate  action  of  water 

*  Playfair,  Illustrations,  etc.,  pp.  12,  131. 

t  Biography  of  Hutton;  Playfair' s  Works,  vol.  iv.,  p.  52. 


!'J 


I'i 


76 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


[V. 


and  fire  on  the  earth's  crust  were  not  supposed  to  be  lim- 
ited by  any  external  conditions  in  the  nature  of  things, 
and  were  compared  by  Playfair  to  the  self-limited  pertur- 
bations in  the  movements  of  the  heavenly  bodies,  in  which, 
as  in  the  geological  changes  of  the  earth's  crust,  "  we  dis- 
cern no  mark  either  of  the  commencement  or  termination 
of  the  present  order." 

^  11.  Hntton's  system  is  thus  concisely  resumed  by 
Daubrde :  —  "  The  atmosphere  is  the  region  in  which  the 
rocks  decay;  their  ruins  accumulate  in  the  ocean,  and  are 
there  mineralized  and  transformed,  under  the  double  influ- 
ence of  pressure  and  the  internal  heat,  into  crystalline 
rocks  having  the  aspect  of  the  older  ones.  These  re-fo'^med 
rocks  are  subsequently  uplifted  by  the  same  internal  heat, 
and  destroyed  in  their  turn.  The  disintegration  of  one 
part  of  the  globe  thus  serves  constantly  for  the  reconstruc- 
tion of  other  parts,  and  the  continued  absorption  of  the 
underlying  deposits  produces  incessantly  new  molten 
rocks,  which  may  be  injected  among  th  j  overlying  sedi- 
ments. AVe  havs  thus  a  system  of  destruction  and  reno- 
vation of  which  we  can  discern  neither  the  beginning  nor 
the  end."  * 

§  12.  It  was  this  perpetual  round  of  geological  changes, 
which  took  no  account  either  of  a  beginning  or  an  end, 
that  led  the  theologians  of  his  day  \,^  oppose"  the  system 
of  Hutton.  On  the  other  hand,  in  the  system  of  Werner, 
which  taught  the  fashioning  of  the  present  order  of  our 
globe  from  a  primeval  chaos  beneath  the  waters  of  a  uni- 
versal ocean,  they  saw  a  conformity  with  the  Hebrew 
cosmogony,  which  recommended  to  them  the  neptunian 
hypothesis.  Hence  the  theological  element  which,  as  is 
well  known,  entered  so  largely''  into  the  controversies  of 
the  vulcanists  and  the  neptunists  at  the  beginning  of  this 
century,  and  the  suspicion  with  which  the  partisans  of 
Hutton  were  then  regarded  by  the  Christian  world. 

The  extreme  neptunian  views  of  Werner,  however,  soon 

*  Daubr^e,  Etudes  et  Experiences,  etc.,  p.  12. 


v.] 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


TT 


fell  into  disfavor.  The  visible  evidences  of  the  extrusion 
of  trappean  rocks  in  a  heated  and  softened  state,  observa- 
tions showing  the  augmentation  of  the  temperature  in 
mines,  and  the  phenomena  of  thermal  springs  and  volca- 
noes, soon  turned  the  scale  in  favor  of  Button's  views. 
There  were  not  wanting  those  who  attempted  to  unite  the 
Wernerian  hypothesis  with  that  of  an  igneous  globe,  and 
who  supposed  a  primeval  chaotic  ocean,  to  the  waters  of 
which,  heated  by  the  mass  below,  and  kept  at  a  high  boil- 
ing-point by  the  pressure  of  an  atmosphere  of  great  den- 
sity, was  ascribed  an  exalted  solvent  power. 

§  13.  Such  a  modified  neptunian  view  was  advanced 
by  De  la  Beche.  In  his  "  Researches  in  Theoretical  Geol- 
ogy," published  in  1837,  he  favored  the  notion  of  an  unoxi- 
dized  nucleus,  as  suggested  by  Davy,  and  held  to  a  solid 
crust  resting  on  a  liquid  interior,  and  presenting,  from  the 
first,  irregularities  of  surface.  He  then  speaks  of  "the 
much  debated  question  "  whether  the  crystalline  stratified 
rocks  "  have  resulted  from  the  deposit  of  abraded  portions 
of  pre-existing  rocks  mechanically  suspended  in  water,  or 
have  been  chemically  derived  from  an  aqueous  or  an  ign'.- 
ous  fluid  in  which  their  elements  were  disseminated." 
We  have  in  this  paragraph  three  distinct  hypotheses  pre- 
sented. Two  years  later  he  clearly  declared  for  the  sec- 
ond of  them. 

While  admitting  the  crystallization  of  detrital  matter 
in  proximity  to  intrusive  rocks,  De  la  Beche  objected  to 
what  he  called  the  "sweeping  hypothesis"  of  Hutton  and 
his  school.  He  supposed  that,  in  the  cooling  of  our  planet 
from  an  igneous  fluid  state,  "  there  must  have  been  a  time 
when  solid  rock  was  first  formed,  and  also  a  time  when 
heated  fluids  rested  upon  it.  The  latter  would  be  condi- 
tions highly  favorable  to  the  production  of  crystalline  sub- 
stances, and  the  state  of  the  earth's  surface  would  then  be 
so  totally  different  from  that  which  now  exists,  that  min- 
eral matter,  even  when  abraded  from  any  part  of  the 
earth's  crust  which  may  have  been  solid,  would  be  placed 


78 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


[V. 


under  very  different  conditions  at  these  different  periods." 
He  suggests  that  there  would  be  "  a  mass  of  crystalline 
rocks  produced  at  first,  which,  however  they  may  vary  in 
minor  points,  should  still  preserve  a  general  character  and 
aspect,  the  result  of  the  first  changes  of  fluid  into  solid 
matter,  crystalline  and  sub-crystalline  substances  prevail- 
ing, intermingled  with  detrital  portions  of  the  same  sub- 
stances abraded  by  the  movements  of  the  heated  and  first- 
formed  aqueous  fluids.  In  the  gneiss,  mica-slate,  chloritic- 
slate,  and  other  rocks  of  the  same  kind,  associated  together 
in  great  masses,  and  covering  large  areas  in  various  parts 
of  the  world,  we  seem  to  have  those  mineral  bodies  which 
were  first  formed.  The  theory  of  a  cooling  globe,  such 
as  our  planet,  supposes  a  transition  from  a  state  of  things 
highly  favorable  to  the  production  of  crystalline  rocks,  to 
one  in  which  masses  of  these  rocks  would  be  more  rarely 
formed.  Hence  we  could  never  expect  to  draw  fine  lines 
of  demarcation  between  the  products  of  one  state  of  things 
and  those  of  the  other,"  * 

§  14.  Still  later,  in  1860,  we  find  a  similar  view  sug- 
gested by  Daubrde  as  a  probable  hypothesis.  He  goes 
back  in  imagination  to  a  time  when  the  waters  of  our 
planet,  as  yet  uncondensed,  surrounded  the  globe  with  a 
dense  envelope  estimated  to  possess  a  weight  equal  to  250 
atmospheres.  "  The  surface  of  the  earth  was  at  this  time 
at  a  very  high  temperature,  and  if  silicates  then  existed 
they  must  have  been  formed  without  the  co-operation  of 
liquid  water.  Later,  however,  when  it  began  to  assume  a 
liquid  state,  the  water  must  have  reacted  upon  the  pre- 
existing silicates  upon  which  it  reposed,  and  then  have 
given  rise  to  a  whole  series  of  new  products.  By  a  veri- 
table metamorphic  action,  the  water  of  this  primitive 
ocean,  penetrating  the  igneous  masses,  caused  their  primi- 
tive characters  to  disappear,  and  formed,  as  in  our  tubes, 
crystallized  minerals  from  the  matters  which  it  was  able 

*  De  la  Beclie,  Geology  of  Cornwall  and  Devon,  pp.  33-34;  also  Re- 
searches in  Theoretical  Geology. 


T.1 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


79 


to  dissolve.  These  matters,  formed  or  suspended  in  the 
liquid,  would  then  be  precipitated,  and  give  rise  to  depos- 
its presenting  different  characters  as  the  temperature  of 
the  liquid  diminished."  He  then  inquires,  "  Were  these 
cUfferent  periods  of  chemical  decomposition  and  recompo- 
sition,  in  which  aqueous  action  Qa  vote  humide')  intervenes 
under  extreme  conditions  which  approach  those  of  igneous 
action  (la  voie  scehe),  the  era  of  the  formation  of  granite 
and  of  the  azoic  and  crystalline  schists?  We  cannot 
affirm  this  in  an  absolute  manner,  but  we  may  presume  it, 
especially  when  we  consider  that  on  this  hypothesis  there 
must  have  been  formed  two  principal  products,  the  one 
massive  and  the  other  presenting  evidences  of  sedimenta- 
tion, passing  into  each  other  gradually,  as  is  the  case  with 
granite  and  gneiss.  In  any  case,  it  cannot  be  contested 
that  if  there  was  a  time  when  the  rocks  were  exclusively 
under  the  dominion  of  fire,  they  passed  under  that  of 
water  at  an  epoch  much  more  remote  than  we  liave  hith- 
erto admitted.  The  influence,  now  established,  of  water 
in  the  crystallization  of  silicates,  no  longer  permits  any 
doubt  on  this  point.  We  cannot  perhaps  now  find  any- 
where upon  the  globe  rocks  of  which  it  may  be  affirmed 
with  certainty  that  they  have  been  formed  by  igneous 
action,  without  the  intervention  of  water."  * 

§  15.  To  give  some  notion  of  the  temperature  of  the 
first  water  precipitated  on  the  earth's  cooling  surface, 
Daubrde  calculates  that  the  waters  of  the  present  ocean, 
estimating  their  mean  depth  at  3500  metres,  would,  if 
spread  uniformly  over  the  earth's  surface,  have  a  thick- 
ness of  2563  metres,  which,  if  converted  into  vapor, 
would  correspond  to  a  pressure  of  248  atmospheres,  a 
weight  which  would  be  augmented  by  the  presence  of 
other  vapors  and  gases.  "No  liquid  water  could  there- 
fore rest  upon  the  earth  until  its  temperature  had  fallen 
below  that  which  would  give  to  the  vapor  of  water  a  ten- 
sion of  250  atmospheres"  at  least.    When  we  consider 

*  Daubr^e,  Etudes  et  Experiences  Synth^tiques,  etc.,  pp.  121, 122. 


80 


THE  ORIGIN  OF  CBYSTALLINB  ROCKS. 


1*^ 


|i 


that  a  tension  of  only  fifty  atmospheres  of  steam  corre- 
sponds, according  to  Arago  and  Dulong,  to  a  temperature 
of  265''.89  centigrade,  we  can  form  some  conception  of 
the  temperature  corresponding  to  a  tension  five  times  as 
great ;  which,  on  this  hypothesis,  would  have  been  that 
of  tho  first  waters  precipitated  on  the  cooling  planet,  re- 
alizing many  of  the  conditions  attained  by  this  ingenious 
experimenter  when  he  subjected  mineral  silicates  to  the 
action  of  water  in  tubes,  at  temperatures  of  from  400°  to 
600°  centigrade. 

It  is  unnecessary  to  point  out  that  Daubrde  here  at- 
tempts to  adapt  Werner's  neptunian  hypothesis  to  that  of 
a  once  fused  and  cooling  globe,  and  to  find,  like  De  la 
Beche,  in  the  highly  heated  primeval  ocean,  the  chaotic 
liquid  which,  according  to  the  Uiaster  of  Freiberg,  was 
the  menstruum  which  at  one  time  held  in  solution  the  ele- 
ments of  the  primitive  rocks.  The  experiments  of  Dau- 
br^e  in  liis  tubes,  above  referred  to,  are  of  great  impor- 
tance in  this  connection,  and  will  be  considered  farther 
on,  in  the  third  part  of  this  paper. 

§  16.  The  Huttonians  early  borrowed  the  notion  of  a 
granitic  substratum  from  Werner,  and  supposed  the  earth 
when  first  cooled  to  have  had  a  surface  of  granite. 
Hutton,  true  to  his  thesis,  avoided  the  question  of  the 
primal  rock.  His  reasonings,  according  to  Playfair, 
"  leave  no  doubt  that  the  strata  which  now  compose  our 
continents  are  all  formed  from  strata  more  ancient  than 
themselves ;  *  while,  as  we  have  seen,  ihe  intruded  gran- 
ites were  looked  upon  as  but  fused  and  displaced  portions 
of  underlying  strata.  The  granitic  character  of  the  rocks 
which  antedated  aqueous  disintegration  was,  however,  a 
matter  of  legitimate  inference,  and  his  disciple,  Maccul- 
loch,  supposed  the  earth  when  first  cooled  to  have  been 
"  a  globe  of  granite."    Later,  in  1847,  filie  de  Beaumont, 


*  Playfair's  Biography  of  James  Hutton,  in  Playfair's  complete 
works,  4  vols.,  Edinburgh,  1822;  see  vol.  iv.,  pp.  33-81.  His  lllustnitions 
of  the  Iluttouian  Theory  will  there  be  found  reprinted  in  vol.  i. 


[V. 


jrre- 
,ture 
m  o£ 
es  as 
that 
jt,  ve- 
luious 
;o  the 
00°  to 


▼.] 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


81 


ere  ftt- 
tliat  of 
De  la 
chaotic 
rg,  was 
the  ele- 
of  Dau- 
,t  impor- 
.  farther 

lion  of  a 
ihe  earth 
granite, 
m  of  the 
Playfair, 
mose  our  . 
ient  than 
[led  gran- 
i  portions 
the  rocks 
jowever,  a 
1    Maccul- 
[lave  been 
ieaumont, 

'8   complete 
1  lUusti-ations 

il.  1. 


starting  from  the  hypothesis  of  a  cooling  liquiil  globe, 
imagined  it  "  a  ball  of  molten  matter,  on  the  surface  of 
which  the  first  granites  crystallized."  * 

§  17.  It  sliould  here  be  mentioned  that  Poulett  Scrope, 
in  1825,  put  forth  what  lie  called  "A  New  Theory  of  tho 
Earth,"  in  which  he  supposes  "  the  mass  of  the  globe,  or 
at  least  its  external  zone  to  a  considerable  depth,  to  have 
been  originally  (that  is  at  or  before  the  moment  in  which 
it  assumed  the  position  it  now  holds  in  the  planetary  sys- 
tem) of  a  granitic  composition,  composed  probably  of  the 
ordinary  elements  of  granite,  and  having  a  very  large 
grain  ;  the  regular  crystallization  having  been  favored  by 
the  circumstances  under  which  it  pre\  ously  took  place, 
though,  as  to  what  these  circumstances  were,  I  do  not 
venture  to  hazard  a  supposition."  He  farther  says,  "If 
then  we  imagine  a  general  intumescence  of  an  intensely 
heated  bed  of  granite,  forming  the  original  surface  of  the 
globe,  to  have  been  succeeded  by  a  period  in  which  the 
predominance  was  acquired  by  the  repressive  force  occa- 
sioned by  the  condensation  of  the  waters  on  its  surface, 
and  the  deposition  from  them  of  various  arenaceous  and 
sedimental  strata  (the  transition  series),  the  structure  of 
the  gneiss-formation  is  at  once  simply  explained.  This 
structure  may  have  been  subsequently  increased  by  the 
friction  of  the  different  laminte  against  one  another  as 
they  were  urged  forward  in  the  direction  of  their  plane 
surfaces,  towards  the  orifice  of  protrusion,  along  the  ex- 
panding granite  beneath;  the  laminse  being  elongated, 
and  the  crystals  forced  to  arrange  themselves  in  the  direc- 
tion of  the  movement."  This  implies  an  exoplutonic  ori- 
gin of  gneiss. 

Later  in  the  same  essay,  however,  Scrope  supposes  an 
intensely  heated  ocean,  holding  in  solution  great  amounts 
of  silica,  and  having,  at  the  same  time,  suspended  in  its 
waters,  feldspar,  quartz,  and  mica,  derived  from  the  disin- 


*  Sur  les  Emanations  Volcaniques  et  Metallifferes. 
de  Fr.  (2)  iv. 


Bull.  Soc.  Geo!. 


82 


THE  OIIIGIN  OF  CRYSTALLINE  BOCKS. 


It. 


tegration  of  the  underlying  granite.  These  suspended 
materials  were  deposited  and  consolidated  into  gneiss,  and 
later,  the  dissolved  silica  precipitating,  with  some  enclosed 
mica,  as  the  ocean  cooled,  gave  rise  to  mica-schists.  In 
this  last,  we  see  the  germ  of  the  therraochaotic  hypothe- 
sis, while  in  preceding  statements  of  Scrope  we  have  out- 
lined the  volcanic  and  metamorphic  hypothesis  of  Dana, 
to  bo  noticed  farther  on.* 

§  18.  That  such  a  primitive  granite  had  been  the 
source  of  gneiss,  was  taught  by  Beroldingen,  "who  main- 
tained that  all  the  rocks  of  granitic  character  having  an  ap- 
pearance of  stratification,  are  granites  of  secondary  forma- 
tion, or  regenerated  granites,  similar  in  their  origin  to 
sandstones";  a  notion  which  was  vigorously  combated 
by  Saussure,t  who  held,  as  we  have  seen,  to  the  neptunian 
theory  of  the  origin  of  these  rocks.  The  detrital  hypoth- 
esis, which  he  opposed,  was  however  strenuously  defended 
by  Ilutton  and  his  school,  and  especially  by  Boue  and  by 
Lyell.  To  the  former  belongs  the  first  definite  attempt  to 
explain  how  uncrystalline  sediments  like  graywacke  and 
clay-slate  might  be  changed  into  crystalline  rocks  such  as 
gneiss  and  mica-schist.  Of  his  views,  put  forth  in  1822 
and  1824,  Naumann  remarks,  "  Boue  first  understood  how 
to  bring  this  theory  into  more  decided  harmony  with  the 
details  of  geological  phenomena,  and  besides  invoking  the 
internal  heat,  brought  to  his  assistance  emanations  of 
gases  and  vapor  from  the  earth's  interior  to  explain  the 
alteration  of  sedimentary  slates  into  gneiss  and  mica- 
schist."    He  imagined  under  these  conditions  "  a  sort  of 

*  Scrope,  Considerations  on  Volcanoes,  etc.,  1825,  pp.  225-228.  Tlie 
cosmogony  of  Scrope  was  fantastic  in  tlie  extreme;  he  conjectured  tlie 
solid  granitic  earth  to  have  been  detached  from  the  sun  as  an  irregular 
mass,  and  compared  it  to  an  aerolite.  [In  rewriting  his  book  on  Volca- 
noes for  a  new  edition,  in  1802,  Scrope  omitted  his  Theory  of  the  Earth, 
and  did  not  attempt  a  cosmogony,  but  maintained  the  views  already 
expressed  by  him  as  to  the  granitic  nature  of  the  exterior  of  the  primitive 
earth,  which  he  supposed  to  be  intensely  heated,  and  solid  to  the  centre. 
(Ed.  of  1872,  pp.  300,  305. )] 

t  Voyages  dans  les  Alpes  (1796),  vol.  vili.,  pp.  55,  64. 


v.] 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


88 


jn  the 
(  main- 
;  an  ap- 
forma- 
igm  to 
(Hibated 
iptuuian 
hypoth- 
leiended 
j  and  by 
•,tempt  to 
[icke  and 
;s  such  as 
.  in  1822 
itood  how 
Avith  the 
•oking  the 
lations  oi 
:plain  the 
ind  mica- 
u  a  sort  of 


igneous  liquefaction,  followed  by  a  cooling  process,  which 
permitted  a  crystalline  arrangement  and  a  development  of 
new  mineral  species  without  destroying  or  deranging 
notably  the  original  laminated  structure."  * 

§  19.  These  views  were  adopted  in  1838,  in  his  "Prin- 
ciples of  Geology,"  by  Lyell,  who  designated  strata  sup- 
posed to  have  been  thus  transformed  by  the  name  of 
"hypogene  metamorphic  rocks";  a  title  intended  to  indi- 
cate a  metamorphism  which  took  place  in  the  depths  of 
the  earth's  crust,  and  proceeded  from  below  upwards. 
Under  this  name,  Lyell  first  popularized  the  Huttonian 
view  as  extended  by  Boue,  which  may  be  conveniently  des- 
ignated as  the  METAMORPHIC  hypothesis  of  the  origin  of 
crystalline  rocks. 

Its  plausibility  has  led  to  the  adoption  of  this  theory  by 
many  geologists  during  the  past  fifty  years.  Some,  un- 
willing to  admit  the  influence  of  a  high  temperature  in 
such  change,  have  imagined  it  to  result  from  causes 
operating  at  ordinary  temperatures  during  very  long  j)e- 
riods.  As  regards  "  the  nature  of  these  transforming  pro- 
cesses, Gustaf  Bischof  and  Haidinger  were  inclined  to 
suppose  that  a  long-continued  percolation  of  water  through 
the  rocks  produced  an  alteration  of  their  substance  and  a 
recrystallization,  in  the  same  way  as  must  have  taken 
place  in  the  production  of  certain  pseudombrphs  by  alter- 
ation." f  Hence  the  significance  of  the  often  repeated 
dictum  that  "metamorphism  is  pseudomorphism  on  a 
broad  scale." 

By  a  further  application  of  the  notions  derived  fiom 
the  study  of  epigenic  or  replacement-pseudomorphs,  which 
show  in  many  cases  the  partial  or  even  the  total  replace- 
ment of  the  original  elements  of  a  mineral  species,  consti- 
tuting what  has  been  appropriately  designated  metasoma- 

•  Boue,  Annales  des  Sciences  Naturelles,  August,  1824,  p.  417,  cited 
by  Naumann. 

t  Naumanu,  Lehrbuch  der  Geognosie  (1857),  2d  ed.,  vol.  ii.,  pp.  160-170. 
We  shall  have  frequent  occasion  in  these  pages  to  quote  from  this  section 
of  Naumann's  Lehrbuch. 


S4: 


THE  OETGIN  OF  CRYSTALLINE  KOCKS. 


P. 


tism,  a  METASOMATio  hypothesis  of  the  origin  of  crystal- 
line rocks  has  been  arrived  at,  to  which  we  shall  revert 
farther  on. 

§  20.  Regarding  the  metamorphic  hypothesis,  we  may 
remark,  as  Naumann  has  done,  that  the  very  transforma- 
tion assumed,  namely,  that  of  mechanical  sediments  into 
crystalline  rocks,  remains  to  be  proved.  In  his  "Lehr- 
buch  der  Geognosie  "  in  1857,  while  still  admitting  the 
metamorphic  origin  of  certain  limited  areas  of  crystalline 
schists,  Naumann  declared  that  the  facts  were  "  not  all  fa- 
vorable to  the  baseless  iiypothesis  which  is  now  carried  to 
extremes."  Such  an  origin  of  crystalline  rocks  was  denied 
by  the  neptunians,  who  held  to  the  direct  crystallization 
of  these  rocks  from  a  chaotic  watery  liquid,  for  which 
reason  we  may  conveniently  and  appropriately  call  their 
view  the  chaotic  hypothesis.  It  is  also  denied  by  those 
who  hold  these  rocks  to  be  of  simple  igneous  oiigin,  the 
first  products  of  a  cooling  globe,  a  view  which  we  may 
call  the  ENDOPLUTONIC  hypothesis ;  and  in  part  by  those 
who  advocate  what  we  shall  call  the  exoplutonic  or  vol- 
canic hypothesis  of  their  origin. 

We  have  already  noticed  at  length  the  chaotic  hypoth- 
esis, both  as  originally  held  by  Werner,  and  modified  by 
intervention  of  internal  heat,  as  taught  by  De  la  Beche 
and  by  Daubr^e,  constituting  what  we  may  call  the  ther- 
MOCHAOTic  hypothesis.  It  remains  to  notice  first  the  two 
plutonic  hypotheses  just  named,  and  finally  to  consider 
the  metasomatic  hypothesis,  both  as  applied  to  rocks  con- 
sisting of  crystallir  j  silicates,  and  to  limestones. 

§  21.  Reasoning,  as  Naumann  has  said,  from  "the 
great  resemblance  which  gneiss  and  most  of  the  rocks  ac- 
companying it  bear  to  granite  and  to  other  eruptive  rocks ; 
the  probability  that  most  of  these  eruptive  rocks  have 
been  solidified  from  a  state  of  igneous  fluidity ;  the  almost 
unavoidable  assumption  that  our  planet  was  originally  in 
the  same  state,  and  was  only  later  covered  with  a  solidi- 
fied crust;  finally  the  fa  "t  that  in  the  primitive  gneissic 


irystal- 
revert 

ye  may 
sforma- 
its  into 

"Lehr- 
ing  the 
jrstalline 
nt  all  fa- 
arried  to 
IS  denied 
allization 
or  which 
call  their 

lay  those 
nigin,  the 
1  we  may 
t  by  those 
[ic  or  VOL- 


VO 


THE  ORIGIN   OP  CRYSTALLINE  ROCKS. 


85 


series,  granite  and  gneiss  are  found  regularly  interstrati- 
fied  with  each  other,"  we  are  led  to  what  we  have  desig- 
nated the  endoplutonic  hypothesis,  which  is,  that  the 
primitive  rocks  form  the  "first  solidified  crust  of  our 
planet."  Naumann  remarks  of  this,  that  although  it  has 
"  not  found  so  many  supporters  as  that  of  the  metamor- 
phic  origin  of  the  primitive  rocks,  the  objections  against 
it  are  probably  neither  greater  nor  more  numerous  than 
against  the  latter."  Of  this  hypothesis,  he  adds  that  "  it 
leads  necessarily  to  the  inference  that  the  succession  of 
the  primitive  rooks  downward  corresponds  to  their  age 
from  oldest  to  youngest,  because  it  was,  of  course,  through 
a  solidification  from  without  inward  that  the  strata  in 
question  were  formed."  Those  who  would  maintain,  on 
the  contrary,  that  the  succession  of  these  in  age  is  from 
below  upward,  must  suppose,  as  he  explains,  that  the  ma- 
terial of  the  younger  crystalline  rocks  "has  been  pro- 
truded from  the  interior,  through  the  earth's  crust,  in  an 
eruptive  form."  For  these  two  opposite  modes  of  forma- 
tion, both  essentially  plutonic,  we  may  properly  adopt  the 
names  of  '  endoplutonic,'  already  used  above,  to  designate 
the  hypothesis  which  supposes  the  rocks  to  be  generated 
within  tl.cj  first-formed  crust;  and  'exoplutonic'  for  that 
which  conceives  them  to  have  been  formed  outside  of  the 
same  crust,  by  eruptive  or  what  are  popularly  called  vol- 
canic processes. 

§  22.  The  endoplutonic  hypothesis  has  not  wanted  de- 
fenders, among  whom  are  some  of  the  most  distinguished 
names  of  geology,  lu  1882,  we  find  Hubert,  the  emi- 
nent professor  at  the  Sorbonne,  declaring  of  the  ancient 
crystalline  schists :  "  These  mineral  masses  appear  to  be 
due  to  a  crystallization  in  plc^e,  consequent  upon  the 
cooling  of  the  fluid  terrestrial  globe."  "  The  absence  from 
these  of  rolled  masses  or  of  detritus  of  pre-existing  rocks" 
—  assumed  by  him  —  "  indicates  that  water  did  not  at  that 
time  as  yet  exist  in  the  state  of  a  liquid  mass."  This 
series,  including  various  jji^eisses,  micaceous,  hornblendic 


■'".I ", 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


[V. 


and  chloritic  schists,  with  crystalliue  limestones,  "  should 
form  a  group  clearly  distinct  from  all  others.  It  is  ante- 
rior to  granite,  and  constitutes  a  truly  primitive  series, 
which  is  neither  eruptive  nor  sedimentary,  but  is  due  to  a 
third  mode  of  formation,  which,  borrowing  the  name  from 
d'Umalius  d'Halloy,  we  may  call  crystallophylliany  *  It 
is  difficult  to  conceive  that  this  can  be  any  other  than  that 
imagined  by  Naumann,  which  we  have  called  endoplu- 
tonic. 

§  23.  Thomas  Macfarlane,  in  a  learned  essay  in  1864, 
on  "  The  Origin  of  Eruptive  and  Primary  Kocks,"  f  has 
developed  the  hypothesis  of  the  endoplutonic  origin  of  the 
primitive  rocks  with  much  ingenuity,  and  defends  a  view 
already  suggested  by  Scheerer,  that  the  laminated  struc- 
ture of  these  rocks  may  have  been  caused  by  currents  in 
the  molten  mass  of  the  globe.  He  further  suggests  that 
the  first-formed  crust  may  have  had  a  different  rate  of 
rotation  from  the  liquid  below ;  J  from  which  also  would 
result  a  stratiform  arrangement  in  the  elements  of  the 
solidifying  layer,  such  as  is  seen  in  many  slags,  and  in 
certain  eruptive  rocks.  But  while  he  applies  this  view  to 
the  primitive  rocks,  he  proposes  for  the  later  crystalline 
schists  one  which  is  essentially  the  thermochaotic  hypoth- 
esis of  De  la  Beche  and  Daubrde,  ascribing  their  origin  to 
the  action  of  a  highly  heated  primeval  ocean  on  the  previ- 
ously formed  crust.  The  chief  difficulties  with  V'^hich 
this  endoplutonic  hypothesis  has  to  contend,  according  i.j 
Naumann,  "arise  from  the  structural  relations  of  the 
primitive  series,  and  the  mineralogical  characters  of  c^r- 

*  Bull,  Soc.  Ge'ol.  de  Francft  (3),  xi.,  30. 

t  Canadian  Natuialist,  vol.  viii. 

X  It  is  worthy  of  note  in  this  connection  that  Halley  was  long  ago  led, 
from  the  study  of  terrestrial  magnetism,  to  adopt  a  similar  hypothesis 
with  re^/ard  to  the  earth's  interior.  "He  supposed  the  existence  of  two 
magnetic  poles  situated  in  the  earth's  outer  crunt,  and  two  others  in  an 
interior  mass,  separated  from  the  solid  envelope  by  a  fluid  medium,  and 
revolving  by  a  very  small  degree  slower  than  the  outer  crust.  The  same 
conclusion  was  subsequently  adopted  by  Ilansteen."  (Hunt,  Chem.  and 
Geol.  Essays,  p.  60.) 


v.i 


TFm  ORIGIN   OF   CRYSTALLINE   ROCKS. 


87 


ould 
aiite- 
eries, 
J  to  a 
from 
*    It 
a.  that 
ioplu- 

1864, 
'I  has 
of  the 
a  view 
1  struc- 
ents  in 
3ts  that 
rate  of 
0  would 
,  of  the 

and  in 
view  to 
ystalline 
!  hypoth- 
origin  to 
he  previ- 
;li  w'hich 
Drding  ■«-J 
,s  of  the 
rs  of  cer- 


tain rocks  belonging  to  it.  Whether  these  difficulties  can 
be  explained  away  by  the  supposition  of  a  hydro-pyrogen- 
ous  development  of  the  outside  of  the  first  solidified  crust, 
as  indicated  by  Angelot,  Rozet,  Fournet,  Scheever,  and 
others,  we  must  leave  undecided  in  the  meantime."  Such 
a  hyclro-pyrogenous  process  is  more  clearly  defined  by 
Daubr^e,  when  he  refers  the  formation  of  granites  and 
crystalline  schists  "  to  aqueous  action  intervening  under 
extreme  conditions  which  approach  igneous  action,"  as 
explained  in  §  14.  Any  modificati  ms  of  the  heated  crust 
through  the  intervention  of  water  must  come  under  the 
categories  of  what  we  have  called  the  thermochaotic  and 
the  metasomatic  hvpotheses,  or  else  of  that  one  which 
remains  to  be  described  in  the  present  essay. 

§  24.  In  the  paper  already  cited,  Macfarlane  has,  more- 
over, discussed  at  length  the  probable  condition  of  the 
earth's  interior,  beneath  the  crust  of  primitive  straiiform 
rocks,  with  especial  reference  to  the  origin  of  the  different 
types  of  eruptive  rocks.  Already  in  the  last  century  we 
find  Dolomieu  maintaining  the  existence,  beneath  the 
granitic  substratum,  of  a  liquid  layer  fiom  which  come 
what  he  called  basaltic  lava-flows.  A  similar  view  was 
developed  later  by  Phillips,  Durocher,  Bunsen,  and 
Streng,  who  have  imagined  a  separation  of  the  liquid 
matter  at  the  surface  of  the  cooling  globe  into  two  layers, 
an  upper,  acidic  one,  corresponding  to  granites  and  tra- 
chytes, in  which,  besides  alumina  and  an  excess  of  silica, 
lime,  magnesia,  and  iron-oxyd  are  present  in  very  small 
quantities,  and  potash  and  soda  abound;  and  a  lower, 
basic  one,  corresponding  to  dolerite  and  basalt,  in  which 
lime,  magnesia,  and  iron-oxyd  abound,  with  an  excess  of 
alumina,  and  but  little  alkali.  These  two  constitute  the 
trachytic  and  pyroxenic  magmas  of  Bunsen,  who  endeav- 
ored to  determine  what  he  conceived  to  be  their  normal 
composition,  and,  as  is  well  known,  sought  to  show  that 
there  exists  such  a  relation  between  the  proportions  of 
these  various  bases  and  the  silica,  that  it  is  possible  to 


ijiimiiSili 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


[V. 


y    ' '  'i.  1 


calculate  the  composition  of  any  given  eruptive  rock  from 
the  amount  of  this  element  which  it  contains.  He  thence 
concluded  that  various  intermediate  rocks  have  been 
produced  by  a  mingling  or  amalgamation,  in  different 
proportions,  of  these  two  separated  magmas.  For  the 
composition  of  these,  see  farther  a  note  to  §  6Q.  I  have 
elsewhere  discussed  the  history  of  this  hypothesis,  and 
have  given  reasons  for  its  rejection.* 

Sartorius  von  Waltershausen  has  also  objected,  from 
another  point  of  view,  to  this  hypothesis,  and  has  main- 
tained that  while  there  is  no  such  distinct  separation  of 
the  liquid  interior  as  was  imagined  by  Phillips,  Durocher, 
and  Bunsen,  there  is  nevertheless  a  gradual  passage  down- 
ward from  a  lighter,  acidic  to  a  denser  and  more  basic 
liquid  stratum ;  beneath  which  still  heavier  metallic  min- 
erals are  supposed  by  him  to  be  arranged  in  the  order  of 
their  respective  densities.  This  view  has  been  adopted 
and  extended  by  Mr.  Macfarlane  in  his  paper  above  cited. 
We  shall  however  attempt  to  show  in  the  second  part  of 
this  memoir  that  the  observed  relations  of  acidic  and  basic 
eruptive  rocks  admit  of  a  widely  different  interpretation 
to  those  above  given,  and  one  more  in  accordance  with 
known  chemical  and  mineralogical  facts.f 

§  25.  Returning  from  this  digression  on  hypothetical 
notions  of  the  earth's  interior,  we  propose  to  consider  the 
exoplutonic  or  volcanic  hypothesis  of  the  origin  of  the 
crystalline  stratified  rocks,-  accoi*ding  to  v/hich,  as  con- 
cisely stated  by  Naumann,  the  material  composing  them 
"  has  been  projected  from  the  interior,  through  the  earth's 
crust,  in  an  eruptive  form."  Inasmuch  as  the  matter  dis- 
charged in  sub-aerial  or  submarine  eruptions  appears  in 
part  as  flows  of  molten  lava,  and  in  part  as  disintegrated 

*  On  the  Probsble  Seat  of  Volcanic  Action,  Geological  Magazine, 
June,  1860,  and  Chem.  and  Geol.  Essays,  p.  66. 

t  For  a  discussion  of  the  views  of  Phillips,  Lorocher,  Bunsen,  and 
Streng,  see  Hunt,  Chem.  and  Geol.  Essays,  pp.  3-6,  66,  and  284.  See 
also  farther  Bunsen,  Ann.  de  Chim.  et  de  Phys.,  1853  (3),  vol.  xxxviii., 
pp.  215-289. 


v.] 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


89 


solid  materials  which,  like  other  detritus,  may  be  arranged 
by  water,  it  is  evident  that  this  hypothesis  connects  itself 
with  that  of  the  Huttonian  school,  to  which,  considering 
the  mineralogical  resemblances  between  volcanic  and  other 
crystalline  rocks,  it  would  make  little  difference  whether 
the  sediments  required  for  the  metamorphic  process  came 
from  the  disintegration  of  older  crystalline  strata,  from  a 
primeval  granite,  or  from  volcanic  products.  The  vol- 
canic hypothesis,  except  so  far  as  consolidated  lava-flows 
are  concerned,  thus  becomes,  as  we  shall  see,  a  metamor- 
phic or  plutonic-detrital  hypothesis. 

As  an  illustration  of  this  view,  we  find  J.  D.  Dana  in 
1843  propounding  a  general  theory  of  crystalline  rocks, 
which  is  essentially  volcanic.  In  this  he  endeavors  to 
show  (1)  that  the  schistoiie  structure  of  gneiss  and  mica- 
schist  is  not  a  satisfactory  evidence  of  sedimentary  origin, 
inasmuch  as  exotic  or  eruptive  rocks  may  sometimes  take 
on  a  laminated  arrangement;  (2)  that  granites  without 
any  trace  of  schistose  structure  may  have  had  a  sedimen- 
tary origin ;  and  (3)  that  the  heat  producing  metamorphic 
changes  in  sediments  did  not  come  from  below,  as  sup- 
posed by  the  Huttonians,  but  through  the  waters  of  the 
ocean,  heated  by  the  same  eruption  which  brought  to  the 
surface  the  materials  of  the  metamorphic  rocks,  which 
were  spread*  over  the  ocean's  bottom  in  a  disintegrated 
form.  Their  comminution  was  supposed  by  Dana  to  be 
effected  in  one  of  three  ways :  (1)  they  were  ejected  as 
pyroclastic  material,  in  the  form  of  a  sand  or  ash-eruption, 
or  (2)  were  disintegrated  by  coming  in  contact  with  water 
while  in  a  fused  condition,  or  (3)  were  broken  by  abrasion 
after  consolidation.  In  any  case,  the  detrital  matter,  as  in 
the  Huttonian  hypothesis,  was  supposed  to  be  trr  isformed 
into  a  crystalline  rock  by  the  action  of  heated  \»aters. 

§  26.  After  assigning  such  an  origin  to  certain  rocks 
called  by  him  metamorphic  porphyries  and  basalts,  with 
regard  to  which  he  supposes  "  every  eruption  produced  a 
heated  sea  around  it,  which  hardened  "  the  disintegrated 


90 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


[V. 


porphyry,  and  recrystallized  the  comminuted  materials, 
Dana  proceeds  to  say  that  "  granite,  like  porphyry,  is  an 
igneom  rock.  In  its  era,  granite-sands  were  formed  like 
porphyry-sands,  and  restored  by  heat  to  metamorphic 
granite,  like  metamorphic  porphyry.  ...  I  use  the  word 
granite  here  as  a  general  term  for  this  and  the  associated 
rocks,  mica-slate,  syenite,  and  hornblende-slate,  etc.,  which, 
I  have  shown,  may  also  have  an  igneous  origin.  These 
granite-sands,  like  porphyry-sands,  were  formed  about  the 
regions  of  eruption,  in  one  of  the  modes  pointed  out, 
and  in  all  probability  were  never  clays  like  the  alluvial 

deposits  of  the  present  day With  regard  to  primary 

limestones,  a  general  survey  of  the  facts  seems  to  evince 
that  some  of  these  were  of  igneous  origin  like  granite. 
If  this  were  the  case,  there  must  have  been  others,  formed 
at  the  same  time  with  the  deposits  of  granite-sand,  and 
through  the  action  of  the  same  causes.  These  were  re- 
crystallized  by  the  next  discharge  of  heated  waters."  * 
Dana,  forgetting  the  effects  of  the  law  of  convection  ia 
liquids,  here  makes  the  suggestion  that  "at  no  great 
depth  the  waters  might  be  raised  to  the  heat  of  ignition 
before  ebullition  will  begin,  and  if  the  leaden  waters  of  a 
deep  ocean  .  .  .  are  for  days  in  contact  with  the  open 
fires  of  submarine  volcanoes,  we  can  scarcely  fix  a  limit, 
to  the  temperature  which  they  would  necessarily  receive." 
We  have  thus  presented  a  complete  exoplutonic  or  vol- 
canic hypothesis,  and  at  the  same  time  a  complete'  meta- 
morphic or  volcanic-detrital  hypothesis,  alike  for  porphyry, 
granite,  syenite,  gneiss,  mica-schist,  and  crystalline  lime- 
stone ;  each  and  all  which  are  assumed  to  have  a  twofold 
origin,  and  to  appear  alike  in  an  eruptive  and  in  a  second- 
ary sedimentary  form.  A  reference  to  the  previous  specu- 
lations of  Scrope,  already  set  forth  in  §  17,  will  show  to 
what  extent  Dana  was  his  disciple. 

*  Dana,  On  the  Analogies  between  the  Modem  Igneous  Rocks  and  the 
so-called  Primary  Formations.  Amer.  Jour.  Science,  1843,  vol.  xlv.,  pp. 
104-129. 


v.i 


THE  ORIGIN  OF  CRYSTALLINE  ROOKS. 


91 


§  27.  Dana  has  since  abandoned  this  hypothesis,  so  far 
as  regards  the  eruptive  origin  of  the  detrital  matters.  In 
his  later  writings,  he  sets  forth  the  familiar  view  of  a 
liquid  interior  ccvered  with  a  solid  crust,  which  latter  was 
the  supposed  source  of  the  Archasan  or  primitive  rocks. 
"  These  Archaean  rocks  are  the  only  universal  formation  ; 
tliey  extend  over  the  whole  globe,  and  were  the  floor  of 
the  ocean,  and  the  material  of  all  the  emerged  land,  when 
life  first  began  to  exist."  These  rocks  of  the  first  crust, 
disintegrated  by  submarine  and  sub-aerial  agencies,  yielded 
beds  of  detritus,  which,  being  consolidated  by  the  action 
of  the  heated  waters,  gave  rise  to  new  rocks,  which  would 
"be  much  like  those  that  resulted  from  the  original  cool- 
ing, because  chiefly  made  out  of  the  latter  by  reconsoli- 
dation  and  recrystallization."  "  Igneous  rocks  have  a 
close  resemblance  to  granite,  diorite,  and  other  crystalline 
kinds,  and  hence  may  have  proceeded  from  the  fusion  of 
older  kinds.  But  these  older  kind?  derived  their  material 
from  an  older  source,  and  originally  from  the  fused  mate- 
rial of  the  globe,  so  that  the  proof  of  such  an  origin  by 
refusion  is  not  established  beyond  a  doubt." 

§  28.  It  is  not  clear  whether,  according  to  Dana, 
we  have  anywhere  this  hypothetical  primitive  or  truly 
Archaean  rock  exposed,  since,  speaking  of  the  Laurentian 
series,  which  he  also  calls  Archaean,  he  says  at  the  same 
time  :  — "  These  Laurentian  rocks  are  made  out  of  the 
ruins  of  older  Laurentian,  or  of  still  older  Archaean 
rocks ;  that  is  to  say,  the  sands,  clays,  and  stones  made 
and  distributed  by  the  ocean,  as  it  washed  over  the 
earliest-formed  crust  of  the  globe.  The  loose  material, 
transported  by  the  currents  and  the  waves,  was  piled  into 
layers,  as  in  the  following  ages,  and  vast  accumulations 
were  formed ;  for  no  one  estimates  the  thickness  of  the 
recognized  Laurentian  beds  as  below  thirty  thousand 
feet."  Lest  he  should  be  supposed  to  hold  to  his  former 
theory  of  the  volcanic  origin  of  these  supposed  detrital 
matters,  which  formed  the  Laurentian,  he  now  declares, 


02 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


IV. 


"They  have  no  resemblance  to  lavas  or  igneous  ejec- 
tions." *  These  crystalline  stratified  rocks  are  thus  not 
that  universal  Archtean  terrane  which  was  the  first-formed 
crust  of  the  cooling  globe.  The  imagination  is  at  a  loss, 
however,  to  understand  the  nature  of  the  disintegrating 
process,  or  the  source  of  the  materials  wliich  in  the  Lau- 
rentian  period  were,  according  to  this  hypothesis,  spread 
over  vast  areas  to  a  depth  of  not  less  than  thirty  thou- 
sand feet,  and  seeks  in  vain  for  the  site  of  the  vanished 
Atlantis  which  furnished  this  enormous  amount  of  me- 
chanically disintegrated  rock. 

§  29.  Clarence  King,  in  1878,  gave  us  a  clear  and 
admirable  discussion  of  the  same  detrital  metamorphic 
theory,  and  argued,  as  Dana  had  done  before  him,  that 
the  depression  of  sedimentary  strata  below  the  surface  of 
the  earth,  even  to  gieat  depths,  is  not  sufficient  to  effect 
their  crystallization;  since  basal  paleozoic  beds  which 
have  been  buried  beneath  30,000  feet  or  more  of  sedi- 
ments are  now  seen,  when  exposed  by  great  movements 
of  elevation,  and  by  erosion,  to  present  no  evidences  of 
crystallization  or  so-called  alteration.  King,  however, 
did  not  reject  volcanic  action  as  a  source  of  detritus,  for 
in  discussing  the  origin  of  the  great  beds  of  serpentine 
and  of  olivine-rock  which  are  often  met  with  in  the  older 
crystalline  schi^.ts,  he  says,  "  olivine-bearing  rocks  are 
among  the  oldest  eruptive  bodies,"  and  then  asks,  "  may 
not  olivine-sands,  like  those  now  seen  on  the  shores  of 
the  Hawaiian  Islands,  have  been  then,  as  now,  accumu- 
lated by  the  mechanical  separation  of  sea-currents,  and 
subsequently  buried  by  feldspathic  and  quartz-sands." 
He  thus  looks  to  volcanic  eruptions  for  the  source  of 
olivine  and  serpentine  beds,  and  adds,  "I  see  no  reason  to 
ask  for  a  different  origin  for  the  magnesian  silicates  than 
for  the  aluminous  minerals,"  f  the  eruptive  source  of 
which  is  thus  implied.      A  similar  hypothesis  of  the  for- 

*  Dana,  Manual  of  Geology,  3rd.  ed.,  1879,  pp.  147,  154,  155,  also  720. 
t  Geology  of  the  Fortieth  Parallel,  vol.  i.,  p.  117. 


▼J 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


93 


mation  of  beds  of  olivine-rock  and  serpentine  from 
accumulations  of  volcanic  olivine-sand,  has  since  been 
maintained  by  Julien,  whose  paper  is  mentioned  further 
on,  §  37. 

§  30.  Other  geologists,  besides  King,  have  in  later 
times  advocated  a  similar  volcanic  hypothesis  of  the 
origin  of  crystalline  rocks.  A.  Kopp,  in  1872,  taught 
that  granite  is  an  altered  trach^tic  lava,  and  that  gneiss 
may  be  derived  from  the  detritus  of  trachyte  or  of  gran- 
ite, while  doleritic  lavas  in  like  manner  give  rise  to  the 
various  greenstones.  The  transformation  of  these  is  sup- 
posed to  be  effected  through  the  intervention  of  heated 
waters,  at  great  depths  in  the  earth.*  All  this  is  but  a 
repetition  of  the  hypothesis  put  forward  forty  years  sinca 
by  Dana,  and  subsequently  abandoned  by  him. 

Tornebohm  has  also  lately  advanced  a  similar  hypothe- 
sis to  explain  the  origin  of  the  primitive  granite,  and  of 
the  gneiss  into  which  it  seems  to  graduate.  The  material 
of  these  rocks  came  up  as  lava  now  does,  and  a  portion  of 
it,  disintegrated,  re-arranged  by  water  and  recrystallized, 
assumed  the  form  of  gneiss.  Reusch,  in  like  manner,  ac- 
cording to  Marr,  supposes  that  the  gabbros,  diorites,  and 
dioritic  and  hornblendic  schists  of  the  Bergen  district,  in 
Norway,  are  but  altered  tufas  and  erupted  rocks. 

§  31.  Mr.  Marr,  in  a  recent  paper,  urges  the  claims 
of  the  volcanic  hypothesis  to  explain  the  origin  of  the 
ancient  crystalline  rocks,  seemingly  unaware  of  its  earlier 
advocates.  It  is  apparent  that  if  we  accept  the  doctrine 
of  the  permanence  of  continents  and  of  oceanic  depres- 
sions, the  metamorphic-detrital  theory  of  the  Huttonians, 
which  builds  up  series  of  crystalline  rocks  beneath  the 
sea  from  the  ruins  of  an  older  land,  which  had  itself  been 
formed  beneath  the  sea,  is  no  longer  tenable.  The  diffi- 
culty of  getting  the  thirty  thousand  feet  of  sediments 
required  to  spread  over  a  continent,  as  in  Dana's  later 
hypothesis,  is,  as  Marr  perceives,  overcome  if  we  suppose 
«  Neues  Jahrbuch  fiir  Mineralogie,  1872,  pp.  388  and  490. 


11 


|:    I.I 

I 


\h  U.I 


m 
'.1.1  f 


1*1 


If; 


K^ 


94 


THE  ORIGIN  OF  CRYSTALLINB  ROCKS. 


w 


this  material  to  have  been  derived,  not  by  the  superficial 
waste  and  disintegration  of  former  land,  but  by  ejection 
from  reservoirs  beneath  the  earth's  crust.  Hence,  with 
the  advocates  of  the  doctrine  of  the  permanence  of  conti- 
nents, the  volcanic  or  exoplutonic  hypothesis  is  again  com- 
ing into  favor.* 

Similar  considerations  appear  to  have  led  C.  H.  Hitch- 
cock, in  1883,  to  a  like  conclusion.  The' continents,  in  his 
scheme,  are  built  up  from  beneath  the  waters  of  a  univer- 
sal ocean.  He  writes :  —  "  We  start  with  the  earth  in  the 
condition  of  igneous  fluidity.  It  cools  so  as  to  become 
encrusted  and  covered  with  an  ocean.  Numerous  volca- 
noes discharge  molten  rock,  building  up  ovoidal  piles  of 
granite  [beneath  the  ocean],  which  change  gradually  into 
crystalline  schists.  When  the  hills  are  high  enough  to 
overlook  the  water,  they  constitute  the  beginnings  of  dry 
land."  This  is  intelligible,  but  it  seems  strange  to  one 
familiar  with  the  geological  literature  of  the  last  forty 
years  to  read,  in  this  connection,  the  remark  of  Hitchcock 
that  few  "have  ventured  to  spp"k  of  anything  like  vol- 
canic action,  except  as  it  has  been  manifested  in  the  for- 
mation of  dikes,  in  the  early  periods."  f 

To  all  of  these  speculations  as  to  the  exoplutonic  or 
volcanic  origin  of  the  crystalline  rocks,  the  language  of 
Naumann,  in  criticising  the  original  volcanic  hypothesis 
of  Dana,  is  applicable.  "The  perfect  and  thoroughly 
crystalline  character  of  the  gneiss,  the  enormous  extent 
which  the  primitive  formations  occupy  in  so  many  dis- 
tricts, the  architecture  of  these  great  gneissic  regions,  and 
their  occurrence  wholly  independent  of  larger  granitic 
masses,  are  all  incompatible  with  this  idea." 

§  32.  The  view  of  the  igneous  and  eruptive  origin  of 
crystalline  limestone,  admitted  in  Dana's  former  scheme, 
was  familiar  to  the  geologists  of  forty  years  since.    Em- 

*  Marr,  The  Origin  of  Archisan  Rocks;  Geological  Magazine,  June, 
1883. 

t  Hitchcock,  The  Early  History  of  the  North  American  Continent.  — 
Proc.  Amer.  Assoc.  Adv.  Science,  1883. 


v.i 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


u 


mons  and  Mather  in  America,  and  Von  Leoiihard,  Rozet, 
and  Savi  in  Europe,  among  others,  then  lieUl  to  the  belief 
that  many  crystalline  limestones  were  igneous,  and  Savi 
had  even  attempted  to  point  out  the  centres  of  eruption 
of  the  Carrara  marbles.*  It  is  hardly  necessary  to  recall 
the  fact  that  serpentines,  and  great  deposits  of  magnetite 
and  specular  iron,  are  still  by  some  authorities  considered 
as  eruptive  rocks,  and  that  the  hypothesis  of  the  igneous 
origin  of  metalliferous  lodes,  taught  by  Hutton,  is  not  yet 
wholly  obsolete.  In  1858,  H.  D.  Rogers  wrote  of  "the 
great  dikes  and  veins  of  auriferous  quartz  "  supposed  to 
have  issued  "  in  a  melted  condition,  through  rents  and  fis- 
sures in  the  earth's  crust.  Outgushing  bodies  of  this 
quartz,"  chilled  by  contact  with  the  cold  waters  of  the 
ocean,  were  supposed  by  him  to  have  furnished  the  mate- 
rial for  the  Primal  quartzites  of  Pennsylvania.f  Still 
later,  in  1874,  we  find  Belt  raaintahiing  with  learned  in- 
genuity the  igneous  origin  and  the  injection  of  auriferous 
quartz  veins.  He  insists,  as  I  have  elsewhere  done,|  on 
the  transition  from  veins  of  quartz,  often  metalliferous,  to 
others  containing  feldspar,  and  thence  to  true  granitic 
veins ;  but  instead  of  regarding  these  as  aqueous  and  con- 
cretionary, assumes  them  to  be  igneous,  and  thence  con- 
cludes that  the  gold-bearing  quartz  lodes  were  filled  with 
liquid  quartz  by  "  igneous  injection,"  though  admitting 
that  in  these,  as  in  granites,  water  helped  to  impart 
liquidity.  § 

§  33.  In  farther  illustration  of  the  extension  of  the 
plutonic  doctrine  to  other  rock-masses  than  those  already 
mentioned,  I  quote  from  an  essay  by  Daubr^e,  published 

*  See  for  references,  Hunt,  Chem.  and  Geol.  Essays,  p.  218;  also  Boue, 
Guide  du  G^ologue  Voyageur,  ii.,  108. 

t  Geology  of  Pennsylvania,  ii.,  780. 

t  Chemical  and  Geological  Essays,  pp.  192-208,  and  infra  §  58. 

§  Belt,  The  Naturalist  in  Nicaragua,  1874,  pp.  97-100.  In  the  pages 
here  referred  to,  my  friend,  whose  premature  death  was  a  great  loss  to 
science,  has  set  forth  with  clearness  the  Huttonian  theory  of  metallifer- 
ous veins. 


THE  OlllGIN   OF  CRYSTALLINE  UOCICS. 


IV. 


in  1871.*  "The  hypothesis  advanced  by  Lazzaro  Moro, 
in  1740,  attributing  an  eruptive  origin  to  rock-salt,  as  well 
as  to  uulpluir  and  bitumen,  was  again  tal^on  up  and  applied 
by  De  Cliarp'intier  (1823)  to  the  salt-mass  at  Hex,  whicli 
is  associated  with  anhydrite  ;  and  D'Alburti,  in  the  chissic 
study  made  by  him  of  this  terrano,  maintained  the  same 
hypothesis  for  all  the  rock-salt  found  in  the  trias.  More- 
over, the  examination  of  the  deposits  of  pisolitic  iron-ore 
had,  in  1828,  conducted  Alexandre  Brongniart  to  a  similar 
conclusion,  which  was  soon  after  applied  to  the  siliceous 
deposits  which  constitute  the  buhrstone  of  the  tertiary. 
A  like  origin  was  by  D'Omalius  (1841  and  1855)  ascribed 
to  other  substances,  particularly  to  certain  clays  and  to 
certain  sands,  which,  especially  in  Belgium,  appear  to  be 
connected  with  the  formation  of  calamine,  and  which  Du- 
mont  in  1854  called  geys^rian  deposits."  " It  was  thus," 
adds  Daubr<je,  "  that  various  substances  belonging  to  sedi- 
mentary strata  were  recognized  as  coming,  or  at  least  were 
supposed  to  come,  from  the  lower  regions  (^Staient  re- 
oonnues,  on  au  moins  Staient  supposSes,  provenir  dea  regions 
profondes),''^ 

§  34.  The  presence  of  water  in  ignited  and  molten 
rocks  was  shown  by  Poulett  Scrope  in  1825,  in  his  studies 
of  volcanoes,  f  Subsequently,  Scheerer  conceived  that  a 
small  portion  of  water,  probably  five  or  ten  hundredths, 
might,  at  a  low  red  heat,  give  rise  to  a  condition  of  imper- 
fect liquidity  such  as  he  imagined  for  the  material  of 
eruptive  granites.  Similar  ideas  as  to  the  aqueo-igneous 
fusion  of  granite  were  at  the  same  time  adopted  by  Elie 
de  Beaumont,  and  are  now  generally  admitted,  the  more 
so  as  they  are  in  accordance  with  the  results  of  micro- 
scopic study.  From  the  presence  in  granitic  rocks  of 
what  he  called  pyrognomic  minerals,  like  allanite  and 

•  Daubr<5e,  Des  terrains  stratlfids  consld^r^s  au  point  de  vue  de  I'ori- 
gine  des  substances  qui  les  constituent,  etc.  Bull.  Soc.  Geol.  de  France 
(2),  xxviii.,  p.  307. 

t  Scrope,  Considerations  on  Volcanoes,  p.  25. 


v.i 


THE  ORIOIN  OP  CRYSTALLINE  ROCKS. 


97 


gadoliiiite,  whicli,  by  exposure  to  ignition,  unclorgo  phy- 
sical and  chemical  changes,  Scheerer,  moreover,  argued 
that  the  temperature  of  formation  of  the  granitic  veins 
liolding  these  minerals  could  not  have  boon  very  high.* 

This  notion  of  hydroplutonic  eruptions,  thus  set  forth 
by  Scrope,  Scheerer,  and  filie  do  Beaumont,  has  received  a 
still  further  extension  of  late.  The  hydratcd  rock,  serpen- 
tine, is  supposed  by  some  of  those  who  nuiintain  its  exo- 
plutonic  derivation  to  have  come  up  from  below  as  an 
anhydrous  silicate,  and  to  liave  been  subsecjuently  liy- 
drated.  Daubrde,  however,  has  suggested  that  it  had 
already  passed  into  the  hydrated  condition  before  its  ejec- 
tion.! Akin  to  this  is  the  view  of  some  modern  Italian 
geologists,  who  explain  the  stratiform  character  of  this 
rock  by  supposing  that  it  was  ejected  from  below  as  an 
aqueous  magma,  chiefly  of  hydrated  silicates  of  magnesia 
and  iron,  mingled  in  some  cases  with  feldspathic  matter, 
from  which,  by  crystallization  and  re-arrangement,  the 
masses  of  serpentine  and  their  associated  euphotides  have 
been  formed,  as  well  as  the  accompanying  anhydrous  sili- 
cates, olivine  and  enstatite.  By  this  hypothesis  "  the 
serpentines  are  considered  as  eruptive  without  being  truly 
igneous,  inasmuch  as  they  do  not  contain  in  their  compo- 
sition any  mineral  which  has  been  submitted  to  igneous 
fusion,"  though  "the  magma  may  have  had  a  temperature 
of  several  hundred  degrees."  | 

The  conception  of  hydroplutonic  eruptions,  whether  ap- 
plied by  Scrope  to  lavas,  by  Scheerer  to  granites,  by  Belt  to 
metalliferous  quartz  lodes,  or  by  Daubrce  and  some  Italian 
geologists  to  serpentines  and  euphotides,  is  instructive  as 
a  phase  in  the  development  of  that  geological  hypothesis 

*  For  an  analysis  of  these  views  of  Scliperer  and  Elle  de  Beaumont, 
and  references  to  the  controversies  to  wliich  they  gave  rise,  see  Hunt, 
Chemical  and  Geological  Essays,  pp.  5,  6,  and  188,  189. 

t  Gdologie  Experimentale,  p.  642. 

t  See,  for  an  account  of  this  hypothesis  as  maintained  by  Issel  and 
Capacci,  with  much  deUil  in  their  studies  of  Italian  Serpentines,  Essay 
X.,§  90-03. 


Icii.-i  ;i  I'M 


Sll^llillit 


98 


THE  ORIGIN   OP  CRYSTALLINE  ROCKS. 


[V- 


according  to  which  a  volcano  is  a  deus  ex  machina,  to  be 
invoked  for  the  solution  of  every  knotty  problem  that 
presents  itself  in  studying  the  origin  of  rock-masses. 

§  35.  Writing  in  1883  of  the  extravagances  of  the  exo- 
plutonic  or  volcanic  doctrine,  I  spoke  of  it  as  "tlie  belief 
in  a  subterranean  providence  which  could  send  forth  at 
will  from  its  reservoirs  "  alike  granite  and  basalt,  olivine- 
rock  and  limestone,  quartz-rock  and  magnetite.  *  An 
otlierwise  friendly  critic f  speaks  of  this  language  as  "a 
kind  of  device  for  producing  a  false  impression,  by  asso- 
ciating rucks  for  the  most  part  of  eruptive  origin  with 
others  which  are  not  so."  This,  however,  is  precisely 
what  the  plutonic  school  in  question  has  done,  and  is  still 
doing.  Eminent  teachers  ir  geology  of  our  time,  some  of 
them  still  living,  have,  as  we  have  here  shown,  included 
with  granites  and  basalt,  not  only  serpentines,  but  lime- 
stones, magnetite,  auriferous  quartz,  buhrstone,  rock-salt, 
anhydrite,  liydrous  iron-ores,  and  even  certain  clays  and 
sands,  among  the  substances  which  have  been  thrown  up 
from  the  depths  of  the  earth. 

The  obvious  question,  as  to  the  origin  of  these  supposed 
accumulations  of  various  and  unlike  substances  in  the 
underworld,  has  been  one  to  perplex  the  thoughtful  geol- 
ogists of  this  school,  and  for  those  who  did  not  admit  that 
such  might  come  from  buried  deposits,  once  superficial, 
presented  difficulties  which  it  was  sought  to  overcome  by 
a  general  theory  of  transmutation  ;  by  which  it  was  imag- 
ined that  a  part  or  the  whole  of  the  original  elements  of  a 
rock  might  be  replaced,  thus  giving  rise  to  new  lithologi- 
cal  species.  Such  a  change  has  been  appropriately  named 
a  metasomatosis  or  change  of  body.  I  have  elsewhere 
pointed  out  that  this  view  has  been  adopted  by  two  dis- 
tinct and,  to  a  certain  extent,  opposed  schools  in  geology, 
both  of  which,  however,  agree  in  admitting  an  almost  un- 
limited capacity  of  change  of  substance,  through  aqueous 

*  Ibid.,  vol.  i.,  part  Iv.,  p.  200. 

t  Geological  Magazine  for  June,  1884,  p.  278. 


v.i 


THE   OUIGIN   OF   CRYSTALLINE  ROCKS. 


99 


agencies,  in  previously  solidified  rocks.  The  first  of 
these  schools  applies  the  doctrine  of  metasoniatosis  to  sili- 
cated  and  aluminous  rocks,  either  of  plutonic  or  plutonie- 
detrital  origin ;  the  second  to  rocks  of  generally  acknowl- 
edged aqueous  origin,  such  as  limestones.* 

§  36.  As  regards  the  metasoniatosis  of  plutonic  or  plu- 
tonic-detrital  rocks,  such  as  the  ordinary  feldspathic  types, 
—  granites,  gneisses,  diabases,  and  diorites, —  we  are 
taught  the  conversion  of  any  one  or  all  of  these  into  ser- 
pentine or  into  limestone.  The  integral  change  of  each 
one  of  these  into  serpentine  by  the  complete  elimination 
of  alumina,  alkalies,  and  lime,  and  the  replacement  of 
these  bases  by  magnesia  and  water,  has,  as  is  well  known, 
been  maintained  by  many  writers  of  repute,  including 
Miiller  and  Bischof,  and  later,  Dana  and  Delesse.  More- 
over, King  and  Rowney  have,  since  1874,  taught  the 
conversion  into  limestones  of  all  the  silicated  rocks  men- 
tioned, and  have  assigned  such  an  origin  to  the  great 
interstratified  masses  of  crystalline  limestone  which  are 
found  in  the  ancient  gneisses,  alike  of  North  America  and 
Europe.  Not  content  with  this,  they  have  even  main- 
tained the  conversion  of  serpentine  itself  into  limestone, 
and  have  explained  the  existence  of  ophicalcites,  and  of 
serpentine  masses  in  limestone,  as  evidences  of  the  incom- 
plete transformation  of  beds  of  serpentine,  itself  the 
product  of  a  previous  transformation  of  feldspathic  rocks. f 
The  older  school  of  metasomatists  regarded  serpentine 
and  other  hydrated  magnesian  silicates,  on  account  of 
their  insolubility,  as  the  last  term  in  the  metasomatic 
process;  but  King  and  Rowney  contend  that  serpentine 
itself  is  not  exempt  from  change. 

§  37.  Among  the  gneisses  and  mica-schists  of  the  Atlan- 

*  See,  in  this  connection.  Hunt,  Cliem.  and  Geol.  Essays,  pp.  31C,  320, 
325;  also  preface  to  *he  second  edition  of  the  same,  pp.  xxvii.-xxxi. ;  and 
fartlicr,  Essay  X.,§  10  and  §  108-110. 

t  Chem.  and  Geol.  Essays,  p.  324 ;  also  Trans.  Roy.  Soc.  Can. ,  I. ,  part . 
iv.,  p.  204;  and  W.  King  and  T.  IL  Rowney,  An  old  Chapter  of  the  Geo- 
logical Record,  1S81,  chaps,  vii.  and  xii. 


100 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


Vfi 


im 


I  im 


tic  belt  are  found  at  many  points,  especially  in  Pennsyl- 
vania, and  thence  southward  through  the  Carolinas  into 
Alabama,  important  masses  of  a  rock  composed  essentially 
of  chrysolite  oi  divine,  and  referred  to  dunite  or  Iherzo- 
lite.  With  these  are  associated  not  only  serpentine,  but 
various  hornblendic  and  feldspathic  rocks,  together  with 
much  corundum  —  the  latter  ahke  in  segregated  veins  and 
disseminated  in  the  beds.  These  chrysolite  roeks,  which, 
a ;  seen  in  North  Carolina,  were  already  described  by  the 
writer,  in  1879,  as  indigenous  stratified  deposits  in  the 
Montalban  series,*  have  been  made  the  subject  of  detailed 
studies  boih  by  Genth  and  by  Julien,  whose  published 
results  are  instructive  examples  of  the  application  of  the 
raetasomatic  doctrine  in  the  hands  of  its  disciples.  Genth 
supposes  that,  at  the  time  when  these  chrysolite  rocks 
were  deposited,  vast  amounts  of  alumina  were  set  free  by 
some  unexplained  process,  and  formed  beds  of  corundum, 
and  that  this  species,  by  subsequent  hydration  and  m?ta- 
scmatosis,  has  been  changed  to  bauxite,  diaspore,  spinel, 
opal,  and  a  great  number  of  aluminiferous  silicates,  includ- 
ing various  micas,  probably  some  feldspars,  ana  also  mag- 
nesian  silicates  of  the  chloritic  group.  The  final  result 
has  been,  "in  many  instances,  a  pretty  thorough  alteration 
of  the  original  corundum  into  micaceous  and  chloritic 
schists  or  beds,  or,  as  Prof.  Dana  would  express  it,  '  a  pseu- 
domorphism on  a  broad  scale.' "  f 

*  See  James  Macfarlane's  Geological  Handbook,  1879,  p.  130;  and,  for 
some  notes  on  the  history  of  similar  rocks,  Essay  X.,  §  123-125. 

t  Genth,  Proc.  Araer.  Philos.  Soc,  September,  1873,  and  July,  1874; 
also  Amer.  Jour.  Sci.  (3),  vi.,  401,  and  viii.,  221-223.  Mr.  Dana,  in  a 
notice  of  Dr.  Genth's  conclusions,  in  the  last  citation,  denounces  me 
severely  for  having,  on  a  former  occasion,  cited  from  him  the  words  above 
quoted  by  Genth,  forgetting  that  it  is  Genth  (whom  he  praises),  and  not 
myself,  who  is  thus  attributing  them  to  him,  and  that  Genth's  conclu- 
sions, if  admitted,  form  a  striking  exemplification  of  that  doctrine, 
which  Dana  there  repudiates.  In  the  same  note,  affer  stating  that  I 
have  declared  that  "the  advocates  of  the  doctrine  of  transmutation" 
have  taught  that  "  the  greater  part  of  all  the  so-called  metamorphic  or 
crystalline  rocks  are  the  result  of  an  epigenic  process,"  and  that  "the 
<idvocates  of  this  doctrine  maintain  that  a  mass  of  granite  or  diorite  may 


v.] 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


101 


§  38.  Julien,  who  has  more  recently  studied  these 
rocks,  adopts  with  regard  to  the  chrysolite-beds  the  view 
suggested  by  Clarence  King,  in  1878,  that  they  were 
derived  from  the  disintegration  of  chrysolitic  eruptive 
rocks,  and  were  originally  chrysolite-sandstones.  Cliryso- 
»  lite,  according  to  him,  and  not  corundum,  has  been  the 
point  of  departure  for  the  various  changes  which  have 
given  rise  to  the  crystalline  schists  in  question.  Thus, 
while  some  of  the  chrysolite  beds  remain  unchanged, 
others  have  been  converted  into  strata  of  cellular  cluilce- 
donic  quartz,  of  serpentine,  of  steatite,  of  talcose  actino- 
lite-schist,  of  tremolite-schist,  and  of  a  diorite  or  gabbro 
made  of  albite  and  smaragdite  and  including  grains  of 
red  corundum,  sometimes  with  margarite.  Within  these 
rocks  are  veins  and  fissures  of  various  sizes  and  shapes, 
in  which  are  found  crystallized  corundum,  with  enstatite, 
actinolite,  talc,  and  ripidolite,  among  other  species.  Julien, 
who  assigns  a  similar  origin  to  the  like  crystalline  scliists 
found  elsewhere  throughout  the  Atlantic  belt,  concludes 
that  all  of  these  various  rocks  have  been  derived  from 
chrysolite.  As  regards  the  hypothesis  of  Genth,  he 
writes :  "  The  view  which  has  been  suggested,  founded  on 

be  converted  into  serpentine  or  limestone,  and  that  a  limestone  may  be 
changed  into  granite  or  gneiss,  which  may  in  its  turn  become  serpentine," 
Dana  calls  this  an  extravagant  doctrine,  and  says,  "  I  demonstrated  that 
all  writers  on  pseudomorphism,  with  but  one  or  two  exceptions,  would 
repudiate  it  as  strongly  as  myself."  He  farther  asserts  that  the  state- 
ments here  quoted  "have  been  shown  by  me  to  be  untrue";  and,  with 
regard  to  the  transmutation  of  granite  or  gneiss  into  limestone,  declares, 
in  repeating  his  charges  before  the  Boston  Society  of  Natural  His- 
tory, that  "he  never  knew  any  one  ignorant  enough  or  audacious 
enough  to  have  suggested  it."  (Proc.  Boston  8oc.  Nat.  Hist.,  vol.  xvii., 
p.  170. ) 

Those  who  read  these  pages,  and  will  take  the  trouble  to  consult  the 
authorities  here  cited,  or  given  in  more  detail  in  my  Chemical  and  Geo- 
logical Essays,  pp.  324-326,  may  satisfy  themselves  that  I  have  not  borne 
false  witness  in  this  matter,  but  that  every  one  of  ihe  changes  cited  has 
been  formally  maintained  by  some  one  or  more  of  the  transmutationists. 
It  is  surely  not  more  ditficult  to  transform  granite  into  limestone,  than 
limestone  to  granite,  as  imagined  by  Volger,  or  corundum  to  opal  with 
Genth,  or  chrysolite  to  corundum  with  Julien. 


M'i 


,i:    i 


102 


THE  ORIGIN  OF  CEYSTALLINE  ROCKS. 


l-n 


certain  phenomena  observed  in  the  corundum-veins,  that 
these  secondary  rocks,  and  many  schists,  have  been  de- 
rived from  the  alteration  of  corundum,  finds  not  the  least 
confirmation  from  my  studies,  and  is  indeed  strongly  con- 
tradicted by  facts  observed  in  the  field.  The  corundum 
itself  is,  in  all  cases,  both  in  the  veins  and  in  the  particles 
found  in  the  gabbro,  a  secondary  or  alteration-product. 
All  the  phenomena  of  alteration,  both  in  the  veins  and 
rock-masses,  absolutely  require,  and  can  be  simply  ex- 
Ijlained  by,  die  introduction  of  a  solution  of  soda  and 
alumina  into  tlie  fissures  and  interstices,  during  the 
period  of  alteration  and  metamorphism."  *  This  solution 
he  imagines  to  have  come  from  some  subterranean  source 
in  a  heated  condition.  The  applications  of  the  doctrine 
of  metasomatosis  seem  to  be  limited  only  by  the  imagina- 
tion of  its  disciples. 

§  39.  We  now  come  to  examine  what  v/e  have  called 
the  second  phase  of  the  doctrine  of  metasomatism,  which 
starts,  not  from  «ilicated  and  aluminous  rocks,  but  from 
limestones,  and  from  these  proceeds  to  silicated  rocks. 
The  resources  of  the  chemist  were  severely  taxed,  when 
it  was  required  by  the  metasomatist  to  change  a  sand- 
stone or  an  argillite  into  a  gneiss,  a  hornblende-schist,  or 
a  serpentine  ;  but  with  a  comparatively  soluble  rock,  like 
limestone,  the  change  was  less  difficult  to  conceive.  Ac- 
cordingly, we  find  Von  Buch,  Haidinger,  and  others,  teach- 
ing the  conversioa  of  limestone  into  dolomite,  and  Gustaf 
Rose,  and  Dana,  the  further  change  of  dolomite  into  ser- 
pentine ;  while  Volger,  and  after  him  Bischof,  maintained 
the  transformation  of  limestone  into  gneiss  and  granite. 
The  argument  for  this  change,  as  stated  by  the  latter,  is 
instructive,  as  showing  the  ordinary  mode  of  reasoning 
adopted  by  this  school.  The  occurrence  of  feldspar  in 
the  form  of  calcite,  according  to  him,  "proves  the  possi- 
bility of  carbonate  of  lime  being  replaced  by  a  feluspathic 
substance."      He  elsewhere  argues  that  since  both  quartz 

*  Proc.  Boston  Soc.  Nat.  Hi&t.  (1883)  vol.  xxiii.,  p.  147. 


v.] 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


103 


and  feldspar  may  replace  calcite,  "if  both  changes  take 
place  together,  the  chief  constituents  of  gneiss  would  be 
substituted  for  the  limestone  removed."  "  Volger  also 
describes  instances  of  the  association  of  adularia  and 
pericline  with  calcite,  at  St.  Gothard,  which  sliows  that 
feldspar,  quartz,  and  mica  may  be  substituted  for  the 
carbonale  of  lime  in  calcite.  Consequently,  it  may  be 
inferred  that  granite  or  gneiss  may  be  produced  from 
limestone  in  the  same  manner."  * 

§  40.  Akin  to  this  view  of  Volger  is  that  suggested  by 
Pumpclly  with  regard  to  the  halleflinta  or  bedded  petro- 
silex-porphyry  of  Missouri  (composed  chiefly  of  quartz 
and  orthoclase)  —  that  this  rock,  as  W3ll  as  its  included 
magnetic  and  specular  ii'on  and  manganese  ores,  may  have 
been  derived  by  a  metasomatic  process  from  a  limestone, 
parts  of  which  were  replaced  by  the  oxyds  of  iron  and 
manganese,  "while  the  porphyry  now  surrounding  the 
ores  may  be  due  to  a  previous,  contemporaneous,  or  sub- 
sequent replacement  of  the  lime-carbonate  by  silica  and 
silicates."  Portions  of  this  petrosilex  are,  in  fact,  inti- 
mately mingled  with  calcite,  and  thin  layers  of  crystalline 
limestone  are  also  found  interstratified  with  the  petrosilex, 
wliich,  in  these  associations,  retains  its  normal  composi- 
tion of  a  mixture  of  orthoclase  and  quartz,  f 

The  hypothesis  of  metasomatism  as  applied  to  silicated 
rocks,  endeavors  to  account  for  the  generation  of  different 
and  unlike  masses  in  a  single  crystalline  terrane  or  series, 
and  also  for  certain  phenomena  in  the  transformation  of 
detrital  rocks.  As  applied  to  limestones,  however,  by 
Rose,  Volger,  Bischof,  and  Pumpelly,  it  seeks  to  explain 
the  conversion  of  a  single  widespread  rock  into  granite, 
gneiss,  serpentine,  petrosilex,  and  crystalline  iron  ores. 
These  transformations  once  established,  we  should  have 

*  Bischof;  Chemical  and  Physical  Geology,  1859,  vol.  iii.,  pp.  431, 
432. 

t  Geological  Survey  of  Missouri,  1873;  Iron  Ores,  etc.,  pp.  25-27. 
Also  Hunt,  Azoic  Hocks,  Rep.  E.,  Second  Geological  Survey  of  Penn., 
1   194. 


Ml 


ill; 


•i  m 


104 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


tt* 


w\   I 


M: 


an  intelligible  hypothesis  to  account  for  the  origin  of  the 
principal  crystalline  rocks. 

§  41.  We  have  in  the  preceding  historical  sketch  en- 
deavoried  to  show  that  the  existing  hypotheses  regarding 
the  origin  of  the  stratiform  crystalline  rocks  may  be 
classed  under  six  heads,  which  are  as  follows :  — 

I.  Endoplutonic.  This  supposes  the  rocks  in  ques- 
tion to  have  been  formed  from  the  mass  of  the  primeval 
globe  as  it  congealed  from  igneous  fusion,  and,  as  Nau- 
mann  remarks,  implies  a  solidification  from  without  in- 
wards. The  process  beginning  before  the  precipitation  of 
water  on  the  surface,  this  liquid  took  no  part  in  their  for- 
mation, and  their  stratiform  structure  and  arrangement 
are  to  be  ascribed  to  crystallization,  or  to  the  effect  of 
currents  set  up  in  the  congealing  mass.  (Naumann,  T. 
Macfarlane,  Hdbert,  et  al.^ 

II.  ExoPLUTONic.  This  hypothesis  conceives  the  crys- 
talline stratiform  rocks  to  have  been  built  up  out  of  mat- 
ters ejected  from  beneath  the  sunerficial  crust  of  the 
earth.  Besides  lavas  and  pyroclastic  rocks,  which  are 
the  ordinary  products  of  volcanoes,  the  hypothesis  of  the 
Huttonians  (in  which  the  notion  of  metamorphism  is 
carried  back  indefinitely,  so  that  its  products  are  con- 
founded with  the  primeval  crust)  has  apparently  led  the 
way  to  a  belief  in  the  eruption  not  only  of  re-fused  sedi- 
ments, but  of  hydrated  serpentinic  and  feldspathic  mag- 
mas, and  even,  as  we  have  seen,  of  quartz,  magnetite, 
limestone,  rock-salt,  anhydrite,  and  of  clays  and  sands. 
It  would  not  probably  be  maintained  by  its  advocates  that 
the  eruption  of  all  of  these  rocks  was  attended  with  vol- 
canic phenomena,  properly  so  called.  Such  extruded 
rocks,  though  not  truly  volcanic,  would  h.  wever,  as  com- 
ing up  from  the  underworld,  merit  the  more  comprehen- 
sive designation  of  exoplutonic,  already  proposed. 

III.  Metamorphic  or  plutonic-detrital.  This  hypoth- 
esis conceives  the  crystalline  rocks  to  have  been  formed 
by  consolidation  and   recrystallization  of  sediments  ar- 


y :.  '.     i 


V.1 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


105 


ranged  beneath  the  sea,  and  derived  (1)  from  the  ruins  of 
endoplutonic  rocks  resembling  these,  (Hutton,  and  his 
followers,  Playfair,  Serope,  Boue,  Lyell,  and  Dana  in  1863- 
1879)  ;  (2)  from  exoplutonic  or  volcanic  rocks,  broken  up, 
for  the  most  part,  during  the  process  of  eruption,  which 
was  often  submarine.  With  these  materials  may  also  be 
associated  lava-flows.  (Dana  in  IS'IS,  Kopp,  Reusch, 
Tornebohm,  Marr,  C.  H.  Hitchcock.)  The  heat,  which 
was  believed  to  effect  the  metamorphosis  of  these  detrital 
materials  beneath  the  sea  into  crystalline  rocks,  is  sup- 
posed by  the  Huttonians  to  have  come  from  the  heated 
interior  by  conduction,  but,  according  to  the  volcanic- 
detrital  liypothesis  of  Dana,  through  the  direct  heating  of 
the  waters  of  the  sea  by  contact  with  the  eruptive 
matters. 

IV.  Metasomatic.  Although  the  crystalline  rocks 
believed  to  be  formed  in  each  one  of  the  preceding 
methods  have  been  supposed  to  be  occasionally  the  sub- 
ject of  wide-spread  metasomatosis,  we  may  properly  re- 
strict the  title  of  a  general  metasomatic  hypothesis  to  that 
which  seeks  to  explain  the  derivation  of  the  principal 
crystalline  silicated  rocks  from  limestones,  as  suggested 
by  Rose,  Volger,  Bischof,  and  Pumpelly. 

Y.  Chaotic.  We  have  already  suggested  the  name  of 
the  chaotic  hypothesis  for  that  which  supposes  the  crystal- 
line stratiform  rocks,  as  well  as  the  granites  underlying 
them,  to  have  been  successively  deposited  by  crystalliza- 
tion from  a  general  chaotic  ocean,  by  which  their  elements 
were  originally  held  in  solution.  In  this  doctrine,  which 
was  taught  by  Werner  and  his  immediate  disciples,  the 
conception  of  internal  heat  was  not  recognized,  and  there 
was  no  suggestion  of  an  elevated  temperature  in  the  cha- 
otic ocean. 

VI.  Thermochaotic.  The  history  of  the  attempts  to 
adapt  the  Wernerian  hypothesis  to  tlie  conception  of  a 
cooling  globe  has  already  been  told  in  the  preceding 
pages.     It  was  supposed  that  the  waters  of  the  universal 


106 


THE   ORIGIN   OP   CRYSTALLINE   ROCKS. 


[V. 


chaotic  ocean  were  liiglily  heated,  and  were  thus  enabled 
to  exert  a  powerful  solvent  action  upon  the  previously 
formed  plutonic  rocks  of  the  primitive  crust,  transforming 
them  into  the  present  crystalline  stratiform  rocks ;  a 
hypothesis  of  their  origin  which  may  be  appropriately 
designated  as  therraochaotic.  According  to  tiiis  hypothe- 
sis, as  set  forth  by  Scrope,  and  afterwards  by  De  la  Beche 
and  by  Daubree,  the  first  water  on  the  surface  of  the 
planet  would  be  condensed  under  a  pressure  equal  to  250 
atmosplieres,  corresponding  to  a  temperature  near  that  of 
redness.  We  are  reminded  in  this  of  Dana's  earlier  met- 
amorphic  theory,  in  which  he  also  invoked  the  action  of 
waters  at  a  red  heat.  These,  however,  were  supposed  by 
him  to  be  heated  in  the  depths  of  the  ocean  by  local 
volcanic  eruptions,  and  the  process,  so  far  from  being  a 
universal  one,  belonging  to  a  very  early  time  in  the  history 
of  our  planet,  was  a  partial  one,  repeated  at  different  geo- 
logical periods.  According  to  Daubr^e,  the  original  plu- 
tonic rocks  are  not  known,  and  the  oldest  crystalline 
schists  are  thermochaotic.  Macfarlane,  on  the  contrary, 
while  adopting  this  hypothesis  for  the  later  crystalline  or 
transition  schists,  maintains  the  endoplutonic  origin  of  the 
primitive  gneisses. 

§  42.  Proceeding  now  to  review  briefly  the  claims  of 
the  above  hypotheses,  we  remark  with  regard  to  the  first, 
that  multiplied  observations  in  many  parts  of  the  world 
have  established  the  existence  of  a  regular  succession  in 
the  crystalline  rocks,  which  show  by  the  greater  corruga- 
tion of  the  lower  members,  by  frequent  discordances  in 
stratification,  and  by  the  presence  of  fragments  of  the 
lower  in  the  higljer  strata,  that  the  order  of  generation 
was  from  below  upwards.  With  this,  moreover,  corre- 
sponds the  fact  that  the  lower  rocks  are  the  more  massive 
and  more  highly  crystalline,  while  the  upper  ones  present 
a  gradual  approximation  in  physical  characters  to  the  un- 
crystalline  sedimentary  or  secondary  strata ;  thus  justify- 
ing the  name  of  Transition,  applied  by  Werner  to  these 


▼.J 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


107 


intermediate  rocks.  All  of  these  facts  are  irreconcilable 
with  the  eudoplutonic  hypothesis. 

The  universal  distribution,  and  the  persistency  of  char- 
acters of  these  various  groups  of  crystalline  rocks,  indi- 
cate moreover  that  they  have  been  produced  by  a  world- 
wide action,  extending  with  great  regularity  through  vast 
periods  of  time,  and  are  incompatible  with  anything  which 
we  know  of  the  phenomena  of  vulcanicity.  The  objec- 
tions long  since  made  by  Naumann  to  the  second  or  exo- 
plutonic  hypothesis  are  still  as  valid  as  ever,  and  there  is 
no  evidence  in  the  iithological  characters  of  these  rocks 
of  their  volcanic  origin.  The  argument  derived  from  the 
similarity  between  their  mineralogical  composition  and 
that  of  erupted  rocks  of  paleozoic  and  more  recent  times, 
is  equally  strong  in  favor  of  the  derivation  of  these  latter 
from  the  primitive  strata. 

§  43.  The  metamorphic  hypothesis,  which  would  derive 
the  primitive  strata  from  the  consolidation  and  the  recrys- 
tallization  of  detrital  plutonic  rocks,  whether  eudoplu- 
tonic or  volcanic,  ia  for  many  reasons  inadmissible.  With- 
out at  present  considering  the  later  crystalline  groups, 
which  are  also  of  vast  extent,  the  ancient  granitoid 
gneisses  (originally  called  Laurentian  and  represented  in 
Canada  by  the  Ottawa  and  Grenville  series)  have  an  un- 
known volume,  since  their  base  has  never  been  detected. 
It  is,  however,  certain  that  they  include,  wherever  studied 
in  Europe  or  in  America,  a  vast  thickness,  which,  as  Dana 
cqrrectly  says,  cannot  be  assumed  to  be  less  than  30,000 
feet.  The  detrital  hypothesis  demands  an  agency  which 
shall  create,  transport,  and  lay  down  beneath  the  sea,  over 
vast  areas,  now  continental,  this  enormous  thickness  of 
sediment,  not  of  mingled  sands  and  clays,  like  those  of 
later  deposits  (which  are  the  results  of  a  more  or  less 
complete  sub-aerial  chemical  decomposition  of  primitive 
rocks),  but  in  a  chemically  unchanged  condition,  and 
with  the  feldspar  unaltered.  It,  moreover,  demands  a 
source  for  these  enormous  amounts  of  fresh  detrital  mate- 


108 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


rv. 


rial,  eitlier  in  vanished  pre-Laurentian  continents,  or  in 
vast  volcanic  centres  which  have  left  behind  them  no 
traces  of  their  existence. 

This  hypothesis  further  demands  a  consolidation  and 
recrystallization  of  the  elements  of  these  recomposed 
rocks,  so  perfect  that  the  microscope  fails  to  detect  the 
evidence  of  their  detrital  origin.  The  resemblance  be- 
tween the  primitive  crystalline  rocks  and  what  we  know 
to  be  detrital  rocks,  compressed,  recemented,  and  often 
exhibiting  interstitial  minerals  of  secondary  origin,  is  too 
slight  and  superficial  to  deceive  the  critical  student  in 
lithology,  and  disappears  under  microscopical  examina- 
tion. The  lessons  taught  by  careful  lithological  and 
stratigraphical  study  have  already  led  to  the  abandon- 
ment of  the  metamorphic  hypothesis  by  the  greater  num- 
ber of  geologists ;  the  more  so  since,  as  Bonney  has  well 
remarked,  the  long-quoted  examples  of  metamorphic  sec- 
ondary and  tertiary  rocks  in  Europe  have,  without  excep- 
tion, been  found  to  be  mistaken,  and  to  have  been  based 
either  o'l  false  stratigraphy,  on  cases  of  recomposed 
crystalline  rocks,  or  on  a  local  development  of  crystalline 
minerals  in  the  texture  of  clastic  rocks.*    ' 

§  44.  The  very  ingenious  metasomatic  hypothec's, 
which  would  derive  the  crystalline  stratified  rocks  from 
the  transformation  of  limestones,  is  of  course  a  gratuitous 
one,  based  on  some  observed  cases  of  association  of  sili- 
cates with  calcite,  and  the  possible  replacement  of  the 
one  by  the  others,  and  deserves  mention  only  as  showing 
the  greater  difficulties  of  the  previous  hypothesis,  which 
could  lead  to  the  adoption  of  that  of  general  metasomato- 
sis.  It  is  possible,  however,  that  its  authors  never  imag- 
ined for  it  the  rank  of  a  universal  hypothesis  ;  the  creation 
of  continents  of  limestone,  and  their  subsequent  transfor- 
mation into  the  vast  masses  of  granitoid  gneisses  just 
referred  to,  would  make  as  great  demands  on  our  credulity 
as  the  metamorphic  hypothesis  itself. 

*  Geological  Magazine,  November,  1883,  p.  507. 


m 


v.] 


THE  ORIGIN   OF  CKYSTALLINE   HOCKS. 


109 


As  regards  the  chaotic  hypothesis  of  Werner,  according 
to  which  the  whole  of  the  materials  of  the  crystalline 
rocks  were  originally  dissolved  in  a  primeval  sea,  —  its 
chemical  dilliculties  are  evident  to  the  modern  student. 
That  the  ocean  could  have  ever  held  at  one  time  in  solu- 
tion, under  any  conceivable  conditions,  the  elements  of 
the  whole  vast  series  of  crystalline  rocks,  and  could  have 
deposited  them  successively,  in  that  orderly  manner  which 
we  observe  in  the  earth's  crust,  was  seen  to  be  incredible. 
This  argument,  successfully  urged  by  Playfair  and  his 
followers,  contributed,  with  others,  to  the  discredit  which, 
as  we  have  seen,  soon  fell  upon  the  Wernerian  hypoth- 
esis. 

§  45.  Respecting  what  we  have  called  the  thermo- 
chaotic  hypothesis,  so  ingeniously  set  forth  by  Daubrde, 
—  while  his  conclusions  as  to  the  first  precipitation  of 
water  on  the  globe  at  a  very  high  temperature  are  not  to 
be  questioned,  it  can,  we  think,  be  shown  that  its  direct 
action,  under  these  conditions,  upon  the  primitive  cr'  it 
could  not  have  resulted  in  any  such  succession  of  de])osits 
as  those  which  make  up  the  crystalline  schists ;  these  we 
are  forced  to  assign  to  a  later  period  in  the  history  of  the 
globe,  for  which  the  phase  to  which  Daubrde  has  drawn 
attention  was  but  a  preparation. 

The  mineralogical  characters  and  associations  of  the 
ancient  crystalline  rocks  are,  it  is  maintained,  incompati- 
ble with  the  elevated  temperature  supposed  in  the  hypoth- 
esis of  Daubrde.  The  orderly  interstratification  with  the 
ancient  Laurentian  gneisses  of  beds  of  limestone,  and 
others  of  dolomite,  not  less  than  the  presence  in  the  one 
and  the  other  of  these  of  concretionary  masses  and  beds 
of  serpentine,  after  the  manner  of  flint,  and  the  inclusion 
in  this  of  what  so  many  regard  as  an  organic  form,  the 
Eozoon  Canadense ;  the  presence,  alike  in  the  limestones, 
gneisses,  and  associated  quartzites,  of  carbon  in  the  form 
of  graphite  ;  and,  finally,  the  occurrence  of  sulphids,  tes- 
tifying to  a  process  of  reduction  of  sulphates  (which,  not 


110 


THE  OIUOIN   OF  CRVSTALLINK  ROCKS. 


[V. 


V'l  I 


less  than  the  graphite,  suggests  organic  matter),  all  indi- 
cate chemical  processes  such  as  arc  now  going  on  at  the 
earth's  surface,  and  have  been  in  operation  since  the  be- 
ginning of  paleozoic  time  ;  but  which  are  inconsistent 
with  any  conaiderable  elevation  of  temperature  above 
that  now  prevailing  on  the  earth.  They  are,  in  short, 
evidences  that  tiio  processes  of  vegetable  and  animal  life 
were  going  on  simultaneously  with  the  deposition  of 
the  rocks  of  the  Laurentian  period.  More  than  this,  the 
presence  of  rounded  masses  of  older  gneisses  in  the 
younger  crystalline  schists,  not  less  than  the  composition 
of  these  schists  (as  we  shall  hope  to  show  in  the  sequel), 
are  evidences  that  during  the  period  in  question  a  sub-ae- 
rial decay  of  the  older  crystalline  rocks  was  already  going 
on,  giving  rise  to  boulders  of  decomposition,  to  clays,  and 
all  the  chemical  reactions  which  that  process  implies,  and 
which  I  have  elsewhere  set  forth  at  lenoth.* 

§  46.  If  we  have  correctly  defined  the  conditions  requi- 
site for  the  production  of  the  crystalline  stratified  rocks, 
they  must  have  been  separated  from  water  bj'^  a  process  of 
crystallization  or  precipitation,  at  a  temperatire  and  a 
pressure  not  widely  different  from  those  now  prevailing 
at  the  earth's  sui-face.  This  process,  in  the  earlier  periods, 
must  have  been  widely  extended,  and,  so  far  as  known 
continental  areas  were  concerned,  probably  universal.  A 
slowly  progressive  change  meanwhile  went  on  in  the 
chemical  conditions,  indicated  by  a  gradual  modification 
in  the  composition  of  the  rocks,  and  the  areas  of  deposi- 
tion, though  still  very  great,  became  limited,  leaving  large 
surfaces,  both  of  subsequently  erupted  rocks  and  of  the 
precipitated  stratified  rocks,  exposed  to  a  process  of  sub- 
aerial  decay,  the  soluble  and  insoluble  products  alike  of 
which  intervened  in  the  rock-forming  processes  of  this 
later  or  transition  period.  The  conditions  of  the  problem 
before  lis  require  moreover  a  source,  neither  detrital  nor 

*  The  Decay  of  Rocks  Geologically  Consirlcred,  1883.  Amer.  Jour, 
ScL,  vol.  xxvl.,  pp.  190-213,  &ho,  post,  Essay  VIII. 


v.] 


THE  OHIO  IN   OP  CUYSTALLINE   UOCK3. 


Ill 


volcanic,  for  the  immense  mass  of  wholly  crystalline  mate- 
rial, chiefly  quartz  anil  t'eldspars,  constituting  the  vast  and 
as  yet  unfuthomod  primitive  granitic  and  gneissic  series ; 
which  only  at  a  later  time  furnished  its  contingent  of  de- 
cayed and  detrital  matter  to  the  crystalline  transition 
rocks. 

lint  there  is  still  another  condition  imposed  by  the 
problem  before  us  —  that  of  a  satisfactory  explunation  of 
the  highly  inclined  and  often  nearly  vertical  attitude 
of  the  crystalline  stratified  rocks,  wliich  is  most  remarka- 
ble in  those  of  the  earliest  periods.  The  ordinarily 
received  exi)hinaU()n  of  this,  as  due  to  the  contraction  of 
a  cooling  globe,  has  seemed  so  inadequate  to  account  for 
the  great  contortion,  crushing,  and  folding  of  these  older 
rocks,  that  some  geologists,  as  Naumann  tells  us,  have  been 
led  to  regard  the  present  as  their  original  attitude,  result- 
ing from  movements  of  the  solidifying  crust ;  in  which 
connection  he  quotes  with  approval  the  language  of  Kit- 
tel,  that  "so  long  as  a  hypothesis  is  unable  thoroughly  to 
explain  the  almost  vertical  position  of  the  primitive  strata, 
it  cannot  be  regarded  as  even  approximately  near  the 
truth." 

It  will,  we  think,  be  apparent,  in  the  light  of  the  pre- 
ceding review  of  existing  hypotheses,  that  no  exi)lanation 
of  the  origin  of  the  crystalline  rocks  which  fails  to  meet 
all  of  the  conditions  just  defined  can  hope  for  the  approval 
of  those  who,  after  a  careful  survey  of  the  whole  field, 
seek  for  a  new  and  more  satisfactory  hypothesis.  It  re- 
mains to  be  seen  whether,  with  the  help  of  modern  physi- 
cal and  chemical  science,  and  our  present  knowledge  of 
geological  facts,  it  is  possible  to  devise  such  a  one.  After 
many  years  of  reflection  and  study,  the  present  writer 
ventures  to  propose  a  new  hypothesis,  believing  that, 
while  avoiding  all  the  difficulties  of  those  hitherto  put 
forward,  it  will  furnish  an  intelligible  solution  of  a  great 
number  of  hitherto  unsolved  problems  in  the  physiology 
of  the  globe. 


vf>  . 


mi 


ill 


'if S  'IS 

■11 


112 


THE   ORIGIN   OF  CRYSTALLINE  KOCKS. 


tv. 


M';!,-! 


I  !'! 


II.  —  THE  DEVELOPlSrENT   OP  A  NEW   HYPOTHESIS. 

§  47.  The  history  of  the  beginning  and  the  growth  of 
the  new  hypothesis  here  proposed  to  explain  the  origin  of 
crystalline  rocks  is  necessarily  to  a  great  extent  personal, 
since  it  covers  the  work  of  many  years  of  the  author's 
life.  The  lines  of  investigation  which  have  led  to  this 
hypothesis  may  be  described  as,  first,  that  of  the  order  and 
succession  of  the  crystalline  stratified  rocks  of  the  earth's 
crust;  secondly,  their  mineralogy  and  lithology;  thirdly, 
their  history,  considered  in  the  light  of  phj'sics  and  chem- 
istry, involving  an  inquiry  into  all  the  chemical  relations 
of  existing  rocks,  waters,  and  gases,  including  the  trans- 
formations and  decay  of  rocks,  and  the  artificial  production 
of  mineral  species ;  and  fourth  and  lastly,  the  probable 
condition  of  our  planet  before  the  creation  of  the  present 
order.  The  adequate  discussion  of  all  these  themes,  which 
would  include  a  complete  system  of  mineral  physiology, 
is  impossible  within  the  limits  of  the  present  essay,  but  a 
brief  outline  of  some  of  the  chief  points  necessary  to  the 
understanding  of  the  hypothesis  will  here  be  attempted. 

§  48.  As  regards  the  order  and  succession  of  the  crys- 
talline rocks,  the  author's  studies  of  them,  begun  in  New 
England  forty  years  since,  and  continued  in  Canada  from 
1847  onwards,  were  for  many  years  perplexed  with  the 
difficulties  of  the  Huttonian  tradition  (then  and  for  many 
years  generally  accepted  in  America),  that  the  mineral 
character  of  these  rocks  was  in  no  obvious  way  related  to 
their  age  and  geological  sequence,  but  that  the  strata  of 
paleozoic  and  even  of  cenozoic  times  might  take  on  the 
forms  of  the  so-called  azoic  rocks.  It  was  questioned  by 
the  partisans  of  the  Huttonian  school  whether  to  the 
south  and  east  of  the  azoic  rocks  of  the  Laurentides  and 
the  Adirondacks,  in  North  America,  there  were  any  crys- 
talline strata  which  were  not  of  paleozoic  or  of  mesozoic 
age,  although  many  of  these  are  undistinguishable  from 
the  rocks  of  the  Laurentides. 


%1 


THE  ORIGIN   OF  CRYSTALLINE  ROCIiS. 


113 


As  I  have  elsewhere  said,  tlie  metamorphic  and  the 
metasomatic,  not  less  than  the  exoplutonic  hypothesis  of 
the  origin  of  the  crystalline  rocks,  by  failing  to  recognize 
the  existence  and  the  necessity  of  an  orderly  lithological 
development  in  time,  have  powerfully  contributed  to  dis- 
courage intelligent  geognostical  study,  and  have  directed 
attention  rather  to  details  of  lithology  and  of  mineralogy, 
often  of  secondary  importance.*  That  a  great  law  pre- 
sided over  the  development  of  the  crystalline  rocks,  was 
from  the  first  my  conviction;  but  until  the  confusion 
which  a  belief  in  the  miracles  of  metamorphism,  metaso- 
matism, and  vulcanism  had  introduced  into  geology  was 
dispelled,  the  discovery  of  such  a  law  was  impossible. 

§  49.  Convinced  of  the  essential  trutli  of  the  princi- 
ples laid  down  by  Werner,  and  embodied  in  his  dis- 
tinctions of  Primitive,  Transition,  and  Secondary  rocks, 
I  sought,  during  many  years,  to  define  and  classify  the 
rocks  of  the  first  two  of  these  classes,  and  by  extended 
studies  in  Europe,  as  well  as  in  North  America,  succeeded 
in  establishing  an  order,  a  succession,  and  a  nomencla- 
ture, which  are  now  beginning  to  find  recognition  on  both 
continents,  f 

While  the  succession  of  the  various  groups  of  crystal- 
line rocks  was  thus  being  established,  not  without  the 
efficient  aid  and  co-operatiou  of  other  workers  in  late 
years,  mineralogical  and  chemical  studies  were  teaching 
us  much  of  the  true  nature  of  the  differences  and  resem- 


1 


*  Amer.  Jour.  Science,  1880,  xix.,  298. 

t  I  have  elsewhere  given  tlie  history  of  the  progress  of  inquiry  in  tliis 
direction  in  Report  E  of  tlie  Second  Geological  Survey  of  Pennsylvania 
(Azoic  Rocks)  1878;  in  brief,  in  an  essay  on  Pre-Cambrian  Rocks,  etc.,  in 
the  Amer.  Jour.  Science,  1880  (xiv.,  2G8);  and  later  in  a  study  of  the 
Pre-Cambrian  Rocks  of  the  Alps,  in  the  Trans.  Roy.  Soc.  Canada, 
pout,  Essays  X  and  XI.  See  also  in  this  connection  the  late  address  of 
Dr.  Hicks,  President  of  the  British  Geologists'  Association,  in  its  Proceed- 
ings, vol.  viil.,  1883,  On  the  Succession  of  the  Archsean  Rocks,  etc.;  and 
the  still  more  recent  paper  of  Prof.  Bonney,  President  of  the  Geological 
Society  of  London,  on  The  Building  of  the  Alps,  in  Nature  iov  May  18 
and  25, 1884;  also  the  Geological  Magazine  for  June,  1884,  p.  '280. 


i 


114 


^n^  OBIGIN  OF  CRYSTALLINE  BOCKS. 


IT. 


ill  a.»— 

.  «.ll  as  of  the  natural  relations 
Uancesot  these  grours.;.s  wen  as        ^.^.^^^^^  ^^^^ 

and  modes  of  «""!^*™4  -^.^  the  composition  of  the 
mineral  speeies  ^^!"»|^^f !  ^^.^  tig.tions  of  physiosts  and 
crystalline  rocks.     !'«  '"„  fo^m  and  consistence  to 

Jronomers  had,  ^^T^^^^  origin  of  our  planet  and 
the  ancient  theory  o  the  >gne  b     ^._^^^  ^^  j^^^^^j^g^. 

the  eonem'rent  workmg      J  ■       the  way  tor  ^  new 

tion  above  indicated  wa»  «" » l^^Pii^^^'^eks  -  a  hypothe- 

'■>Tf*whioif  l'^^^^^^^^^^^  "'^^'■■'"""" 

*T^"":s  in  January  «58  - 
ac;nt«rysince,thatlventar  dtopu  ^^^^  ^^^^^^ 

^  to  the  «l-"f' y  °'  *,^°t  vii  which  geognosy  makes 
Considering  only  that  «  "«  j  ^^at  at  a  very  early 

„,  accinainted    It  was  —    .,^  ^„,„,„t,  were  um  ed 
period  tlie  whole  of  '»    ""^J'^tvich  included  the  metalUo 
i„  a  fused  mass  o£  s'>"'»,*.^,"' J"  ,  ;„  the  ocean's  waters; 
bases  of  the  salts  ^^^f'ffXtUme  was  charged  with 
„hile  the  dense  ''f '^P^'^^X  ne,  combined  with  oxy- 
all  the  carbon,  f  P'^«' ^^y  *,vhich  were  present  watery 

gen  or  with  ^^y^^o^'^^'^ZhMe  excess  of  oxygen.    The 
vapor,  nitrogen,  and  a  P  *^»  "      j,.„„  tfe  atmosphere, 

Jt  precipitated  and  ^^^  ^l^^^^  ,,„,t,  would,  it  was 
falling  on  the  hot  ^-^^^J\    a,,  protoxyd  bases  giv- 
«aid,  soon  become  "«"f  ^  J^V,^ates  of  the  primeval  sea 
i„g  rise  to  the  chlonds  "d  sulp  ^^i„ed  silica,  at 

wife  the  probable  sep—  of  tj^  ^^  .,„      „g. 

■       that  high  t«"r       ;  'a  are  of  the  primitive  atmosphere, 
gestion  as  to  the  ae.d  "^'"^  °\,u,h  were  obvious  deduo- 

Snd  its  first  «l'«™''=f  Jf 'X;  y,  W.  ^»    I    ^''^"™'^ 
tions    from  the  ^g"''"™  *  Q^nstedt. « 

^  ^  #EpocbeuderNatur,p.20. 


v.] 


THE   ORIGIN    OF   CRYSTALLINE   ROCKS. 


115 


William  Hopkins.  The  subsequent  sub-aerial  decay  of 
exposed  portions  of  the  earth's  primitive  crust  in  a  moist 
atmosphere,  now  purged  of  the  acid  compounds  of  chlo- 
rine and  sulphur,  but  still  holding  carbonic  acid,  was  tlien 
set  forth  as  resulting  in  the  transformation  of  feldspathic 
silicates  into  clays,  and  the  transference  to  the  sea  of  the 
lime,  magnesia,  and  alkalies  of  the  decayed  roc^'.  in  the 
form  of  carbonates,  the  latter  of  wdiich,  reacting  on  cal- 
cium-chlorid,  would  3deld  carbonate  of  lime  and  chlorids 
of  sodium  and  magnesium.  It  was  then  said  that  by  this 
hypothesis  "  we  obtain  a  notion  of  the  processes  by  which, 
from  a  primitive  fused  mass,  may  be  generated  the  various 
silicious,  argillaceous,  and  calcareous  rocks  which  make 
up  the  greater  part  of  the  earth's  crust."  Of  this  it  was 
declared,  "  the  earth's  solid  crust  of  anhydrous  and  primi- 
tive igneous  rock  is  everywhere  deeply  concealed  beneath 
its  own  ruins,  which  form  a  great  mass  of  sedimentary 
strata,  permeated  by  water,"  and  subjected  to  heat  from 
below,  changing  them  to  crystalline  metamorpliic  rocks, 
and  at  length  reducing  them  to  a  state  of  igneo-aqueous 
fusion,  th^'ough  which  they  yield  eruptive  rocks.  Of  this 
primitive  rust  it  was  farther  asserted  that  it  "  probably 
approached  dolerite  in  composition." 

The  principal  points  in  this  hypothesis,  as  presented  in 
1858,  were  thus  the  solid  condition  of  the  earth's  interior, 
and  the  derivation  of  the  whole  of  the  rocks  of  the 
known  crust,  by  chemical  transformations,  from  the  origi- 
nal superficial  and  last-congealed  layer  of  the  cooling 
globe,  which  was  considered  to  have  been  a  basic  rock, 
not  unlike  dolerite.  All  of  these  positions  are  fundamen- 
tal to  the  present  hypothesis. 

§  52.  These  views  Avere  again  repeated  in  a  paper  read 
before  the  G  ological  Society  of  London  in  June,  1859, 
with  some  farther  developments  as  to  the  origin  of  the 
various  crystalline  rocks  derived  from  the  primeval  crust. 
This,  it  was  claimed,  was  necessarily  quartzless,  and  far 
removed  in  composition  from  the  supposed  granitic  sub- 


M 


^  If) 


,HE  OKlom   O^  CMST^LUSr,  BOCICS. 


IIQ  THE  OBIGI-N    ui. 

All  attempt  was,  liow- 
stratum,  or  tl>^P"'";«;\S»^  fte  quart;,  derived  from  the 
ever,  made  to  show  that  ""^  "' '1  ,      primitive  igneous 
slpilosed  first  d^^^^P^t   "  td  mente  resulting  from 
■oei.  by  acid  «»*<=«' "J"^  *d  sub-aevial   decay,  coarse' 
subsequent  di^'»*fS'"*l\Xs  permeable,  would  result, 
and  finer  sediments,  moie  « '''^^  |      „f  infiltrating  waters 
Uich  by  the  natural  o^-^-^lJ^vs,  divide  themselves 
„iglrt,  in  »c«»dance  vv  th  know  ^^^^^.^^^  ^^         ,^ 

into  two  great  c  asse  •     «-  «  ,  ,^„,,  „£  potash,  and  by 


g,eat  classes,  "tire  <»";  ^^f 'otash,  and  by 

eess  of  slica,  ^^X  t^^^P^^t:    •      -^^°'^  ""'  T 
counts  of  Inne,  magn  ^^,^;j^  ;„  the  other 


m  11  amounts  of  -•  f  8'  ^  e^  wbUe  »  the  other 
,,„ted  by  the  gramtes  a.^  t^arf'jt  .  _^_^^^  ^^^_^^ ..  ^^^^^  ^^^ 
silica  and  potash  are  less  abun        ,  ^_^^^        ; 

magnesia  prevail,  gmng  "f  *"„]  ^ii.piace' aent  of  sueh 
feldspars.  The  ™^*-»"^"~^p,ain  the  origin  of  the 
sediments  -^^Y  th-  «naUe^:  ocks  without  calling  to  our 

geneo«sundifEerent,ated    rus,w   ho  ^^^^^.^^^  ^^  ^^^  ^^„ 

llutonie  matters  ,  "^  *';yf;,ystalline  rocks;  gnersses, 
great  types  of  acrd.c  and  basic  cy        ^^^^^  ^^^  ^ 

Iranites,  and  trachytes  on  the  ^^^^^,,    ,j^g,,aed 

focks,  greenstones,  and  ^^sato  °n   ^^^  ,,,,;,  to  the 

as  an  attempt  to  ''dapt  *hoJ:lu  ^  ^^^,  ,t 

•    growing  demands  of  *""      „t  in  time,  and  a  po^r- 
lad  hitherto  lacked  a  ^^rtrng  P"  ^_^^  ^^^.^      fe, 

ble  explanation  of  the  W"  t^f  ^  ^j^^  j^i^tory  of  geology, 
tuis  scheme  d-»d-  f  J^ts  author,  it  must  share  the 
although,  m  the  3uag  j^^^_ 

.      for  the  references  to  this  early  «^a»t  the  f   ^  ^^^^^^^^^  ^^ 

Geological  Essays,  pp.  l-l"^- 


.v.i 


THE  ORIGIN   OF  CRYSTALLINE  ROCKS. 


117 


fate  of  all  other  forms  of  the  metamorphic  hypothesis. 
In  recognizinj^  the  adequacy  of  a  primitive  undifferen- 
tiated layer  of  igneous  rock  as  the  source  of  the  materials 
of  the  future  order  it,  however,  effected  a  great  stej)  to- 
wartUi  a  more  satisfactory  hypothesis. 

§  54.  The  nature  and  history  of  this  primitive  layer 
were  farther  discussed  by  the  author  in  a  lecture  on  "  The 
Chemistry  of  the  Primeval  '""-arth,"  given  at  the  Royal 
Institution  in  London,  in  June,  1867.*  Therein  it  was 
said :  "  It  is  with  the  superficial  portions  of  the  fused 
mineral  mass  of  the  globe  that  we  have  now  to  do,  since 
there  is  no  good  reason  for  supposing  that  the  deeply 
seated  portions  have  intervened  in  any  direct  manner  in 
the  production  of  the  rocks  which  form  the  superiicial 
crust.  This,  at  the  time  of  its  first  solidification,  pre- 
sented probably  an  irregular  diversified  surface,  from  the 
result  of  contraction  of  the  congealing  mass,  v/hich  at 
last  formed  a  liquid  bath  of  no  great  depth,  surrounding 
the  solid  nucleus."  It  was  further  insisted  that  this  mate- 
rial would  contain  all  of  the  bases  in  the  form  of  silicates, 
and  must  have  much  resembled  in  composition  certain 
furnace-slags  or  volcanic  products.  Of  this  primary  lava- 
like rock,  it  was  said,  that  it  is  now  everywhere  concealed, 
and  is  not  to  be  confounded  with  the  granitic  substratum. 
That  granite  was  a  secondary  rock,  formed  through  the 
intervention  of  water,  waa  then  argued  from  the  presence 
therein,  as  a  constituent  element,  of  quartz,  "  which,  so 
far  as  we  know,  can  only  be  generated  by  aqueous  agen- 
cies, and  at  comparatively  low  temperatures."  The  meta- 
morphic hypothesis  of  the  origin  of  granite  was  then 
maintained. 

In  1 869,  in  an  essay  on  "  The  Probable  Seat  of  Volcanic 
Action,"  t  a  further  inquiry  was  made  into  the  probable 

*  Proceedings  of  the  Royal  Institution,  and  also  Chemical  and  Geo- 
logical Essays,  pp.  .35-45. 

t  Geological  Magazine  for  June,  1809,  and  Amer.  Jour.  Science,  for 
July,  1870  (vol.  i.,  p.  21).  See  also  Chemical  and  Geological  Essays, 
pp.  59-67. 


>4':\ 


I--- 


I 


rnii 


I'  111;-!  i!l|i| 


i  II 


118 


THE  ORIGIN  or  CRYSTALLINE  ROCKS. 


nr. 


nature  "nd  condition  of  what  had  been  spoken  of  in  1858 
as  "the  ruins  of  the  crust  of  anhydrods  and  primitive 
igneous  rock."  This,  it  was  now  said,  "  must  by  'contrac- 
tion in  cooling  have  become  porous  and  permeable,  for  a 
considerable  depth,  to  the  waters  afterwards  precipitated 
upon  its  surface.  In  this  way  it  was  prepared  alike  for 
mechanical  disintegration  and  for  the  chemical  action  of 
the  acids  .  .  .  present  in  tlie  air  and  the  waters  of  the 
time.  .  .  .  The  e?.rth,  air,  and  water,  thus  made  to  react 
upon  each  other,  constitute  the  first  matters,  from  which, 
by  mechanical  and  chemical  transformations,  the  whole 
mineral  world  known  to  us  has  been  produced."  It  was 
farther  argued,  from  many  geological  phenomena,  that  we 
have  evidence  of  the  existence  between  the  solid  nucleus 
and  the  stratified  rocks  of  "an  interposed  layer  of  par- 
tially fluid  matter,  which  is  net,  however,  a  still  unsolidi- 
fied  portion  of  the  once  liquid  globe,  but  consists  of  the 
outer  part  of  the  congealed  primitive  mass,  disintegrated 
and  modified  by  chemical  and  mechanical  agencies,  im- 
pregnated with  water,  and  in  a  state  of  igneo-aqueous 
fusion."  * 

*  Prestwich,  in  a  memoir  presented  to  the  Royal  Society  of  London, 
April  16,  1885,  of  wliicli  an  abstract  appears  in  Nature  for  April  23, 
after  considering  (1)  the  flexibility  of  the  earth's  crust  as  shown  In  fold- 
ings and  corrugations,  and  in  secular  depressions  and  e;3vations  of  con- 
tinental areas;  (2)  the  increase  of  temperature  in  the  depths,  and  (3) 
the  volcanic  phenomena  of  the  present  day,  and  the  outpouring  of  vast 
sheets  of  trappean  rocks  during  late  geological  periods,  and  after  discuss- 
ing the  bearing  of  these  upon  various  of^  ,r  geological  hypotheses, 
enounces  a  similar  view  to  that  set  forth  above,  and  farther,  in  §  127. 
He  concludes  that  all  these  phenomena  "are  most  compatible  with  the 
movement  of  a  thin  crust  on  a  slowly  yielding  viscid  body  or  layer,  also 
of  no  great  thickness,  and  wrapping  around  a  solid  nucleus.  The  viscid 
magma  is  thus  compressed  between  the  two  solids,  and  while  yielding  in 
places  to  compression,  it,  as  a  consequence  of  its  narrow  limits,  expands 
in  like  proportion  In  conterminous  areas."  It  would  be  difficult  to  ex- 
vess  more  concisely  or  more  correctly  the  view  of  the  earth's  interior 
already  set  forth  by  the  author  in  1860,  in  his  discussion  of  "  The  Prob- 
able Seat  of  Volcanic  Action."  The  intervention  of  water  in  this 
primary  plutonic  magma,  which  Prestwich  appears  to  reject,  is,  in  the 
writer's  opinion,  inevitable.        ' 


v.] 


THE  CKENITIC   HYPOTHESIS. 


119 


§  55.  Although  in  1858  I  had,  as  ah-eady  shown, 
sought  to  give  a  more  rational  basis  to  the  metamorpliic 
hypothesis  of  the  origin  of  crystalline  rocks,  the  tradi- 
tions of  which,  as  expounded  by  Lyell,  weighed  so  heavily 
on  tlie  geologists  of  the  time,  other  considerations  soon 
afterwards  led  me  to  seek  in  another  direction  for  the 
solution  of  the  problem.  The  examination  of  the  mineral 
silicates  deposited  during  the  evaporation  of  many  natural 
waters,  that  of  the  Ottawa  river  among  others,  and  the 
study  which  I  had  made  of  the  hydrous  magnesian  silicate 
found  in  the  tertiary  strata  of  the  Paris  basiii,  induced 
me,  as  early  as  1860,  to  inquire  "to  wiiat  extent  rocks 
composed  of  calcareous  and  magnesian  silicates  may  be 
directly  formed  in  the  moist  way  " ;  and  again,  in  the  same 
year,  to  declare  with  regard  to  the  latter,  "  it  is  evident 
that  such  silicates  could  be  formed  in  basins  at  the  earth's 
surface,  by  reactions  between  magnesian  solutions  and 
dissolved  silica  "  ;  a  consideration  which  was  then  applic.d 
to  the  generation  of  serpentine  and  of  talc.  Again  in 
1863  and  1864,  I  ventured  to  conclude  that  "  steatite,  ser- 
pentine, pyroxene,  hornblende,  and,  in  many  cases,  garnet, 
epidote,  and  other  silicated  minerals,  are  formed  by  a 
crystallization  or  molecular  re-arrangement  of  silicates 
generated  by  chemical  processes  in  waters  at  tlie  earth's 
surface."  * 

§  56.  While  natural  waters  hold  in  abundance  both 
lime  and  magnesia,  alumina  is,  under  ordinary  conditions, 
insoluble  in  them,  and,  moreover,  is  not  found  vuicom- 
bined  with  silica.  The  problem  of  the  genesis  of  the  alu- 
minous double  silicates,  so  abundant  in  the  rocks,  was 
therefore  a  more  difficult  one  than  that  of  tlie  simple  prot- 
oxyd-silicates,  with  which  they  are  often  intimately  asso- 
ciated. Many  facts  In  the  history  of  r.eolitic  minerals, 
however,  soon  led  me  to  recognize  in  the  conditions  under 
which  these  aluminous  double  silicates  are  formed,  a  clew 


*  For  citations  and  references  see  Chemical  and  Geological  Essays, 
pp.  206,  297,  and  300. 


120 


THE  ORIGIN  OP  CHYSTALLINE  ROCKS. 


m 


f '.;! 


«|ll|!i 


to  the  8L,lution  of  the  problem.  Thus  it  was  that,  in  an 
essay  read  before  tlie  Geological  Society  of  Dublin,  in 
April,  18G3,*  I  called  attention  to  the  observations  of 
Daubrd'e  on  the  production,  during  the  historic  period,  of 
the  zeolites,  chabazite  and  harmotome  (phillipsite),  by 
the  action  of  thermal  waters  at  a  temperature  not  above 
70°  C,  on  the  masonry  of  the  ancient  Roman  baths  at 
Plombieres.  The  mode  of  the  occurrence  of  these  miner- 
als showed  that  the  aluminous  silicate  of  the  burned 
bricks  had  been  changed  into  a  temporarily  soluble  com- 
pound, which  had  crystallized  in  cavities  as  zeolites,  — 
species  which  differ  in  composition  from  feldspars  only  by 
the  presence  of  combined  water.  I  also  called  attention, 
in  this  connection,  to  the  experiments  of  Daubrde,  who, 
by  operating  at  higher  temperatures  in  sealed  tubes,  had 
succeeded  in  producing  crj-stallized  quartz,  pyroxene,  and, 
apparently,  feldspathic  and  micaceous  minerals. 

§  57.  The  aqueous  origin  of  feldspars,  and  their  inti- 
mate relations  to  zeolites  and  other  hydrous  minerals, 
were  farther  noticed  by  the  author,  in  the  "Geology  of 
Canada,"  in  1863,  in  which  he  cited  the  observations 
made  by  J.  D.  Whitney  on  the  frequent  occurrence  of 
orthoclase  in  the  copper-bearing  veins  in  the  melaphyres 
of  Lake  Superior.  The  crystals  of  this  mineral,  which 
had  been  mistaken  for  stilbite,  are  there  found  under  con- 
ditions which  show  their  formation  contemporaneously 
with  the  zeolites,  analcime  and  natrolite ;  while  elsewhere 
in  the  same  region,  the  associates  of  the  orthoclase  are 
epidote,  calcite,  native  copper,  and  quartz,  upon  which,  as 
well  as  upon  saponite,  the  crystals  of  the  feldspar  were 
found  implanted.f  Whitney  recalled  in  this  connection 
the  occurrence  of  a  variety  of  orthoclase,  the  weissigite  of 
Jenzsch,  with  chalcedony,  in  cavities  of  an  amygdaloid. 

[Mr.  George  F.  Kunz  has  since  discovered  orthoclase  in 

*  The  Chemistry  of  Metaraorphic  Rocks;  DubUn  Quarterly  Journal 
for  July,  1863;  reprinted  in  Chemical  and  Geological  Essays,  pp.  18-34. 
t  Wliitney,  Amer.  Jour.  Science,  1869,  vol.  zxviii.,  p.  16. 


;  'ii ; 


v.] 


THE  CRENITIC   HYPOTHESIS. 


121 


the  mesozoic  diabase  of  New  Jersey.  Tlie  specimei.  ately 
shown  to  the  New  York  Academy  of  Sciences  are  de- 
scribed by  him  as  "  compact  veins  and  crystals  of  tlesh-red 
primitive  orthoclase,  formed  directly  on  the  diabase,"  and 
sometimes  in  a  granular  form  making  up  the  chief  part  of 
veins  traversing  this  rock.  "The  veins  are  usually  per- 
pendicular, running  east  and  wost,  varying  in  thickness 
from  half  an  inch  to  four  inches,  and  were  evidently 
formed  by  deposition  directly  on  the  walls  of  diabase.  On 
each  side  of  the  orthoclase,  milky  quartz,  either  massive 
or  at  times  in  imperfect  crystals,  is  implanted.  On  the 
orthoclase  and  quartz  alike,  calcite,  massive  and  crystal- 
lized, and  also  apophyllite,  datolite,  pectolite,  and  the 
zeolitic  minerals  are  often  deposited.  Scattered  through 
the  orthoclase  and  quartz  are  found  pyrite,  chalcopyrite, 
and  occasionally  galenite — all  of  these  in  perfect  isolated 
crystals.  The  veins  are  frequently  made  up  entirely  of 
quartz,  both  massive  and  crystalline,  neither  calcite  nor 
any  zeolitic  minerals  having  been  deposited  upon  them. 
The  zeolitic  minerals  are  usually  deposited  directly  upon 
the  diabase."  The  careful  observations  by  Mr.  Kunz  of 
these  veins,  which  according  to  him  are  frequently  found 
in  the  excavations  in  Bergen  Hill,  at  Weehawken,  throw 
much  light  on  the  relations  of  the  zeolites  to  feldspathic 
and  granitic  aggregates.] 

[Garnet  is  found  in  similar  associations,  Mr.  Charles 
Robb,  having,  in  1882,*  noticed  its  occurrence  in  a  vein  in 
the  diabase  of  St.  Ignace  Island,  Lake  Superior,  implanted 
in  prehnite,  with  laumontite,  quartz,  calcite,  barite,  mag- 
netite, native  silver,  copper-glance,  and  a  chloritic  matter. 
A  specimen  of  this  received  from  him  shows  dodecahedral 
garnets,  reddish  brown  in  color, f  two  or  three  millimetres 
in  diameter,  and  small  octohedrons  of  magnetite  on  prehn- 
ite with  laumontite.] 

§  58.   The  facts  noted  by  Whitnej'^  were  insisted  upoii, 

*  Communication  to  the  New  York  Academy  of  Sciences,  May  25, 1885. 
t  Cauadiau  Naturalist,  x.,  176. 


122 


\. 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


[V. 


i 


v^ 


in  connection  with  my  own  observations,  to  prove  the 
aqueous  origin  of  the  feldspar  found  in  veins  among  crys- 
talline schists  in  the  province  of  Quebec,  wiiero  "a  llesh- 
red  orthoclase  occuis  so  intermingled  with  white  quartz 
and  chlorite  as  to  show  the  contemporaneous  formation  of 
the  three  species.  The  orthoclase  generally  predominates, 
often  reposing  upon  or  surrounded  by  chlorite,  and  at 
other  times  imbedded  in  quartz,  which  covers  the  latter. 
Drusy  cavities  are  also  lined  with  small  crystals  of  the 
feldspar,  and  have  been  subsequently  filled  up  by  a  cleav- 
able  bitter-spar,"  often  with  crystaUized  hematite,  rutile, 
and  copper-sulphids.  It  was  shown  that  among  these 
veins,  then  described  as  of  aqueous  origin,  there  was  to  be 
seen  a  transition,  from  those  "  containing  only  quartz  and 
bitter-spar,  with  a  little  chlorite  or  talc,  through  others  in 
which  orthoclase  appears,  and  gradually  predominates, 
until  we  arrive  at  veins  made  up  of  quartz  and  feldspar, 
someiimes  including  mica,  and  having  the  character  of  a 
coarse-grained  granite  ;  the  occasional  presence  of  copper- 
sulphids  and  hematite  characterizing  all  of  them  alike." 
There  was  also  described  the  occurrence,  in  the  same 
region,  of  a  dark-colored  argillaceous  and  schistose  rock, 
having  in  parts  the  aspect  of  a  chloritic  greenstone,  which 
is  rendered  amygdaloidal  by  the  presence  of  numerous 
spherical  or  ovoidal  masses  of  quartz,  or  more  commonly 
of  reddish  orthoclase,  often  with  a  nucleus  of  quartz.  In 
schistose  varieties  of  this  rock  the  feldspar  extends  from 
these  centres  in  such  a  manner  as  to  give  a  gneissoid 
aspect  to  the  mass.  All  of  these  facts  were  regarded  as 
showing  the  aqueous  origin  of  orthoclase,  and  its  secretion 
from  the  adjacent  rock.* 

§  59.  With  the  feldspar  in  the  above-mentioned  veins 
may  be  compared  the  similar  occurrence,  observed  in  1872, 
in  the  great  quartz  lodes  with  chalcopyrite  which  traverse 
the  Huronian  greenstones  at  the  Bruce  Mines,  on  Lake 
Huron,  of  bands  one  or  two  inches  wide  of  a  brick-red 

* 

#  Geology  of  Canada,  1863;  pp.  470  and  606. 


V 


v.] 


THE   CllENlTIC   HYPOTHESIS. 


128 


ortlioclase,  mingletl  with  a  little  quartz  and  a  small 
ainouiit  of  a  greenish,  apparently  hornblendic  element, 
furming  an  aggregate  which  can  hardly  be  distinguished 
from  some  of  the  older  granitic  rocks,  but  is  clearly  inter- 
banded  with  the  metalliferous  quartz  and  the  bitter-spar 
of  the  lode.  In  this  connection  may  also  be  quoted  a 
description  of  the  vertical  parallel  veins  found  cutting  at 
right  angles  the  Montalbau  gneisses  hi  Northbridge,  near 
Worcester,  Massachusetts.  These  veins,  as  described  by 
the  writer,  "  may  be  traced  iov  considerable  distances,  and 
are  ordinarily  but  a  few  inches  in  thickness.  The  vein- 
stone of  these  is  generally  a  vitreous  quartz,  which  in 
some  parts  exhibits  selvages  and  in  others  bands  of  white 
orthoclase,  by  an  admixture  of  which  it  passes  elsewhere 
into  a  well  characterized  granitic  vein.  The  quartz  veins, 
in  places,  hold  cubic  crystals  of  pyrite,  together  with  chal- 
copyrite  and  pyrrhotite,  the  latter  in  considerable  masses, 
sometimes  accompanied  by  crystals  of  greenish  epidote 
imbedded  in  the  quartz,  and  occasionally  associated  with 
red  garnet.  In  one  part  there  is  found  enclosed  in  the. 
wider  portion  of  a  vein,  between  bands  of  vitreous  quartz, 
a  lenticular  mass  three  inches  thick,  of  coarsely  granular 
pink  calcite,  with  imbedded  grains  of  dark  green  amplii- 
bole,  and  on  one  side  small  crystals  of  olive-green  epidote 
and  red  garnet ;  the  whole  mass  closely  resembling  some 
crystalline  limestones  from  the  Laurentian,"  and  evidently 
endogenous.*  I  have  also  described  remarkable  examples 
of  similar  associations  of  zoisite,  garnet,  hornblende,  pyr- 
oxene, and  calcite  in  the  metalliferous  quartz-lodes  in  the 
Montalban  series,  at  Ducktown,  Tennessee,  f 

§  60.  The  question  of  the  aqueous  origin  of  concretion- 
ary veins  was  resumed  by  the  author  in  1871,  in  an  essay 
On  Granites  and  Granitic  Veinstones,  when  it  was  main- 
tained that  the  relation  of  granitic  veins  with  metalliferous 

*  Azoic  Fiocks,  Report  E,  Second  Geological  Survey  of  Pennsylvania, 
p.  247. 

t  Chemical  and  Geological  Essays,  p.  217. 


■I 


I 


I     I 


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c 


I 


II  •' 


lli! 


r 


124 


THE  ORIGIN  OF  CRYSTALLIITE  ROCKS. 


quartz  lodes,  on  the  one  hand,  and  with  calcareous  veins 
carrying  the  ordinary  minerals  of  crystalline  limestones, 
on  the  other,  is  such  that  to  all  these  veins  must  be 
assigned  a  common  aqueous  origin.  It  was  farther  shown 
that  the  endogenous  granitic  masses  or  veinstones  in 
the  Montalban  or  younger  gneissic  series  in  New  Eng- 
land often  attain  breadths  of  sixty  feet  or  mcne,  and 
that  they  present  great  varieties  in  texture,  from  coarse 
aggregates  of  banded  orthoclase  and  quartz,  often  with 
muscovite  (from  which  these  various  elements  are  mined 
for  commercial  purposes),  to  veins  in  which  the  concre- 
tionary character  is  not  less  marked,  including  beryl,  tour- 
maline, garnet,  cassiterite,  and  other  rare  minerals ;  while 
others  still  of  these  great  veins  are  so  fine-grained  and 
homogeneous  in  character  as  to  have  been  quarried  as 
granites  for  architectural  uses.  These  endogenous  masses 
are  included  alike  in  the  gneisses,  the  quartzites,  the  stau- 
rolitic  mica-schists,  ami  the  indigenous  crystalline  lime- 
stones of  the  Montalban  series,  and,  though  generally 
transverse,  are  sometimes,  for  a  portion  of  their  course, 
coincident  with  the  bedding  of  the  enclosing  rock.* 

It  was  clear  that  these  endogenous  granitic  veins  of 
posterior  origin  were  mineralogically  very  similar  to  the 
older  gneisses  and  the  erupted  granites.  From  a  pro- 
longed study  of  all  these  phenomena,  the  conclusion 
was  then  reached  that  we  have  in  the  action  which  gen-- 
erated  these  endogenous  granitic  rocks  a  coniinuation  of 
the  same  process  wliich  gave  rise  to  the  older  or  funda- 
mental granitoid  gneisses,  which  were  hence  of  aqueous 
origin. 

§  61.  This  process  of  reasoning  was  in  fact  identical 
with  that  by  which  Werner,  in  the  last  century,  was  led 
to  as.sign  an  aqueous  origin  to  the  primitive  granite  and 
the  crystalline  schists.  In  a  description,  in  1874,  of  some 
examples  of  these  banded  veinstones  from  Maine  and  Nova 

•  Amer.  Jour.  Science  (3),  vol.  i.,  pp.  88  aud  182,  and  vol.  ill.,  p.  115; 
also  Cheni.  and  Geol.  Essays,  pp.  183-209. 


▼4 


THE  CUENITIC   HYPOTHESIS. 


125 


Scotia,  it  wan  said  that  their  structure  is  "tluo  to  suc- 
cessive (lepof.its  from  water  of  erystalliiio  matter  on  the 
walls  of  the  /eiu,  and  results  from  a  process  which,  though 
operating  in  later  times  and  in  subterranean  fissures,  was 
probably  not  \ery  much  unlike  that  which  gave  rise  to  the 
indigenous  granitic  gneisses."  *  The  same  ideas  as  to  the 
origin  of  the  ancient  crystalline  rocks,  and  their  relations 
to  granitic  and  to  zeolitic  veins,  were  still  farther  defined 
by  me,  in  1874,  when  it  was  said :  ''The  deposition  of  im- 
mense (quantities  alike  of  orthoclase,  albite,  ind  oligoclase 
in  veins  which  are  evidently  of  aqueous  origin  shows  that 
conditions  have  existed  in  which  the  elements  of  these 
mineral  species  were  abundant  in  solution.  The  relation 
between  these  endogenous  dei'osits  and  the  great  beds  of 
ortlioclase  and  triclinic  feldspar-' ucks  is  similar  to  that 
between  veins  of  calcite  and  of  (|uartz,  and  beds  of  mar- 
ble and  of  travertine,  of  quartzite  and  of  hornstone.  But 
while  the  conditions  in  which  these  latter  mineral  species 
are  deposited  from  solution  have  been  perpetuated  to  our 
own  time,  those  of  the  deposition  of  feldspars  and  many 
other  species,  whether  in  veins  or  in  beds,  appear  to 
belong  only  to  remote  geological  ages,  and,  at  best,  are 
represented  in  more  recent  times  only  by  the  production 
of  a  few  zeolitic  minerals."  f 

§  62.  A  farther  and  more  particularized  statement  of 
the  author's  conclusions  as  to  the  origin  of  the  crystallina 
rocks  was  embodied  in  a  paper  read  before  the  American 
Association  for  the  Advancement  of  Science  at  Saratoga, 
in  August,  1879,  containing  the  three  following  proposi- 
tions :$ — 

"1.  All  gneisses,  petrosilexes,  hornblendic  and  mica- 
ceous scliists,  olivines,  serpentines,  and,  in  short, .all  sili- 
cated  crystalline  stratified  rocks,  are  of  neptunian  origin, 

*  Proc.  Boston  Society  of  Natural  History,  xvi.,  237,  p.  198. 

t  Cliemical  and  Geological  Essays,  p.  298. 

t  The  History  of  Some  Pre-Cambrian  Kocks,  etc.  Proc.  A.  A.  A.  S., 
for  1879,  and  Amer.  Jour.  Science  (1880),  six.,  p.  270.  Also  farther  on, 
Essay  VUI. 


,(1       ^  a 


J>^ 


--ir-vja«^ua-«K;»tai.j 


126 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


PR 


s 


and  are  not  primarily  due  to  metamorphosis  or  to  meta- 
somatosis,  either  of  ordinary  aqueous  sediments  or  of  vol- 
canic materials. 

"  2.  The  chemical  and  mechanical  conditions  under 
which  these  rocks  were  deposited  and  crystallized,  whether 
in  shallow  waters  or  in  abyssal  depths  (where  pressure 
greatly  influences  chemical  affinities),  have  not  been  re- 
produced to  any  great  extent  since  the  beginning  of  paleo- 
zoic time. 

"  3.  The  eruptive  rocks,  or  at  least  a  large  portion  of 
them,  are  softened  ani^  displaced  portions  of  these  ancient 
neptunian  rocks,  of  which  they  retain  many  of  the  min- 
eralogical  and  lithological  characters." 

§  63.  In  a  subsequent  paper,  in  1880,  it  was  said,  with 
reference  to  the  sub-aerial  decay  of  rocks :  "  The  alumi- 
nous silicates  in  the  oldest  crystalline  rocks  occur  in  the 
forms  of  feldspars,  and  related  species,  and  are,  so  to 
speak,  saturated  with  alkalies  or  with  lime.  It  is  only  in' 
more  recent  formations  that  we  find  aluminous  silicates 
either  free  or  with  reduced  amounts  of  alkali,  as  in  the 
argillites  and  clays,  in  micaceous  minerals  like  muscovite, 
margarodite,  damourite,  and  pyrophyllite,  and  in  kyanite, 
fibrolite,  and  andalusite ;  all  of  which  we  regard  as  derived 
indirectly  from  the  more  ancient  feldspars."  In  connec- 
tion with  this  important  point,  which  I  had  already  dis- 
cussed elsewhere,  I  added  the  following  note,  referring  at 
the  same  time  to  the  propositions  of  the  ^receding  para- 
graph :  *  "  It  is  a  question  how  far  the  origin  of  such 
crystalline  aluminous  silicates  as  muscovite,  margarodite, 
damourite,  pyrophyllite,  kyanite,  fibrolite,  and  andalusite, 
is  to  be  sought  in  a  process  of  diagenesis  in  ordinarj'- 
aqueous  sediments  holding  the  ruins  of  more  or  less  com- 
pletely decayed  feldspars.     Other  aluminous  rock-forming 

*  The  Chemical  and  Geological  Relations  of  the  Atmosphere,  ante, 
page  37.  See  farther,  for  the  stratigraphical  relations  of  the  various 
aluminous  silicates  (which  were  first  set  forth  by  the  author  in  1863), 
Chem.  andGeol.  Essays,  pp.  27  and  28;  also  Report  E,  Second  Geological 
Survey  of  Pennsylvania  (1878),  p.  210. 


;l'   •■' 


v.] 


THE  CRENITIC   HYPOTHESIS. 


127 


silicates,  such  as  chlorites  and  magnesian  micas,  are,  how- 
ever, connected,  through  aluminiferous  ampliiboles,  with 
the  non-aluminous  magnesian  silicates,  and  to  all  of  these 
various  magnesian  minerals  a  very  different  origin  must 
be  ascribed." 

In  a  farther  discussion  of  this  subject,  in  1883,  it  was 
noted  "that  decayed  feldspars,  even  when  these  are 
reduced  to  the  condition  of  clays,  have  not,  in  most  cases, 
lost  the  whole  of  their  alkalies."  *  This  was  shown  by 
the  analyses  made  by  Sweet  of  the  kaolinized  granitic 
gneisses  of  Wisconsin,  from  which  it  appears  that  "  the 
levigated  clays  from  these  decayed  rocks  still  hold,  in 
repeated  examples,  from  two  to  three  hundredths  or  more 
of  alkalies,  the  potash  predominating." 

§  64.  The  question  of  the  source  of  the  matters  in 
aqueous  solution,  which,  according  to  the  hypothesis  be- 
fore us,  gave  rise  to  granitic  veinstones,  naturally  comes 
up  at  this  stage  of  our  inquiry.  As  we  have  seen,  the 
granitic  substratum  of  igneous  origin,  the  existence  of 
which  is  postulated  by  most  modern  geologists,  is,  since 
the  time  of  Scrope,  Scheerer,  and  Elie  de  Beaumont,  gen- 
erally conceived  to  be  impregnated  with  a  portion  of 
water,  conjectured  by  Scheerer  to  equal  perhaps  five  or 
ten  hundredths  of  its  weight ;  and  through  the  interven- 
tion of  this  to  assume,  at  temperatures  far  below  the 
point  of  liquefaction  of  the  anhydrous  rock,  a  condition 
which  has  been  designated  one  of  aqueo-igneous  fusion. 
This  interposed  water,  under  the  influence  of  great  heat 
and  pressure,  we  may  suppose,  with  Scheerer,  to  consti- 
tute a  sort  of  "  granitic  juice,"  which,  exuding  from  the 
mass,  might  fill  fissures  or  other  cavities,  alike  in  the 
granite  and  in  the  adjacent  rocks,  with  the  characteristic 
minerals  of  granitic  veins.  This  seems  to  have  been 
essentially  the  view  of  Elie  de  Beaumont,  who  described 
the  elements  of  the  pegmatites,  the  tourmaline-granites, 

*  The  Decay  of  Rocks  Geologically  Considered,  Amer.  Jour.  Science 
(1883),  xxvi.,  194.     Also  post,  Essay  VII.,  §  10. 


I  la  <H 


Hi  V 


128 


THE  ORIGIN  OF   CRYSTALLINE  ROCKS. 


m 


and  the  veins,  often  abounding  in  quartz,  which  cany 
cassiteiite  and  columbite,  as  emanations  from  the  adjacent 
granitic  masses,  or  as  a  "  granitic  aura."  Daubrce  and 
Scheerer,  in  previously  describing  the  similar  granitic  veins 
found  in  Scandinavia,  conceived  them  to  have  been  filled 
in  like  manner,  not  from  an  unstratified  granitic  substra- 
tum, but  from  the  crystalline  schists  which  enclose  them.* 

§  65.  In  both  of  the  above  hypotlieses,  we  note  that 
the  source  of  the  orthoclase  and  the  quartz  of  the  veins  is 
sought  in  the  solutions  derived  from  the  granitic  substra- 
tum or  its  closely  related  crystalline  schists.  If  now  we 
go  farther  back,  and  ask  for  the  origin  of  this  granitic 
substratum,  with  its  constituent  minerals,  we  have  shown, 
in  opposition  to  the  view  that  it  is  the  outer  layer  of  a 
cooling  globe,  good  reasons  for  maintaining,  in  the  first 
place,  that  such  a  la^'-f  must  have  had  a  very  different 
composition  from  that  of  granite,  and  in  the  second  place 
that  granite  itself  is  a  rock  of  secondary  origin,  in  the 
formation  of  which  water  has  in  all  cases  intervened. 
We  have,  moreover,  already  sought  to  show  that  the 
attempt  to  derive  this  granitic  rock,  by  any  process  of 
metamorphosis  or  metasomatosis,  from  sediments  formed 
from  the  primitive  quartzless  rock,  was  untenable,  and 
that  the  vast  granitic  substral  um,  so  homogeneous  and  so 
widely  spread,  could  not  thus  have  originated.  Already, 
in  1874,  it  had  been  declared  that  the  process  which  gen- 
erated the  orthoclase  and  the  quartz  of  the  granitic  rocks 
was  represented  in  more  recent  times  by  the  production 
01  zeolites. 

§  GQ.  The  generation  from  basic  vocks,  by  aqueous 
action,  alike  of  orthoclase,  of  quartz,  and  of  zeolites,  is 
well  known.  These  are  often  associated  in  such  rocks 
under  conditions  which  show  thera  to  be  secretions  from 
the  surrounding  mass.     The  substance  named  palagonite 

*  For  a  general  account  of  the  views  described  in  this  paragraph,  and 
for  references  to  the  somewhat  extended  literature  of  tlie  subject,  see 
Hunt,  Chemical  and  Geological  Essays,  pp.  18S-101;  also  ibid.,  p.  6. 


irol 


v.] 


THE  CRENITIC  HYPOTHESIS. 


129 


is  an  amorphous,  apparently  colloidal,  hydrous  silicate,  the 
composition  of  which,  deducting  the  water  (about  seven- 
teen per  cent  on  an  average),  is,  according  to  Bunsen, 
identical  with  that  of  his  normal  pyroxenic  or  basaltic 
magma  (§  24),  except  that  the  iron  in  palagonite  is  in  the 
state  of  peroxyd.  This  substance  is  changed  by  no  great 
elevation  of  temperature  into  the  zeolite,  chabazite,  a 
crystalline  silicate  of  alumina  and  alkalies,  rich  in  silica, 
but  destitute  of  iron-oxyd  and  magnesia,  and  a  more  basic 
residuum,  in  which  the  latter  two  bases  are  retained. 
Basaltic  rock  is,  according  to  Bunsen's  observations  in 
Iceland,  changed  through  hydration  into  palagonite, 
"under  the  influence  of  a  neptunian  cause,"  and  this,  by 
the  heat  of  contiguous  eruptive  masses,  is  subsequently 
transformed  into  a  zeolitic  amygdaloid.  These  operations, 
as  he  has  shown,  may  be  repeated  in  our  laboratories. 
Fragments  of  amorphous  native  palagonite,  when  rapidly 
heated  in  the  flame  of  a  lamp,  develop  in  their  mass  cavi- 
ties filled  with  a  white  matter,  recognized  by  the  aid  of  a 
lens  as  crystalline  chabazite  ;  while  the  transformation  of 
basaltic  rock  into  palagonite  itself  may  also  be  artificially 
effected.*     Palagonite  is  not,  apparently,  a  distinct  min- 

*  The  following  h  the  composition  assigned  by  Bunsen  to  the  typical 
trachytic  and  basaltic  magmas,  and  to  palagrnite,  as  deduced  from  his 
studies  of  these  rocks  in  Iceland;  A,  being  the  normal  trachytic  type,  the 
mean  of  seven  analyses  of  trachyte  and  obsidian ;  B,  the  normal  basaltic 
type,  from  six  analyses  of  basalt  and  lava;  and  C,  the  average  of  several 
palagonites  of  that  region,  deducting  the  water:  — 


A. 

B. 

C. 

Silica    .... 

.    .    76.67 

48.47 

49.15 

Alumina  .    .    . 

.    .    11.15 

14.78 

30.82 

Ferrous  oxyd     . 

.    .      3.07 

15.38 

Lime    .... 

.      1.45 

1187 

9.73 

Magnesia .    .    .    . 

.      0.28 

6.89 

7.97 

Pjlash.    .    .    . 

.    .      3.20 

0.65 

0.90 

Soda 

.      4.18 

1.96 

1.34 

100.00 


100.00 


100.00 


The  ferrous  oxyd  in  the  six  examples  from  which  B  was  deduced  varied 
from  11.69  to  19.43;  while  for  the  palagonite,  the  iron  (which  is  not  sepa- 


130 


,„E  OlUGm   OF  CKYSTALUNB  BOOKS 


I7» 


e.,  .pee..  ...  a  coUoB.  J;y--l:i-rr^^^^^^^^^^ 
as  marking  a  ^t»g^"^*!^;Tcompounds.  The  crystal- 
Jovm  of  certain  basic  «  "^^*^^^^     ^.ition  may,  however, 

„£  tosic  exoplutonio  '-f>f  ^/te  universal  basic 
have  gone  on  in  the  «  ly  3' J,„„  the  surface  of  the 
,„.V,  which  we  have  ^•^Pr"?^"    ^■^       .,„d  penetrated  by 
.o'.li'^<T  globe,  was  heated  ft"™  ?^'°  ;  ,,hieh,  although  it 
atmospheric  waters  -was  '.~o      j^^_^,^^^,;„g  ^  ^, 
s  emcd  legitimate,  was  too  vaa„^         ^^^^  ^,,,,.  „aiiy 
lightly  accepted.    "  ™\~„a  the  examination  and  , 

yfai-s  of  careful  "^-''^^'^^""ble  hyP°"«^^^' *'''  'T  """I 
Lection  of  all  other  «°ff  ^f '^ese  .■eaetions,  which  give 
.J^tionwas  acquired  that  m  these  ^^^^  ,„i,tion  of 

rise  to  zeolitic  »"'«'-''l=' ^  of  crystalline  rocks.    This 

«,„..  and  is  present  as  fernc 

,  oxyd)  ranged  from  ^.«^^^  ^^,,,  f^r  P^J^-'^^CSd  be  about 
to  24.0  per  cent  '^^^\^J  ,,„^  oxyd,  ll-^-^'/^Se^^Jin,  very  nearly 
of  alumina,  If -9]'  ^^        ^^^  latter  from  the  c..lcui         '       ^^  ^^salt 

tion  of  the  contamed  ^ou^        ^^^^  ^^^^  ^^  ,eol  tes     (o       V  ^^  ^^^^ 

gelatinizes  with  acids  wni>^^      tachvlite-basalts),  and  tne  ny  ^ 

fo  the  vitreous  matter  ofJ^ieU^^^^^  ^  ^-^^^^^?J^ffered  f-m  the 

(1853)  (3)  xxxviii.,  215-iay.) 


v.] 


THE  CRENITIO  HYPOTHESIS. 


131 


globe,  consolidating  at  the  centre,  left  a  superficial  layer 
of  matter  which  has  yielded  all  the  elements  of  the 
earth's  crust.  This  last-cooled  layer,  mechanically  disinte- 
grated, saturated  with  water,  and  heated  by  the  central 
mass,  furnished  in  aqueous  solution  the  silicates  which 
were  the  origin  of  the  ancient  gneisses  and  similar 
rocks."  * 

§  68.  The  transformation  of  the  primary  basic  layer, 
judging  from  the  phenomena  seen  in  basic  exoplutonic 
rocks,  would  give  rise  not  only  to  quartz,  feldspars,  and 
zeolites,  but  to  such  aluminous  silicates  as  prehnite  and 
epidote,  and  to  non-aluminous  silicates  like  pectolite, 
okenite,  and  apophyllite.  These  silicates  are  all  non- 
maguesian,  but  the  reactions  of  many  of  them,  while  in  a 
soluble  condition,  with  dissolved  magnesian  salts  would 
give  rise  to  various  natural  magnesian  silicates,  both 
aluminous  and  non-aluminous. 

§  69.  The  cooling  of  the  surface  of  the  earth  by  radia- 
tion, and  the  heating  from  below,  would  establish  in  the 
disintegrated,  porous,  and  unstratified  mass  of  the  pri- 
mary layer  a  system  of  aqueous  circulation,  by  which 
the  waters  penetrating  this  permeable  layer  would  be 
returned  again  to  the  surface  as  thermal  springs,  charged 
with  various  matters  there  to  be  deposited.  The  result  of 
this  process  of  upward  lixiviation  of  the  mass  would  be 
the  gradual  separation  of  the  primary  undifferentiated 
layer  into  an  upper  stratum,  consisting  chiefly  of  acidic 
silicates,  such  as  feldspars  with  quartz,  and  a  lower,  more 
basic,  and  insoluble  residual  stratum,  charged  with  iron- 
oxyd  and  magnesia;  the  two  representing  respectively 
the  overlying  granitic  and  the  underlying  basaltic  layers, 
the  presence  of  which  beneath  the  earth's  surface  have 
generally  been  inferred  from  exoplutonic  i^henomena. 
The  intervention  of  the  argillaceous  products  of  sub- 
a|3rial  decay  was  considered,  and  the  reactions  between 


*  From  a  repor,       a  lecture  by  the  author  before  the  Lowell  Institute, 
Boston,  Mass.,  Feb.  29,  18S4,  in  the  Boston  Daily  Advertiser  of  March  1. 


132  THE  OKIom  OF  CBVBXALI..^  BOCKS.  *  , 

them  and  mineral  ^"'fZ^Z^Z^l^^-^^'^''"'   '    ■ 
tured,  might  give  nse  to  c^"»     ^^^  j 

s  70.  Tliat  tlie  great  sl>rmKing  ^j  ^^^ 

eolequent  upon  the  re-ov^J-»^{;%  ^,^  „,,,,yi„g 
vast  amount  o£  matter  wtoon  ^^  ^^^ 

;  auitic  ana  gneissic  «e™^;,7„^t.i;i:g  deposit,  and  tl>at 
:  general  corrugation  of  tto  ove   y    S   ^^^^^^^_  ^j^^^^  ^ 

this  would  P''°»'=''l*y''.'',,fw^  magma,  constituting  the 

fissures,  of  the  ^-''"^'y^^.^Zl^^e^e  among  the  most      . 

first  eruptive  or  ^^»f  "'"^Jhyp^thesis.     These  various 
Obvious  deductions  fom  this  W       ^^^^^  ^^^  ;„  April 

points  were  ~°:;;^tlhthf  suggestion  that  this  nevvly 
Ld  May  of  1884  with  the  sugg  ^^  ^  ^^^^.^^  ^^^^s, 
proposed  explanation  of  the  o  g  ^^    ^,„     i 

.     Lough    the    ac  ion    o    J^/<,,u,a  the  ceesihc  hy- 
matters  from  below,  might  «  ^^         g , 

pothesis, from  the  Greek J^'J.^ ^^gical  ^.^^^^  „f  the 
§  "•  Tl;'  -flhi*  !e  have  BketcLd  in  the  preceding 

"^^^-^tZ^Z::^  doctrine  of 
^  I.  -1858.  An  attempt  to  deduce  .^^^ 

a  solid  incandescent  — 'J^tle^s^^^  'asic,  through 
ous  rock,  supposed  *"  jl' J^V  ,  t^,,  jutinct  and  un- 
niechanical  and  't^era'^^^g^^^^^;;,  ^hjch,  when  subse- 
liUe  classes  of/ed'^^^f  ^  ^rrane^n  heat,  should  give 
quently  transformed  by  «""*"*  ^^^^^^  rocks.  This 
le  two  types  of  acidic  and  ^s'" -^^^^^i^  nietamorphro 
woB  an  attempt  to  »d^*  *he  ^4  ,„ 

silicates.  »„,^nt  to  extend  this  last  conception 

^    111.-1863.  An  attempt  to  ex  ^^^^^^  ^ 

.  on  ««  Origin  o.  'h«  C^^"-  ^:rica?N.tur.U..  .or  ^-=; 


i' 


v.] 


THE  CRENITIC  HYPOTHESIS. 


133 


e 
g 

e- 

h 

in- 


36- 

ve 
his 
hie 
to 

by 

tyd- 

tion 

ly  of 
June; 
ience, 


to  double  aluminous  silicates,  by  a  consideration  of  the 
formation  of  zeolites  at  the  earth's  surface  in  rocks  of 
secondary  age,  and  also  in  more  recent  times,  through  the 
action  of  thermal  waters ;  it  being  shown,  from  the  asso- 
ciation of  zeolites  with  feldspar  and  quartz  in  nature,  tiiat 
all  these  are  sometimes  formed  contemporaneously  from 
aqueous  solutions,  and  also  that  many  feldspathic  veins 
and  masses  have  probably  had  a  similar  aqueous  origin. 

IV.  — 1871.  The  subject  of  granite  veins  farther  dis- 
cussed, and  the  mineralogical  similarity  between  these 
endogenous  masses  and  the  indigenous  gneissic  and  gran- 
itic rocks  insisted  upon. 

V.  — 1874.  The  argument  reiterated  that  the  condi- 
tions under  which  the  primitive  granitic  and  gneissic 
rocks  had  been  produced  were  essentially  similar  to  those 
of  the  granitic  veins  of  the  later  crystalline  schists,  and 
that  these  conditions  are  reproduced  to  a  smaller  extent, 
in  later  times,  in  the  formation  of  zeolitic  minerals: 
finally,  that  the  gneisses  and  bedded  granites  are  to  gran- 
itic veins  what  beds  of  chemically-deposited  limestone  and 
travertine  are  to  calcareous  veins. 

VI.  — 1880.  The  definite  assertion  of  the  aqueous 
origin  of  stratified  crystalline  rocks,  coupled  with  the 
rejection  of  the  doctrines  of  metamorphisra  and  meta- 
somatism in  explaining  their  origin,  and  the  assertion  of 
their  pre-paleozoic  age.  At  the  same  time,  the  probable 
intervention  of  clays  from  the  sub-aerial  decay  of  feld- 
spars, as  a  source  of  certain  crystalline  aluminous  silicates 
is  suggested. 

VII.  — 1884.  The  definite  assertion  is  made  that  the 
ancient  crystalline  rocks  were  generated  either  directly 
from  materials  brought  to  the  surface  by  subterranean 
springs  from  the  primary  igneous  rock,  or,  as  was  the  case 
in  later  times,  by  the  reactions  of  these  materials  with  the 
products  of  sub-aerial  decay.  These  latter  included  clays 
from  feldspars,  and  dissolved  magnesian  salts  formed  by 
the  action  upon  sea-wate^'  of   magnesian  carbonate  set 


i 


m  m 


n  m 


184 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


tv. 


li   t. 


free  in  the  atmospheric  decomposition  of  basic  rock  erup- 
ted from  tlie  primary  stratum.  Thus,  while  what  may  be 
called  the  Primitive  crystalline  rocks  were  wholly  crenitic 
in  their  origin,  the  soluble  and  insoluble  results  of  the 
sub-aerial  decay,  alike  of  basic  exoplutonic  matter  and  of 
the  older  crenitic  rocks,  contributed  to  the  formation  of 
the  later  or  Transition  crystalline  schists. 

III.  —  ILLUSTRATIONS  OF  THE  CRENITIC   HYPOTHESIS. 

§  72.  The  crenitic  hypothesis,  which  has  been  proposed 
in  the  second  part  of  this  essay  to  account  for  the  origin 
of  the  granites  and  crystalline  schists,  conceives  them  to 
have  been  derived,  directly  or  indirectly,  by  solution  from 
a  primary  stratum  of  basic  rock,  the  last  congealed  and 
superficial  portion  of  the  cooling  globe,  through  the  inter- 
vention of  circulating  subterranean  waters,  by  which  the 
mineral  elements  were  brought  to  the  surface.  This  view 
not  only  comjiares  the  generation  of  the  constituent 
minerals  of  the  primitive  rocks  with  that  of  the  minerals 
formed  in  the  basic  eruptive  rocks  of  later  times,  but 
supposes  these  latter  rocks  to  be  extruded  portions  of  the 
primary  plutonic  stratum  which,  though  more  or  less 
modified  by  secular  changes,  still  exhibit  after  eruption, 
though  on  a  limited  scale,  the  phenomena  presented  by 
that  stratum  in  remoter  ages.  The  study  of  these  rocks, 
^nd  of  their  accompanying  secondary  minerals,  which 
may  be  properly  described  as  the  secretions  of  these  rocks, 
will  therefore  be  found  very  important  as  illustrations  of 
the  crenitic  hypothesis. 

§  73.  Without  here  entering  into  the  details  of  their 
geognosy  or  their  lithology,  it  is  sufficient  to  recall  the 
fact  that  such  basic  eruptive  rocks  abounding  in  zeolitic 
minerals  are  found,  with  many  characters  in  common,  from 
the  time  of  the  Cambrian  or  pre-Cambrian  Keweenian 
series  of  Lake  Superior  to  that  of  the  trias  of  eastern 
North  America,  the  tertiary  of  Colorado  and  the  British 
Islands,  and  the  recent  lavas  of  Iceland.    The  secreted 


v.] 


THE  CRENITIC   HYPOIHESIS. 


135 


minerals  of  these  rocks  often  occur  in  closed  cavities  in 
tufaceous  beds,  constituting  amygdaloids,  and,  at  other 
times,  in  veins  or  fissures  of  considerable  size.  They  are 
not,  however,  confined  to  the  tufaceous  or  recomposed 
detrital  exoplutonic  rocks  (which  are  sometimes  them- 
selves hydrated  and  transformed  into  palagonite,  as  de- 
scribed by  Bunsen  in  Iceland),  but  occur  in  veins  and 
cavities  in  massive  rocks,  as  is  well  seen  in  the  diabasu  of 
Bergen  Hill,  New  Jersey,  and  the  massive  basalt  of  Table 
Mountain,  near  Denver,  Colorado,  both  remarkable  for 
their  zeolitic  minerals. 

§  74.  The  accumulations  of  secreted  minerals  in  these 
conditions  are  often  considerable  in  amount.  Among 
other  examples,  it  may  be  noticed  that  the  zeolitic  masses 
in  the  amygdaloids  of  the  Faroe  Islands  are  sometimes 
three  or  four  feet  in  diameter,  and  constitute  a  large  por- 
tion of  the  rock.  Veins  of  laumontite  in  Nova  Scotia 
attain  breadths  of  a  foot  or  more,  while  some  veins  on 
Lake  Superior,  which  are  made  up  to  a  great  extent  of 
zeolitic  and  related  species,  are  two  and  three  feet  or  more 
in  breadth,  and  often  of  considerable  extent.  The  history 
of  the  chemical  composition  of  the  zeolite-bearing  rocks 
of  Lake  Superior,  and  of  the  changes  which  hi,ve  taken 
place  in  their  degradation  from  the  original  eruptive  mass, 
have  been  studied  in  detail  by  Pumpelly,  with  the  help  of 
the  previous  analyses  of  Macfarlane,  but  cannot  here  be 
discussed.*  .  - 

§  75.  We  may  here  notice  the  modes  of  occurrence  of 
the  zeolites  of  Table  Mountain,  Colorado,  as  described  in 
1882  by  Messrs.  Cross  and  Hildebrand.f  The  upper  forty 
feet  of  a  great  flow  of  basalt,  one  hundred  feet  or  more 
in  thickness,  show  many  cavities,  large   and  small,  de- 

*  T.  Macfarlane,  Geological  Survey  of  Canada,  1866,  pp.  149-164; 
Pumpelly,  Geology  of  Michigan,  1872,  part  2;  also  the  same,  on  The 
Metasomatic  Development  of  the  Copper-bearing  Rocks  of  Lake  Supe- 
rior, Proc.  Amer.  Acad.,  Boston  (1876),  vol.  xiii.,  pp.  253-309. 

t  Cross  and  Hildebrand,  American  Journal  of  Science,  xxiii.,  452, 
and  xxiv.,  129. 


r 


136 


THE  ORIGIN  or  CUYSTALLINB  liOCKS. 


[v; 


•.;!y: 


!i;;l 


scribed  as  more  or  less  flattened  and  drawn  out.  Some  of 
these  cavities  are  empty,  wliile  others  a'o  more  or  less 
completely  filled  by  various  zeolites,  which  are  also  found 
in  fissures  m  the  mass  and,  in  the  case  of  analcite,  in  a  < 
conglomerate  made  up  of  pebbles  of  basic  eruptive  rocks, 
underlying  the  bed  of  basali",  The  zeolitic  deposit  often 
appears  as  "a  reddii'.h-yellow  sandstone-like  material, 
which  occurs  in  many  of  the  cavities.  In  the  larger  ones 
it  takes  the  form  of  a  floor,  the  upper  surface  being  hori- 
zontal, and  the  deposit  may  be  several  inches  in  thickness. 
Small  cavities  have  been  completely  fllled  with  it,  and 
it  is  clear  that  the  deposition  has  taken  place  from  the 
bottom  of  each  cavity,  upward.  In  parts  of  Sorth  Table 
Mountain,  especially,  the  same  material  has  filled  fissures. 
Usually  the  lower  part  of  such  masses  is  composed  of  a 
reddish-yellow  mineral  in  irregular  grains,  which  form  a 
compact  aggregate,  in  which  lie  isolated  spherules  of 
a  similarly  colored  radiated  mineral.  These  spherules  are 
seldom  more  than  two  millimetres  in  diameter,  and  are 
very  perfect  spheres.  They  increase  in  number  upwards, 
and  finally  form  the  greater  part  of  the  deposit.  In  one 
cavity,  six  or  eight  feet  in  horizontal  diameter  and  about 
two  feet  high,  the  deposit  is  quite  different.  Here  the 
main  mass  is  loosely  granular,  and  is  formed  chiefly  by  a 
bright  greenish-yellow  mineral,  while  a  stratified  appear- 
ance is  produced  by  layers  of  a  white  or  colorless  mineral. 
Some  of  the  white  layers  are  chiefly  made  up  of  easily 
recognized  stilbite,  and  the  same  mineral,  in  distinct 
tablets,  forms  the  upper  layer  of  the  whole  deposit. 
There  are  also  irregular  seams  of  white  running  through 
the  yellow  mineral."        „ 

The  greenish-yellow  crystalline  mineral  was  found  to 
consist  of  laumontite,  and  the  other  layers  were  mixtures 
of  stilbite  and  laumontite,  with  some  of  which  were  found 
spherules  of  thomsonite.  This,  in  other  cavities,  formed 
layers  by  itself,  without  admixture  of  the  other  zeolites 
mentioned.     The  presence  of   these  zeolites  in   cavities 


01 


■I  - 


▼0 


THE  CRENITIC  HYPOTHESIS. 


137 


side  by  side  with  other  cavities  v.hich  were  entirely  empty, 
is,  according  to  the  writers  whom  we  have  quoted,  appar- 
ently due  to  the  fact  that  the  former  communicated  witli 
fissures  which  were  channels  for  the  percolating  waters  that 
deposited  the  zeolites.  Such  fissures,  filled  up  with  similar 
zeolites,  were  in  many  cases  found  leading  to  these  cavities. 
§  76.  The  eruptive  rocks  which  break  through  the 
Trenton  (Ordovician)  limestone  at  and  near  Montreal,  in 
Canada,  are  of  various  ages  and  unlike  composition. 
Some  of  these  are  highly  basic,  and  have  been  described 
as  dolerites  and  diorites,  while  some  have  been  found  to 
contain  analcite,  and  others  again  much  nephelite,  and 
have  been  refei'red  +,o  teschenite  and  nepheline-syenite. 
In  some  fine-grained  amygdaloidal  varieties  of  these  basic 
rocks,  which  have  been  designated  dolerites,  I  long  since 
described  the  occurrence  of  heulandite,  chabazite,  anal- 
cite, and  natrolite,  with  quartz  and  epidote.*  These  zeo- 
lites are  not  abundant,  but  in  certain  of  the  basic  doleritic 
rocks  on  Mount  Royal  I  have  found  remarkable  veins  of 
orthoclase  with  quartz  and  other  minerals,  which  merit  a 
notice  in  this  connection.  Included  in  veitical  dikes  of 
these  rocks,  themselves  cutting  the  horizontal  limestones 
which  appear  at  the  base  of  the  mountain,  are  frequent 
granitic  veins,  sometimes  twelve  inches  or  more  in 
breadth,  parallel  with  the  walls  of  the  inclosing  dike, 
often  distinctly  banded,  and  exhibiting  a  bilateral  sym- 
metry which,  together  with  their  drusy  structure,  shows 
them  to  be  endogenous.  The  most  characteristic  of  these 
veins  are  made  up  of  white,  coarsely  crystalline  orthoclase 
with  a  little  quartz  which,  in  druses,  presents  pyramidal 
forms.  In  somo  of  the  veins.  Dr.  Harrington  has  since 
detected,  besides  orthoclase  and  quartz,  nephelite,  sodalite, 
cancrinite,  amphibole,  acmite,  biotite,  and  magnetite.  All 
of  these  minerals  are  seemingly  secretions  from  the  en- 
closing basic  exotic  rock. 

*  Hunt,  in  Geology  of  Canada,  1863,  pp.  441,  655,  and  668;  also  Har- 
rington, Report  Geol.  Survey  of  Canada,  1877-78,  p.  43,  G. 


r 


m 


*■! 


I 


m 


138 


THE  ORIGIN   OP  CRYSTALLINE  ROCKS. 


[V. 


§  77.  The  mineral  secretions  of  tlio  basic  eruptive 
rocks  may  bo  conveniently  grouped  under  seven  heads,  as 
follows :  — 

1.  The  aluminous  silicates,  including  the  zeolites  prop- 
erly so  called,  to  which  we  append  the  related  hydrous 
species,  prehnite,  and  the  associated  species,  orthoclase, 
garnet,  and  epidoto,  which  are  found  in  the  amygdaloidal 
rocks  of  Lake  Superior.  To  these  we  must  add  albite, 
axinite,  tourmaline,  and  sphene,  observed  by  Emerson,  in 
1882,  in  a  diabase  dike  in  the  trias  at  Deerlield,  Massa- 
chusetts,* and  also  the  various  aidiydrous  aluminous  sili- 
cates found  with  orthoclase  in  the  veins  on  Mount  Koyal, 
just  described. 

2.  The  group  of  hydrous  protoxyd-silicates,  the  bases 
of  which  are  lime  and  alkalies,  and  of  uiiich  pectolite  may 
be  taken  as  the  type.  These  8i)eeies  are  sometimes 
wrongly  spoken  of  as  belonging  to  the  class  of  zeolites. 
As  an  appendage  to  this  group,  we  note  the  hydrous  boro- 
silicate  of  lime,  datolite,  frequently  found  in  these  rocks. 
Mention  should  here  also  be  made  of  the  anhj^drous  pro- 
toxyd-silicates, amphibole  and  acmite,  in  the  feldspathic 
veins  of  Mount  Royal.  We  have  already  called  attention 
to  the  occurrence  of  amphibole  and  pyroxene  in  granitic 
veins  under  other  conditions  (§  57). 

8.  Quartz  in  its  various  crystalline  and  cryptocrystal- 
line  forms,  as  rock-crystal,  amethyst,  chalcedony,  agate, 
and  jaspery  varieties,  is  found  both  alone  and  associated 
with  the  minerals  of  the  preceding  groups.  Hyalite  of 
very  recent  origin  has  also  been  observed  by  Emerson  at 
Deerfield. 

4.  The  oxyds,  magnetite  and  hematite,  are  frequent  in 
the  zeolite-bearing  rocks  of  Nova  Scotia,  where  both  of 
these  species  form  /eins  in  amygdaloid,  and  where  mag- 
netite moreover  occurs  in  drusy  cavities  with  quartz,  lau- 

*  Emerson,  Amer.  Jour.  Science,  xxlv.,  pp.  195,  270,  and  329.  We  re- 
serve for  another  occasion  the  discussion  of  tlie  paragenesis  of  the  min- 
erals of  this  locality,  so  carefully  studied  by  Emerson. 


v.] 


THE   CUENITIC    HYP0TIIi:SI8. 


189 


of 
at 

in 

of 


inontito,  and  calcito.  Homntito,  in  tho  form  of  plates  of 
specular  ore,  is  also  found  there  in  veins  with  lauinontite, 
and  niangiinese-oxyd  is  sometimes  associated  with  these 
iron-oxyds.  Small  crystals  of  hematite  on  prehnite,  with 
a  little  niiiiiganese-oxyd,  have  been  observed  by  Emerson 
at  the  Deerfield  locality,  as  also  cuprite  on  datolite,  and 
malachite  on  prehnite.  In  bimilar  associations  lie  found 
moreover  small  portions  of  various  sulphids,  such  as  chal- 
copyrite,  pyrite,  sphalerite,  and  galenite.  (ylnfe.page  121.) 

5.  The  presence  of  native  co[)per,  and  occasionally  of 
native  silver,  associated  with  the  various  silicates  already 
named,  should  also  be  noticed.  The  former  metal  is  com- 
mon to  the  zeolitic  rocks  of  Lake  Superior  and  Nova 
Scotia. 

6.  Mention  should  here  be  made  of  the  saponite  often 
found  in  amygdaloidal  rocks,  which,  in  its  purer  form,  is  a 
hydrous  silicate  of  magnesia  with  but  little  alumina  or 
iron-oxyd.  Matters,  apparently  of  this  class,  fill,  or  more 
frequently  line,  amygdaloidal  cavities  which  are  filled  with 
other  species.  This  magnesian  hydrous  silicate  is  per- 
haps distinct  in  origin  from  the  delessite  or  iron-chlorite 
which  is  a  frequent  constituent  of  many  basic  rocks,  such 
as  the  melaphyres  of  Lake  Superior,  and  is  probably  not  a 
secretion  but  a  residual  product  of  the  transformation  of 
the  rock.  . 

7.  Calcite  in  various  forms  is  a  common  species  in  the 
rocks  in  question,  and  fluorite  and  barytine  may  also  be 
mentioned  as  accidental  minerals  therein. 

It  is  principally  with  *he  first  two  classes  of  minerals, 
the  zeolitic  group  with  its  appendages,  and  the  pectolitic 
group  that  we  have  to  do.  These  two,  as  is  well  known, 
though  chiefly  found  in  the  eruptive  rocks  already  noticed, 
are  not  confined  to  them.  Some  species  of  zeolites  occur 
occasionally  in  veins  in  gneiss  and  other  crystalline  rocks, 
aild  even  in  limestones  and  other  sedimentary  deposits. 
These  occurrences  are  the  more  readily  understood  when 
we  consider  that  the  same  minerals  have  in  various  locals 


Hi 


'ill 


mamm 


>.  |!(.  I  'L.^miLm^it^mimmaii'mgimmtmmmi 


Hlf'M 


li 


140 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


[V. 


ties  been  recently  formed  by  the  action  of  thermal  waters, 
and  are  even  generated  iu  submarine  ooze.  Many  of  the 
species  of  these  two  groups  have  also  been  formed  artifi- 
cially in  the  chemist's  laboratory. 

§  78.  It  is  our  present  purpose  to  consider,  first,  the 
zeolitic,  and  secondly,  the  pectolitic  group,  both  as  regards 
their  chemical  composition  and  their  relations  to  various 
anhydrous  silicates.  We  shall  then  proceed  to  notice  the 
action  of  water  at  high  temperatures  on  glass  and  similar 
bodies,  in  giving  rise  to  various  crystalline  species,  includ- 
ing quartz.  In  this  connection  will  also  be  discussed 
some  facts  relating  to  the  chemistry  of  tne  alkaline  sili- 
cates. We  shall  next  notice  the  action  of  thermal  waters 
in  historic  times,  aiiv'  the  occurrence  of  zeolites  in  the 
clays  of  the  deep  sea,  and  then  pass  to  the  experiments  on 
the  artificial  reproduction  of  zeolitic  species  in  the  labora- 
tory of  the  chemist,  and  discuss  the  relations  of  hydrous 
and  anhydrous  species.  From  this,  we  shall  proceed  to  a 
consideration  of  the  reactions  of  the  hydrous  species  of 
the  two  groups  with  magnesian  s?its.  The  origin  of  these 
salts  through  sub-aerial  decay  of  exoplutonic  magnesia- 
bearing  silicates,  and  their  relation  to  the  primeval  sea, 
will  then  claim  our  notice ;  after  which  will  be  considered 
the  probable  relations  of  the  clays  from  the  sub-aerial 
decay  of  feldspathic  rocks  to  other  classes  of  rock-making 
silicates.  The  conditions  of  crystallization  of  mineral 
matter  will  next  be  considered  in  relation  to  the  formation 
of  rocks,  after  which  the  conclusions  of  our  present  study 
will  be  briefly  summed  up  in  the  fourth  and  last  part  of 
this  essay. 

§  79.  In  the  accompanying  table  of  zeolites  and  related 
species,  are  placed,  in  the  first  column,  the  names  of 
hydrous  species,  and  in  the  second  column  the  ox3'gen- 
ratios  between  the  protoxyd-bases,  the  alumina,  the  silica, 
and  the  water,  represented  respectively  under  R,  r,  Si,  and 
H.  In  the  fourth  column  are  given  the  names  of  corre- 
sponding anhyd'  ous  species.     In  this  and  the  succeeding 


V.1 


THE  CEENITIC   HYPOTHESIS. 


141 


TABLE  OF  ZEOLITES  AND  BELATED  SPECIES. 


HYDRO0S.                      E :  r :  SI  :  H             R 

Anhydeous. 

Thomgonite   ...... 

1:3:4:2 

Ca,  Ka. 

Anortbite,etc. 

Oismondite 

1 :  3  :  4i  :  4} 

Ca. 

Nephelite. 

Fsmarkite 

Fahlunlte 

1:3:5:1 
1:3:5:2 

Mg. 
Mg. 

Barsowite, 
lolite,  eto. 

Natrolite 

Scolecite 

Mesolite 

Levynlte 

1:3:6:2 
1:3:6:3 
1:3:6:3 
1:3:6:4 

Na. 
Ca. 

Ca,  Na. 
Ca,  Na. 

Labradorlte. 

Analcite 

Kudnopliite 

Laumontite 

Herachclite 

PhiUipsite 

Ckabazite 

Gmelinite 

1:3:8:2 
1:3:8:2 
1:3:8:4 
1:3:8:5 
1:3:8:5 
1:3:8:6 
1:3:8:6 

Na,  Ca,  K. 

Na. 

Ca. 

Na,K. 

Ca.K. 

Ca,  Na,  K. 

Ca,  Na. 

Andesite, 

Hyalophane, 

Leuoito. 

* 

Faujasite 

Hypo8tilbite 

Puflerite 

1:3:9:6 
1:3:9:6 
1:3:9:6 

Ca,  Na. 
Ca,  Na. 
Ca. 

Oligoclase. 

Harmotome 

1  :  3 :  10  :  6 

Ba. 

? 

Heulandite 

EpiBtilbite 

Brewsterite   ...... 

Stilbite 

1  :  3  :  12  :  6 
1  :  3  :  12  :  5 
1  :  2  :  12 :  6 
1  :  3  :  12  :  6 

Ca. 
Ca. 

Ba,  Sr. 
Ca. 

Orthoclase, 
Microoline, 
Albite. 

Prehnite 

2:3:6:1 

Ca. 

? 

Jollyte 

1:2:3:2 

Mg,  Fe. 

ZoiHito,  eto. 

:f    ' 


ywaw— 


142 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


[V. 


tables  I  have  generally  followed  the  terminology  and 
adopted  the  formulas  given  in  the  fifth  edition  of  Dana's 
"System  of  Mineralogy." 

In  the  line  with  the  most  basic  zeolite  known,  thom- 
sohite,  is  placed  the  feldspar,  anorthite,  and  with  nephe- 
lite  is  coupled  the  hydrous  species  gismondite,  a  true 
zeolite.  The  recent  analyses,  by  Cross  and  Hildebrand, 
of  the  zeolites  of  Table  Mountain,  Colorado,  give  for  the 
zeolites  having  the  characters  of  thomsonite  a  proportion 
of  silica  greater  than  corresponds  to  the  formula  of  that 
mineral  given  by  Rammelsberg,  which  we  have  placed  in 
the  table.  Some  of  their  analyses,  while  yielding  almost 
exactly  the  other  ratios  of  the  formula,  give  for  silica, 
instead  of  4.0C  the  numbers,  4.65,  4.76,  and  even  5.17 ; 
showing  a  composition  more  silicious  than  that  of  gismon- 
dite, and  approaching  that  of  a  zeolite  corresponding  to 
fahlunite,  barsowite,  and  bytownite.  These  chemists, 
while  believing  the  specimens  analyzed  by  them  to  repre- 
sent a  pure  and  unmixed  mineral,  leave  undecided  the 
question  of  its  real  composition. 

§  80.  The  feldspar  which  has  been  called  barsowite 
and  bytownite,  according  to  several  concordant  analyses 
is  as  distinct  from  anorthite  .s  it  is  from  labradorite,  and 
apparently  as  much  entitled  to  form  a  distinct  species 
as  the  latter  feldspar,  or  as  andesite  or  oligoclase.  The 
composition  of  a  lime-barsowite,  with  the  ratios,  1:3:5, 
would  be  silica  48.54,  alumina  33.33,  and  lime  18.13  = 
100.00.  With  barsowite  has  been  placed  iolite,  which  is 
a  magnesia-iron  silicate,  giving  the  above  ration,  and,  as 
I  long  since  pointed  out,  is  from  its  atomic  volume  enti- 
tled to  be  regarded  as  a  feldspathide.  These  various 
anhydrous  species  would  appear  to  correspond  very 
nearly  with  the  so-called  thomsonite  of  Cross  and  Hilde- 
brand. With  this  anhydrous  group  we  have  placed  two 
hydrous  magnesian  species,  the  one,  esmarkite,  also  called 
praseolite  and  aspasiolite,  and  the  other  fahlunite,  which 
includes  what  have  been  called  auralite  and  bonsdorffite. 


and 

i 

hyc 

thej 

dial 

spoj 

COM 


Joii 


v.] 


THE  CRENITIO   HYPOTHESIS. 


143 


These  species  are  often  associated  in.  nature  with  iolite, 
from  which  they  differ  only  in  the  presence  of  Avater,  and 
they  have  been  by  most  minerak)gists  regarded  as  formed 
by  subsequent  hydration  from  this  mineral.  This  view, 
however,  was  contested  by  Scheerer,  who  regarded  the 
association  of  the  hydrous  and  anhydrous  minerals  as 
due  to  a  simultaneous  crystallization  of  two  isomorphous 
species.* 

The  relations  of  the  silicates  of  the  natrolite  section  to 
labradorite  are  obvious  from  the  table.  The  same  may 
be  said  of  the  relations  of  the  numerous  silicates  of  the 
analcite  section  to  andesite,  hyalophane,  and  leucite,  and 
of  the  faujasite  section  to  oligoclase.  It  is  to  be  noted 
that  the  well-defined  zeolite,  harmotome,  has  as  yet  no 
corresponding  anhydrous  silicate.  Of  the  heulandite  sec- 
tion, and  the  corresponding  feldspars,  orthoclase  and  al- 
bite,  it  is  to  be  remar!:ed  that  orthoclase  and  albite  are 
the  only  feldspars  hitherto  found  associated  with  zeolites, 
and  the  only  feldspars  as  yet  artificially  produced  in  the 
wet  way.  The  observations  of  Whitney  already  noticed 
(§  57)  have  since  be.en  fully  confirmed  by  Pumpelly,  who 
finds  orthoclase  very  common  with  the  zeolitic  minerals 
on  Lake  Superior,  where  its  deposition  is  shown  to  be 
posterivjr  to  laumontite,  prehnite,  analcite,  apophyllite, 
quartz,  calcite,  copper,  and  datolite ;  the  only  species 
superimposed  upon  it  being  calcite,  chlorite,  and  epidote, 
which  latter  also  occasionally  occurs  between  laumontite 
and  prelmite  in  order  of  superposition,  f 

§  81.  We  have  placed  at  the  end  of  the  table  the  two 
hydrous  silicates,  prelmite  and  jollyte,  though  neither  of 
them  presents  the  ratios  for  protoxyds  and  alumina  which 
characterize  the  zeolites.  Prehnite  has  no  known  corre- 
sponding anhydrous  silicate,  while  jollyte,  though  a  less 
common  species,  is  interesting  inasmuch  as  it  affords  the 


I 


.;£■ 


■\i. 

:•  i. 


*  Amer,  Jour.  Science  (1848),  v.  385,  from  Pogg.  Annalen,  Ixviii.,  319. 
t  See  Pumpelly,  Geology  of  Michigan,  already  cited,  §  74;  also  Amer. 
Journal  Science  (1871),  ill.,  254. 


in 


ill 

I 


THE  ORIGIN  OF  CBYSTALI-INE  ROCKS. 


tv. 


Ill   I 


oxygen-ratios  of  the  anhydrous  zoisite  and  th°i  nearly 
anhydrous  species  epidote.  It  has  also  the  o'cygen-ratios 
of  meionite  of  the  scapolite  group,  an  anhyd)0U8  silicate 
which,  however,  belongs  to  a  much  less  coudensed  ^^ype 
than  zoisite,  as  is  indicated  by  its  inferior  density  and 
hardness,  and  its  ready  decomposition  by  acids.  I  have 
elsewhere  discussed  the  relations  of  these  two  silicates, 
and  have  shown  that  the  density,  hardness,  and  chemical 
indifference  of  epidote  and  saussurite  assign  them  a  place 
with  garnet  and  idocrase,  in  the  grenatide  group  ;  while 
meionite,  though  lacking  the  proper  feldspar-ratio  between 
protoxyds  and  alumina,  belongs  to  the  feldspathides.* 
[The  recent  conclusions  of  Tschermak  as  to  the  oxygen- 
ratios  of  the  scapolites  are  set  forth  in  Essay  VIII.,  on 
"A  Natural  System  in  Mineralogy,  etc.,"  §  75-78,  in 
which  essay,  under  Tribes  6,  7,  and  8,  will  be  found  dis- 
cussed at  length  the  chemical  constitution  and  history  of 
the  principal  aluminous  double  silicates  here  noticed.] 

§  82.  It  is  to  be  noted  that  the  p.rotoxyd-bases  of  the 
zeolites  and  their  related  feldspathides  are  either  alkalies 
or  lime,  baryta  or  strontia,  ii  we  except  the  partially 
magnesian  zeolite,  picrothomsonite,  and  iolite  and  some 
related  hydrous  species,  which,  besides  magnesia,  include 
ferrous  oxyd.  The  latter  base  enters  also  to  some  extent 
into  epidote  and  prehnite.  It  should  also  be  remarked 
that  small  portions  of  ferric  oxyd  are  frequently  found  in 
the  analyses  of  zeolites,  amounting,  in  the  red  varieties  of 
laumontite  to  three  or  four,  and  in  some  natrolites  to  one 
and  two  hundredths.  Some  part  of  this,  however,  is  dis- 
seminated in  the  form  of  hematite,  giving  color  to  the 
zeolites,  and  recalling  the  association  alike  of  hematite 
and  magnetite  with  zeolites,  as  already  noticed,  as  also  a 
similar  occurrence  of  these  oxyds  crystallized  in  many 
granitic  veins. 

§  83.  We  next  come  to  the  hydrous  silicates  of  lime 
and  alkalies,  which  we  have  called,  for  convenience,  the 

*  Chemical  and  Geological  Essays,  pp.  445-447. 


TJ 

its 
fenoi 
and 
secoi 


ill 


lii'ii  I 


y.j 


THE  CRENITIC  HYPOTHESIS. 


145 


pectolitic  group,  and  which  are  correlated  in  the  accom- 
panying table  with  other  protoxyd-silicates  having  similar 
oxygen-ratios,  chiefly  magnesian,  and  partly  hydrated  and 
partly  anhydrous.  We  have  indicated  in  the  second 
column,  for  the  known  silicates  of  the  pectolitic  group, 
the  oxygen-ratios  of  R,  Si,  and  H,  as  in  the  former  table, 
and  have  left  a  blank  under  H,  where,  as  in  the  first 
three  terms,  for  example,  no  nou-maguesian  species  is 
known. 

TABLE  OF  PROTOXYD  SILICATES. 


Pectolitic.          R  :  SI :  H 

4:3:- 

Chondrodite,  Humite,  etc. 

?     .    .    . 

1:1:  — 

Chrysolite,  Monticellite,  Phenaclte,  etc. 

?    .    .    . 

3:4:  — 

Serpentines,  Leucophanite. 

Gyrollte,  etc.    . 

2:3:1 

Deweylite,  Genthite. 

Xonaltite     .    . 
Plomblerite     . 

1:2:  J 
1:2:2 

WoUastonite,  Amphibole,  Rhodonite, 
Pyroxene,  Enstatite,  Cerolito. 

Pectollte .    .    . 

6  :  12  : 1 

Amphibole  in  part,  Spadaite. 

?    .    .    . 

2:6:  - 

Talc  in  pa. 

?    .    .    . 

1:3:  — 

Sepiollte,  Talc  in  part. 

(Unnamed)  .    . 
Okeuite    .    .    . 
Apophyllite     . 

1:4:  J 
1:4:2 
1:4:2 

Titanite,  Ouarinite. 

The  first  place  in  the  table  is  given  to  chondrodite,  with 
its  sub-species,  the  most  basic  natural  protoxyd-silicates 
known,  and  remarkable  for  the  replacement  of  a  small 
and  variable  proportion  of  oxygen  by  fluoriuQ.  In  the 
second  line,  besides  the  chrysolites  (including  the  pure 


yj    I'l 


.  ni^IGlN  OF  CEYSTAI^M  BOCKS.  tV. 

il6  THE  OBlGIIi   UJ= 

^-    nuo  nnd  phenacite, 
^agnesian  specie,  f"— iCf   ud^r^pe-S'  to- 
There  uamea,  belong  *^  ''^  ^J  /  rfes,  viUa.-site,  the 
trandite,  the  hydrous  '^^^^^^      ^      i,,,  wiUemite  and 
anhydrous  rincie  and  ^"f  ^X  the  third  Une  are  to  be 
tephroite,  with  roany  f"'^-'„^i^„  silicates  generaUy 
placed  the  various  hydrous  "^^'^ussed  f-.ther  on  m 
Lown  as  serpentine;   ^^^r^Z^         ies,  including  the 
Essay  Vin-  'h''  ^'"'T -nlUe  the  foliated  thermophyl- 
,  smatiechrysoUteandp^r  hte^th^t^^  eoUoid   species, 

lite  and  marraoUte,  and  the  ""^ '.  ^1,^  nameof  serpen- 
';i,;alite,  and  that  ^^  ^^^J^  i^lTphU,  P«sents  the 
tine.  The  anhydrous  SP^"^^'  '^  /^  3iiiea  as  the  seipen- 
tle  atomic  ratios  for  protoxydsand^^^^^^ 

tine  group,  for  ^''"«l>,f  "^'X  oJ  note  that,  as  Daubr^e 
nragnesian  speeds  " ''. '^"JXdrated  and  (used,  hreata 
has  shown,  serpentnie,  when    eny  ^„a  enstatite, 

np  into  a  mixture  of   "-^'^^i^^/iUs  intermediate  in  com- 
t^een  ^vWcl.  exclutog  wat^^^^^^^^  „Hte,  may  be 

position*    With  the  hydrous  U  ^^^  ^^^  ^^lon- 

■      the  niccolio  species,  genthite^  ^^^^.^^  ^j  ^i^jaeates, 

s  84.  We  come  next  to  tne  g  woUastomte,  en- 

.epresented  among  ^M-^^ "nd  the  manganesian    ■ 
statite,  pyroxene,  '^ny  amphAo  ^^^^^  sub-specres. 

,necie3  rhodonite,  with  i-^l*""'  "l  .„  UsiUcates,  picros- 
^^  these  are  the  y*^""'  "S^r  with  hydrorhodo- 
mine,  aphrodite,  and  "=«■»''*?' '"^These  various  bisilicates 

Te  'dioptase.  a-^  ^Xp    iolil'cl^oup  by  plombier  te 
are  represented  among  tepec^t^^^  ^^^^^  ^y  Dau- 

and  xonaltite;  the  «"»"  ^^^^^^  at  the  hot  spring  o£ 
b,fe   in   the  process  ««  £°™       a,,  o^ygen-ratio,  1.2.2. 
plorabiSi-es  in  France,  »*    "\  H        ^^y  „£  vemark  that, 
Ofthelesshydratax— .t^^^^^ 
♦  ComptesRendusdelAcaa-u 


T.l 


THE  CRENITIC   HYPOTHESIS. 


147 


as  observed  by  Rammelsberg,  it  occurs  in  concentric 
layers  with  the  anhydrous  species,  rhodonite  (bustamite), 
and  the  hydrous  quadrisilicate,  apophyllite. 

While  many  amphiboles  have  the  ratio  of  a  bisilicate, 
others  are  believed  to  have  a  ratio  (excluding  a  little 
water)  of  4:9,  not  far  from  that  of  pectolite,  with  which 
we  have  placed  them.  Here  also  comes  the  hydrous  mag- 
nesian  species,  spadaite.  Different  analyses  have  assigned 
to  talc  the  ratios  for  the  fixed  bases  of  2 : 5  and  1 :  3  (the 
water  being  variable),  —  the  latter  corresponding  to  sepio- 
lite,  1:3:1.  For  neither  of  these  do  we  know  any  cor- 
responding pectolitic  silicate. 

§  85.  We  come,  in  the  last  place,  to  the  quadrisilicates, 
which  have  no  known  representatives  among  hydrous 
magnesian  species,  or  among  anhydrous  silicates,  if  we 
except  the  titanosilicates,  titanite,  and  guarinite.  They 
are,  however,  represented  in  the  pectolitic  group  by  no 
less  than  three  species,  okenite,  apophyllite,  and  an  un* 
named  species  got  artificially  by  Daubr6e.  It  is  fibrous, 
like  okenite,  is  decomposed  by  acids,  and  is  a  hydrous  sili- 
cate of  lime,  with  six  per  cent  of  soda,  giving  the  ratios, 
1:4:^.  Pectolite,  it  will  be  recollected,  contains  in  like 
manner  about  nine  per  cent  of  soda,  while  apophyllite 
contains  five  per  cent  of  potash  and  a  little  fluorine. 

§  86.  The  process  by  which  this  unnamed  pectolitic 
silicate  was  obtained  by  Daubrde  is  very  instructive,  as 
showing,  in  many  ways,  the  action  of  heated  water  on  an 
undifferentiated  silicate  of  igneous  origin.  He  took  for 
the  subject  of  his  experiments  a  common  glass,  the  analy- 
sis of  which  gave  silica  68.4,  alumina  4.9,  lime  12.0,  mag- 
nesia 0.5,  and  soda  14.7  =  100.5.  Tubes  of  this  glass  were 
sealed  up,  with  many  precautions,  in  tubes  of  iron,  with 
about  one-third  their  weight  of  pure  water,  and  exposed 
during  several  weeks  to  a  temperature  not  less  than 
400°  C.  At  the  end  of  this  time  the  glass  was  found  to 
be  completely  disaggregated  and  changed  into  a  white 
fibrous  or  lamellar  substance,  composed  in  great  part  of 


il 


I 


n^GIK  OF  CET8TA1.UNE  MOM.  f». 

11«  THE  ORIGIN  Ui! 

f  lime  and  soda  in 
tte  fusible  reotoWc  <l"''f»|;;f;f  abundant  crystals  of    • 

,he  composition  ot  a      •  ->         '/.,j,re  also  included  mi- 
Z  cryslls  of  tWB  latV^ouu..  -1  were  ^^^^ 

ttc/l-ic  g^i-  °  ;  *t:..„er.    "he  iron  of  these  mm- 
nr  Tiicotite,  probably  tne  lo  ^^^^^ 

:  als  ^vas  perhaps  derived  fr-  the  v         ^^^.^_^  ^^  ,^      ^ 
S  87.  The  net  result  of  the  P     J       ^.^.^^^^  „p 

water  on  the  glass  ^™.s  *at  f  e  v  .^^  ^^^j^_  ^„4 

L  0  per  cent  of  its  siUca,  6*.«  P^°%it,i  the  remaining 
ttn  Tr  cent  of  its  alumina;  the  lime,  w         j^^^i^edths) 
mea'  and  soda  and  -^^"^  Z  ^pa-'ed  silica 
0  ming  the  pectolitic  sUiea  e     U      ^^  ^^^^  „j.,t,Uaed 
fhe  larger  part  separated  in  the  r  ^^^^  ^^^,^,3 

corresponding  to  an  "^yS^^/,^  ,„,i  rfs,  85.0  per  cent  of 
But  as,  according  to  D»ubr6e  s     j        ^^^  ^^^^^  „^e 

the  alumina  had  P»f  ^^f  °  Jthan  9.7  parts  of  alum>n«- 
for  63  parts  of  soda  n°' '"'^^i<,„.ai„minate  in  solution  a 
which  should  give  for  the  sUieo  ^^  ^^^^^         ji- 

■  cance  wmcn 

n'stW^iasrecora^expen^^^^^^ 

above  made  to  'i«te™"'%f'  'tl  such  as  obsidian  and 
wTtcr  upon  vitreous  volcanic  r»*8,  b  ^^^„g,„  ,„- 

Lute,  which  gave  similar  res^^s        g^  ^j  ^^. 

cording  to  him,  not  so  we^  detoe  ^^  ,, 

din,  of  oligoclase,  of  P^t^^'-^t^t  change,  though  m- 
the'se  tubes  suffered  J  "W-en^^^ed  from  the  glass, 
crusted  with  crystals  ot  quari 


v.] 


THE  CRENITIC  HYPOTHESIS. 


149 


This  stability  was  to  have  been  expected  from  the  fact 
that  crystals  of  pyroxene  are  formed  under  similar  con- 
ditions, and,  as  we  shall  see,  both  albite  and  orthoclase 
have  since  been  crystallized  at  high  temperatures  in  pres- 
ence of  solutions  of  alkaline  silicates.  Another  experi- 
ment, mentioned  by  Daubrde  in  this  connection,  is 
important.  By  heating  in  a  glass  tube  with  water  a 
refractory  clay  (probably  under  similar  conditions  to  the 
preceding  exi)eriments),  this  became  filled  with  white 
pearly  hexagonal  scales,  resembling  a  mica.  They  were 
fusible,  attacked  by  hydrochloric  acid,  and  contained  both 
silica  and  alumina,  being  seemingly  a  product  of  the  ac- 
tion of  the  alkaline  silicate  from  the  glass  upon  the  infus- 
ible kaolin.* 

Daubrije  recalls  in  this  connection  the  observations 
of  Fr<imy,  who  found  that  colloidal  silicates  of  soda 
(water-glass),  made  at  low  temperatures,  and  containing 
a  large  excess  of  silica,  give  up,  when  heated,  a  portion 
of  their  silica,  which  separates  in  a  form  having  the  insol- 
ubility of  quartz.f  Daubrde  well  remarks  that  we  appear 
to  have,  in  his  own  experiments  at  high  temperatures  with 
water,  a  similar  breaking-up  of  the  silicate  of  soda,  which 
had  separated  from  the  glass,  into  quartz  and  a  more  basic 
silicate. 

§  89.  In  connection  with  this  apparent  solubility  of 
alumina,  under  certain  conditions,  in  watery  solutions  of 
alkaline  silicates,  the  observations  of  Ordway  are  very 
important.  In  his  extended  studies  of  the  alkaline 
silicates  in  1861,  he  notes  that  Bolley  had  shown  that 
magnesia  and  lime  are  slightly  soluble  in  solutions  of 
water-glass,  and  that  Kuhlmann  had  obtained  a  double 
silicate  of  potash-  and  manganese  as  a  violet-colored 
vitreous  mass,  giving  a  brown  solution  with  water,  and 
had  also  observed  a  similar  combination  of  cobalt.      Ord- 

« 

*  Daubr^e,  G^ologie  Exp^rimentale,  pp.  159-179. 
t  Fremy,  Comptes  Bendus  de  1' Academic  des  Sciences  (1856),  xliii., 
p.  1146. 


■>%- 


i'-\  ) 


It    . 


IV. 


"ISO  TUcJ  vi**""' 

rfnot  taken,  a  i.ovUoa  of  -"J^on  by  peroxyaato. 
which  is  not  scpavatea  t'o™  t  le  ^^^^^^^  ^^^^^  of 

Zl  but  -n-eviectly  ^  »^1>"^^^^  ^^.j^,i„„,  but  the  liquA 
the  water-glass  is  ^  '"  "7„„,^.%iear  again  on  concentia- 

^-  '■t:ts::w\i"- :  fe.{  a.p»  ^^ -^ 

:Xuon":f  a  metallic  ^"J^Z  I  -dissolved 
wa  evglass,  the  P™7'"^,tJe  thus  takes  up  no  incon- 
;  .giition.      "  A  bcimd  ^'>;'=;f  J\,„„,  ,i„c,  manganese, 
denvble  amount  of  *!>«  °^y^^J„„,y."      By  agitatmg  a 
tin,  antimony,  copper,  a^>d  mere    y       ^^^^^.gi,^,  ^^  a 
,tiou  ot  ferrous  sulphate  wi»  °       .        .  which,  after 
;tser;rrtly  fined  with  «^-;^XV  This  solubility  of 
Xtion,  has  a  very  deepj-l-jl  of  alkaline  siUcates 
f..ilip  oxvds  m  aqueous  »u  obscure  tactb 

:« Va  rational  e.;— »  "^  J^  ..^  presence 
to  mineralogical  '='^^™'''y> ''^Lev-oxyds,  and  of  metalhc 

b Je  and  others  on  the  e""*'^^       „i„eral  species,  by 
e    stalline  zeolites,  -"'^  J^^^liwaters  on  the  bricks 
Z  slow  action  of  «™»^  *rmasonry  in  France  and    , 
and  mortar  of  ancient  Koma  ^^         ^^at  his 

Atoria.     It  was  at  ^ '""^''^'Xhot  water,  here  rising 
tst  of^evvations  were  made      Th        ^^^^^^^^  ^  j^^,^ 

f  om  a  fissure  in  a  8'™*°  J" "fe  superficial  waters,  the 
'gCel,  and  to  protect  i     rom  tl.J^  P  ^  ,,      e^e 

lomans  had  capped  the  splig.^^   ^^^  P'"**^   "C er  a 
•-n  Cm  bCa^h^hl  concrete,  exten  mg  -- 
rghof-rethanahundredmeu^^.-/^     I^^ 
Ses  in  thickness>e  wf  -  w  ^_^^_    The  w.ter,  hav- 
through  vertical  ctann^^^^^^^^^^^^^,_^^,,  33,  . 


v.] 


THE  CRENITIC   HYPOTHESIS. 


151 


ing  at  its  outlet  a  temperature  of  70°  C,  fills  the  gravel 
beneath  the  roof  of  concrete,  and  a  portion  filters  slowly 
upward  through  this.  The  concre^  itself  was  made  of 
fragments  of  burnt  red  brick,  with  others  of  sandstone 
and  of  a  friable  granite,  the  whole  in  a  calcareous  cement. 
Repairs  having  required  cuttings  to  be  made  in  this  mass, 
it  was  found  to  contain  numerous  crystallized  mineral 
species,  foi-med  through  the  action  of  the  water,  which 
were  examined  by  Daubr(3e,  with  the  aid  of  De  Senarmont 
for  the  crystallographic  determinations,  and  first  described 
in  1858. 

§  91.  The  substance  of  the  fragments  of  brick  was 
found  to  be  altered  to  some  depth,  while  the  numerous 
cavities  therein  were  lined  or  filled  with  various  matters, 
often  distinctly  crystallized.  Among  these  were  identi- 
fied chabazite  and  phillipsite  (christianite),  gismondite, 
implanted  on  the  chabazite,  scolecite,  and  what  is  desig- 
nated by  Daubrde  as  mesotype  (thomsonite  or  natrolite). 
In  the  calcareous  cement  were  well  defined  crystals  of 
apophyllite,  containing,  as  usual,  a  little  fluorine ;  while 
in  cavities  in  the  lower  part  of  the  concrete,  near  the 
gravel,  was  found  an  abundant  gelatinous  matter,  which 
was  detected  in  the  act  of  deposition  in  recent  cuttings 
in  the  mass  through  which  the  water  was  still  oozing. 
This  matter  elsewhere  had  consolidated  into  a  white 
mammillary  concretionary  fibrous  substance,  which  was 
found  to  be  a  hydrous  silicate  of  lime,  with  but  1.3  hun- 
dredths of  alumina,  and  constitutes  the  pectolitic  species, 
plombierite,  already  noticed  (§  84).  With  the  various 
minerals  in  the  concrete  were  also  found  an  abundant 
deposit  of  silica  in  the  form  of  hyalite,  and,  more  rarely, 
crystals  of  tridymite,  and  globules  of  chalcedony,  together 
with  calcite  in  well  defined  crystals,  arragonite,  and  fluo- 
rite.  The  chabazite  was  often  found  adherent  to  frag- 
ments of  wood  enclosed  in  the  concrete,  recalling,  as 
observed  by  Daubrde,  the  similar  occurrence  of  zeolites 
with  fossil  wood  in  lacustrine  limestone   in   Auvergne. 


162 


THE  OUIOIN   OF  CUY8TALLINE  ROCKS. 


:ir^i; 


The  variouM  minerals  named  were  absent  from  the  frag- 
ments of  friable  jj;ranite,  while  in  the  underlying  gravels 
the  only  matter  deposited  was  an  amorphous  aluminous 
silicate,  compared  to  halloysite,  and  found  also  in  the  con- 
crete. 

§  92.  The  fragments  of  red  burnt  brick  in  the  cement 
had  undergone  an  alteration  from  their  surface,  marked 
by  concentric  lines  of  changed  color,  as  well  as  by  the 
development  of  zeolites,  and  also  of  an  amorphous  nuvtter 
compared  by  Daubrdo  to  palagonite.  In  these  fragments, 
the  amount  of  combined  water  had  increased  from  two  or 
three  hundredths  in  the  centre,  to  eight  hundredths  in 
the  outer  inliltrated  portion,  in  which  the  amount  of 
matter  soluble  in  nitric  acid  was  equal  to  fourteen  or  fif- 
teen hundredths,  including  a  notable  proportion  of  potash, 
supposed  by  Daubrile  to  have  been  taken  up  from  the 
waters.  The  silica,  alumina,  and  lime  of  the  new  mineral 
species  were  derived  from  the  cement  and  the  biicks,  the 
calcination  of  which  had  probably  rendered  them  more 
susceptible  to  chemical  cliange.  As  has  been  pointed  out 
by  Duubrde,  the  resemblance  between  these  species  and 
the  similar  ones  found  in  many  rocks  extends  even  to 
minor  details  of  crystalline  form  and  association.  The 
small  geodes  linad  with  crystals,  in  the  bricks,  as  the 
writer  can  testify,  cannot  be  distinguished  by  inspection 
from  many  similar  cavities  in  certain  amygdaloids. 

§  93.  Similar  phenomena  have  since  been  noticed  in 
the  ancient  constructions  around  the  thermal  waters  of 
Luxeil,  Bourbonne,  and  otliers  in  France,  and  at  Oran  in 
Algeria.  These  localities  have  added  little  more  to  our 
knowledge  of  the  production  of  silicates,  though  at  some 
of  them,  and  notably  at  Bourbonne,  besides  zeolites,  have 
been  found  various  crystalline  metallic  sulphides  derived 
from  the  transformation  of  metallic  objects  enclosed  in 
the  concrete.  The  water  of  the  last  named  locality, 
which,  unlike  that  of  Plombidres,  rises  from  the  muschel- 
kalk,  has  a  temperature  of  about  60°  C,  and  is  a  neutral 


,/ 


f 


el- 
lal 


V.J 


THE  CUKNITIC   HYPOTHESIS. 


168 


saline  contiiining  seven  or  eight  thousantltlis  of  mineral 
mutterH,  cliielly  8ulphates  and  cliloricls  of  alkalies,  and 
of  linie  and  magnesia;  while  that  of  PlombiOres  contains 
only  about  tlireo  ten-thousandths,  and  is  also  said  to  be 
neutral.  As  renuirked  by  Daubr<;e,  it  is  probable  that 
the  a'jtion  of  the  water  in  the  formation  of  these  mineral 
silicates  is,  to  a  great  extci't,  independent  of  its  composi- 
tion, since  pure  water,  in  aciing  upon  finely  divided  alka- 
liferous  materials,  soon  becomes  itself  alkaline. 

As  regards  other  silicated  deposits  from  thermal  waters, 
we  may  notice  the  case  of  the  L-.ths  of  St.  Honord 
(Nievre),  the  waters  of  which,  having  a  temperature  of 
81°  C,  yield  a  finely  laminated  white  translucent  sub- 
stance in  concentric  layers,  which  appears  from  analysis 
to  be  a  hydrous  silicate  of  alumina,  with  a  large  excess  of 
silica,  but  is  probably  a  mixture.  Mention  is  also  made 
of  a  similar  deposit  from  a  mineral  spring  at  Cauterets, 
which  is  talcose  in  aspect,  and,  according  to  qualitative 
analysis,  is  a  silicate  of  alumina,  with  magnesia  and  alka- 
lies.* In  this  connection  mention  should  be  made  of  the 
occurrence  at  the  thermal  spring  of  Olette  (Pyrenndes 
Orientales)  of  a  crystalline  silicate,  having,  according  to 
Descloizeaux,  the  crystalline  form  of  stilbite,  of  which  it 
has  also  the  composition.! 

§  94.  As  an  example  of  a  zeolite  apparently  in  process 
of  formation,  may  be  mentioned  the  observations  of 
R.  Hermann,  who  found  in  the  crevices  of  a  columnar 
basalt  at  Stolpenau,  in  Saxony,  an  amorphous  white  plas- 
tic substance,  which  after  some  time  changed  into  acicular 
crystals  of  scolecite.J  More  recently,  Renevier  has  de- 
scribed the  occurrence  of  a  white  subtranslucent  matter, 
unctuous  to  the  tou  h,  gelatinous  at  first,  but  becoming  a 

*  For  a  summary  of  the  observations  of  Daubrde,  the  details  of  which 
are  found  in  several  papers,  see  his  G^ologie  Experimentale,  1879,  pp. 
179-207. 

t  Cited  by  Dana,  System  of  Mineralogy,  5th  ed.,  p.  443. 

t  Jour,  f  iir  Prakt.  Chemle,  Ixxii.  Cited  by  Dana,  System  of  Mineral- 
ogy, su6  roce  Scolecite.  •    ■ 


*. 


■ 


n 


I 


m 


M 

1" 

1  if 

1     , 

'lis'''' 

■f '£»-,,  I 

II' 

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154 


THE  ORIGIN   OF  CRYSTALLINE  ROCKS. 


[V. 


plastic  mass,  and  called  by  the  quarrymen  "  mineral  lard," 
found  in  constructing  a  tunnel  in  the  molasse  or  tertiary 
sandstone  near  Lausanne,  in  Switzerland,  in  1876.  This 
substance,  which  formed  layers  of  from  one  to  three  centi- 
metres on  tlie  walls  of  fissures,  was  said  by  observers  to 
have,  in  some  cases,  taken  on  a  crystalline  form,  a  fact, 
however,  which  Renevier  was  not  able  to  verify.  When 
dried  at  100°  C,  it  was  found  to  be  a  hydrated  double 
aluminous  silicate,  giving;  the  oxygen-ratios  of  chabazite, 
1:3:8:6;  the  bases  being  lime  and  potash,  with  3.14 
per  cent  of  magnesia.* 

§  95.  A  remarkable  fact  in  the  history  of  zeolites  is- 
that  lately  made  known  b}^  the  researches  of  Murray  and 
R^nard,  that  a  decomposition  of  volcanic  detrital  material 
goes  on  at  low  temperatures  in  the  depths  of  the  ocean, 
transforming  basic  silicates,  "represented  by  volcanic 
glasses  such  as  hyalomelane  and  tachylite,"  into  a  crystal- 
line zeolite  on  the  one  hand,  and  the  characteristic  red 
clay  of  deep-sea  deposits  on  the  other.  To  quote  the  lan- 
guage of  the  authors,  this  process,  "  in  spite  of  the  temper- 
ature approximating  to  0°  C,  gives  rise,  as  an  ultimate 
product,  to  clearly  crystallized  minerals,  wliich  may  be 
considered  the  most  remarkable  products  of  i  iie  chemical 
action  of  the  sea  upon  the  volcanic  matters  undergoing 
decomposition.  These  microscopic  crystals  are  zeolites, 
lying  free  in  the  deposit,  and  are  met  with  in  greatest 
abundance  in  the  typical  red-clay  areas  of  the  central 
Pacific.  They  are  simple,  twinned,  or  spheroidal  groups, 
which  scarcely  exceed  half  a  millimetre  in  diameter.  The 
crystallographic  and  chemical  study  of  them  shows  that 
they  must  be  referred  to  christianite,"t  which  is  but  an- 
other name  for  phillipsite.  We  have  here,  as  in  the  case  of 
palagonite,  and  in  ordinary  zeolitic  rocks,  the  breaking-up 
of  a  basic  igneous  silicate  into  an  acidic  crystalline  alumi- 
nous silicate  of  lime  and  alkalies,  and  a  more  basic  insolu- 


*  Bull,  de  la  Soc.  Vaudoise  des  Sci.  Naturelles,  x 
t  Lecture,  in  Nature,  June  5,  1884,  p.  133. 


disl 

.  tioj 
eqi 
will 
pr< 
drii 

mil 

ha^ 

beij 

digl 


±0. 


v.] 


THE  CRENITIC  HYPOTHESIS. 


166 


ble  residue,  rich  in  iron-oxyd ;  a  portion  of  which,  as  is 
well  known,  separates  from  these  red  clays  in  the  form  of 
concretions,  often  with  oxyd  of  manganese. 

§  96.  We  have  next  to  examine  the  conditions  under 
which  zeolites,  fekbpars,  and  related  silicates  have  been 
artificially  produced  in  the  chemist's  laboratory.  When, 
according  to  Berzelius,  three  parts  of  silica  and  two  of 
alumina  are  fused  with  fifteen  parts  or  more  of  potassic 
carbonate,  and  the  cooled  and  pulverized  mass  is  exhausted 
with  water,  there  remains  a  double  silicate,  which  has  the 
composition  of  a  potash-anorthite,  with  the  ratios,  1:3:4, 
corresponding  to  potash  28.68,  alumina  32.04,  and  silica 
39.31 ;  the  excess  of  silica  being  dissolved  as  an  alkaline 
silicate.*  The  analogous  soda-compound  may  be  pro- 
duced in  like  manner.  A  similar  silicate,  according  to 
Ammon,  is  obtained  when  recently  precipitated  alumina 
is  added  to  a  moderately  concentrated  and  boiling  solution 
of  caustic  soda,  mixed  with  silicate  of  soda.  The  alumina 
is  at  first  completely  dissolved,  but  a  white  pulverulent 
precipitate  soon  separates,  which  is  a  hydrous  silicate  of 
soda  and  alumina,  having  for  the  fixed  bases  the  same 
ratio  as  before,  1:3:4;  corresponding  to  anorthite  and 
to  thomsonite.  f 

§  97.  C.  J.  Way,  in  his  studies  on  the  absorption  of 
bases  by  soils,  prepared  artificial  aluminous  silicates  by 
dissolving  alumina  in  soda-lye,  and  adding  thereto  a  solu- 
tion of  silicate  of  soda  containing  not  more  than  one 
equivalent  of  silica  to  one  of  alkali  (R  :  Si=l  :  3),  to 
which  any  convenient  excess  of  soda  might  be  added.  A 
precipitate  was  thus  obtained,  which,  when  washed  and 
dried  at  100°  C,  was  a  white  pulverulent  silicate  of  alu- 
mina and  soda,  holding  twelve  hundredths  of  water,  and 
having  almost  exactly  the  oxygen-ratios,  1:3:6:2; 
being  a  true  soda-mesolite.  This  artificial  silicate,  when 
digested  with  lime-water,  or  with  any  neutral  salt  of  lime, 

*  Cited  In  Gmelin's  Handbook,  iil.,  431. 
t  Jaliresbericht  der  Chemie,  1862,  p.  128. 


'i!      IE 


tm' 


II 


156 


THE  ORIGIN  OP  CRYSTALLINE  ROCKS. 


-B(t 


I 


exchanged  its  soda  for  lime.  It  was  difficult  thus  to  sepa- 
rate the  whole  of  the  soda,  but  in  some  cases  the  replace- 
ment was  almost  complete,  and  a  scolecite  was  formed. 
Either  of  these  compounds,  when  digested  witli  sulphate 
or  nitrate  of  potassium,  was  converted  into  a  potash-meso- 
lite.  With  a  solution  of  a  magnesian  salt,  these  com- 
pounds gave  a  magnesian  double  silicate,  which  was  not 
particularly  examined.*  Berzelius,  by  adding  a  solution 
of  silica  to  one  of  alumina  in  potash,  in  proportions  which 
are  not  indicated,  found  the  mixture  to  solidify  in  a  few 
minutes  to  an  opaque  jelly  in  consequent  e  of  the  separa- 
tion of  a  silicate  of  alumina  and  potash  having  tl"  oxygen- 
ratios,  1:3:8,  which  are  those  of  analcito.t  Farther 
investigations  are  required  to  make  Icnown  the  precisu 
conditions  for  the  production  of  these  different  silicates, 
which  give  for  their  fixed  ele^ients  the  ratios  respc'ctively 
of  thomsonite,  meholite,  and  aiialcite.  The  most  basic  of 
these,  according  to  Berzelius,  is  formed  in  the  presence  of 
an  excess  of  a  soda-silicate. 

§  98.  Henri  Ste.-Claire  Deville,  by  mingling  solutions 
of  silicate  of  potash  and  aluniinate  of  soda  in  such  propor- 
tions as  gave  for  the  oxygen-ratios,  al :  Si=  3  :  G,  obtained 
a  gelatinous  precipitate,  Avliich  in  sealed  tubes,  at  temper- 
atures of  from  150°  to  200°  C,  was  gradually  changed  into 
hexagonal  plates  of  a  potash-soda  zeolite  with  the  oxygen- 
ratios,  1:3:6:2,  having  the  physical  characters  of  levy- 
nite.  The  residual  liquid  was  nearly  free  from  both  silica 
and  alumina.  On  repeating  this  experiment  at  a  higher 
temper  iture,  a  very  diffe^'ent  result  was  obtained.  There 
was  an  abundant  separation  of  silica  in  crystalline  grains, 
with  a  little  levynite,  while  an  alkaline  aluniinate  remained 
in  solution.  This  remarkable  dissociation  of  the  first- 
formed  aluminous  silicate  into  free  silica  and  soluble 
alumina  recallti  the  conditions  of  the  separation  of  quartz, 

*  Way,  On  th  i  Power  of  Soils  to  absorb  Manures,  Trans.  Royal  Soc. 
Agriculture,  1852,  xili.,  12.3-143. 

t  Cited  in  Gmeliu's  Handbook,  Hi.,  439. 


by  J 

not 
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the  e^ 
ing  ir 
soda 
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precedil 
des  JVIijT 

t  cJ 


n 


THE  CRENITIC   HYPOTHESIS. 


157 


already  noticed  in  §  87.  The  crystalline  silica  produced 
in  this  reaction  may  be  either  quartz  or  tridymite,  which 
latter  form  of  silica,  mingled  with  quartz,  was  obtained  in 
1879  by  Friedel  and  Sarrasin  by  heating  gelatinous  silica 
with  an  alkaline  solution  to  about  400°  C.  The  dissocia* 
tion  of  alumina  from  silica,  observed  in  this  experiment, 
serves  to  throw  light  on  tlie  origin  of  corunaum  and  spinel. 
In  other  experiments  with  mixtures  of  solutions  of  silicate 
and  aluminate  of  potash  in  sealed  tubes  at  200°  C,  Deville 
got  a  crystalline  compound  with  the  formula  of  phillipsite, 
1:3:8:5.  Subsequently,  De  Schulten,  in  similar  experi- 
ments, at  180°  C,  with  silicate  and  aluminate  of  soda, 
obtained  crystals  of  analcite,  with  the  ratios,  1:3:8:2.* 
§  99.  More  recent  investigations  in  the  same  direction 
by  Friedel  and  Sarrasin  are  very  instructive,  as  showing 
not  only  the  generation  of  feldspars  in  the  wet  way,  but 
the  production  at  will,  under  similar  conditions,  of  a  feld- 
si^ar  or  a  zeolite.  These  chemists  had  already,  by  heating 
a  mixture  of  silicate  v  'I  alumina  (precipitated  from  a  solu- 
tion of  chloride  of  aluminium  by  silicate  of  potasli)  with 
an  excess  of  a  solution  of  silicate  of  potash,  obtained 
crystals  of  orthoclase,  mingled  with  crystals  'o£  quartz  or. 
at  a  more  elevated  temperature,  of  tridymite.  In  subse- 
quent experiments,  undertaken  for  the  production  of 
albite,  a  similar  hydrous  silicate  of  alumina  was  mingled 
with  a  solution  of  silicate  of  soda  (the  silica  and  alumina 
in  the  proportions  of  the  soda-feldspar),  and  heated  to 
from  400°  to  500°  C.  Instead  of  the  anhydrous  albite, 
however,  were  obtained  crystals  of  analcite,  1:3:8:2; 
the  excess  of  silica,  with  soda  and  some  alumina,  remain- 
ing in  solution.  When,  however,  an  excess  of  silicate  of 
soda  was  employed,  the  whole  of  the  silicate  of  alumina 
was  transformed   into  albite.  f     Thus  analcite,  which  is 

*  The  results  of  Deville,  Friedel  and  Sarrasin,  and  De  Schulten  in  the 
preceding  paragraphs  are  cited  from  Michel  Levy  and  Fou'iu^,  Synthase 
des  Mine'raux  et  des  Roches,  Paris,  1882,  pp.  87-134  and  161-164. 

t  Compte  Rendu  de  I'Acad.  des  Sciences,  le  30  Juillet,  1883. 


168 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


[V. 


'■"111  H.S" 


ii  '': 


formed  by  the  action  of  thermal  springs  below  70°  C,  is 
equally  produced  at  180°  C,  as  in  the  experiments  of  De 
Schulten,  and  at  400°  C.  and  upwards. 

§  100.  We  h.^ve  th\i8  far  considered  among  aluminous 
double  silicates  those  which  present  the  oxygen-ratio  of 
R  :  al  =  1  :  3,  and  have  only  mentioned  incidentally  the 
epidote  and  meionite  groups.  The  numerous  experiments 
already  detailed  suffice  to  show  that  the  double  silicates 
of  alumina  and  alkalies,  formed  under  very  varied  condi- 
tions in  the  wet  way,  in  the  presence  of  an  excess  of  alkali, 
always  present  this  ratio,  of  1  :  3.  When,  however,  we 
pass  to  aluminous  double  silicates  with  other  protoxyd- 
bases,  we  find  many  with  the  ratio,  1  :  2,  as  in  the  epidote 
and  meionite  groups  ;  with  1  :  1,  as  in  the  alumina-garnets, 
gehlenite,  and  biotite  ;  or  even  2  :  1,  as  in  melilite,  phlogo- 
pite,  and  many  hydrated  alumino-magnesian  species  of  the 
chlorite  group.  The  genesis  of  these  various  calcareous 
and  magnesian  alumina-silicates,  so  conspicuous  in  the 
rocks,  is  an  important  and  unsolved  problem. 

Artificial  zeolitic  compounds,  like  the  soda-mesolite 
formed  by  Way,  with  the  ratio,  R  :  al  =  1  :  3,  may,  as  we 
have  seen,  exchange  their  alkaline  'oase  for  lime  or  mag- 
nesia, but  for  the  silicates  in  cjuesticii,  v...  »•.  ii'.oh  this  ratio 
is  1  :  2,  or  1:1,  or  2  :  1,  the  coi-respLndiii':-  silicates  of 
alumina  ani  alkalies  are  as  yet  unknown  to  chemistry, 
being  soluble,  and  probably  unstable  and  uncrystallizable. 
Analogy,  however,  as  well  as  the  modes  of  occurrence  of 
these  calcareous  and  magnesian  silicates,  would  lead  us  to 
expect  the  production  of  such  alkaline  double  silicates, 
under  certain  conditions,  in  solution,  and  we  are  not 
without  evidence  of  the  occurrence  of  such  compounds. 
The  soluble  alkaline  extract  from  the  decomposition  of  an 
al  \imipous  glass,  in  Daubr(!e's  experiment  (§  87),  holding 
in  solution  I  oth  silica  and  alumina,  g|ive,  if  the  data  are 
eycyo.t  the  oxygen-ratio  for  R  :  al  :  Si  =  3  :  1  :  4.  We 
lavt)  also,  in  Friedel  an-  Sarrasin's  experiment  (§  99), 
t  iv  gep  iri,tion  <:  f  anaicite  from  a  like  solution,  which  re- 


§ 


* 
t 


v.] 


THE  CRENITIC  HYPOTHESIS. 


169 


tained  both  silica  and  alumina  in  solution.  Researches  in 
this  direction  will  probably  make  known  to  us  the  condi- 
tions under  which  such  residual  solutions  may  be  pro- 
duced, containing  alkalino-aluminous  silicates  with  the 
ratios  corresponding  to  epidote,  garnet,  biotite,  phlogopite, 
and  the  chlorites. 

§  101.  Magnesian  silicates  corresponding  to  the  zeolitic 
and  feldspar  group  are  rare,  and  known  to  us  only  through 
the  artificial  compound  of  Way,  the  species  iolite,  esmar- 
kite,  and  fahlunite,  and  certain  partially  magnesian  zeo" 
lites.  Chabiizite,  when  finely  pulverized,  according  to 
Eichliorn,  exchanges  a  portion  of  its  lime  for  potash  when 
digested  with  a  potassium  salt,  but  is  very  slightly  at- 
tacked by  a  solution  of  magnesian  chlorid.*  The  more 
silicic  of  these  zeolites  are  apparently  indifferent  to  such 
substitutions  and,  as  we  have  seen,  phillipsite  is  formed 
in  sea-water.  We  should,  however,  expect  the  more  basic 
of  the  calcareo-aluminous  silicates,  Avith  the  ratios,  R  :  al 
=  1  :  1  or  2  :  1,  to  be  very  susceptible  to  replacement  by 
magnesia.  Bunsen  has  shown  that  palagonite,  a  hydrous 
silicate  of  this  class  (§  67,  footnote),  with  a  large  propor- 
tion of  calcareous  base,  decomposes  even  a  solution  of 
ferrous  sulphate,  which  removes  its  lime,  and  it  would 
doubtless  decompose  in  a  like  manner  magnesian  salts.  I 
have  long  since  shown  that  an  artificial  hydrous  silicate 
of  lime  readily  decomposes  a  solution  of  magnesium- 
chlorid,  with  the  production  of  calcium-chlorid  and  a 
magnesian  silicate ;  a  result  in  accordance  Avith  the  earlier 
observations  of  Bischof  on  the  power  of  solutions  of  sili- 
cate of  lime  to  decompose  magnesian  salts,  f 

§  102.  While  on  one  side  of  what  we  may  call  the 
normal  type  of  alumina-protoxyd  silicates,  with  the  ratio, 
R  :  al  =  1  :  3,  as  seen  in  the  group  of  the  feldspars  and 
the  zeolites,  we  have  those  with  an  excess  of  protoxyds 
(including  scapolites,  epidote,  garnet,  idocrase,  melilite, 

*  Cited  by  S.  W.  Johnson,  Amer.  Jour.  Sci.,  1859,  xxviii.,  14. 
t  Hunt,  Chem.  and  Cicol.  Essays,  p.  122. 


i 


I 


i  *i 


"'^^V'.u' 


m 


160 


THE  ORIGIX  OF  CRYSTALLINE  ROCKS. 


[V. 


I 


I-: 


1^ 


.J 


gehlenite,  biotite,  phlogopite,  and  the  chlorites),  there  is 
another  series  of  aluminous  silicates  in  which  the  propor- 
tion of  protoxyds  falls  below  this  normal  ratio,  and  still 
another  series  in  which  protoxyd-bases  are  absent.  Of  the 
latter  we  need  only  name  the  anhydrous  species,  andalusite, 
fibrolite,  and  cyanite,  and  the  hydrous  species,  pyrophyl- 
lite,  pholerite,  and  kaoliiiite,  with  the  amorphous  halloy- 
site,  a  more  highly  hydrated  and  colloidal  form  of  the 
kaolin-silicate,  and  others.  The  aluminous  protoxyd-sili- 
cates  with  a  diminished  proportion  of  alkali,  constitute  an 
important  group,  including  most  of  the  tourmalines  and 
the  pj'incipal  non-maguesian  micas,  muscovite,  margaro- 
dite,  euphyllite,  damourite  or  sericite,  and  paragonite,  but 
excluding  the  rarer  lepidolito  of  veinstones,  which  is  more 
highly  alkaliferous.  In  the  following  list,  the  formulas 
for  the  last  four  species  named  have  been  taken  from 
Dana's  "Systcn  of  Mineralogy,"  while  the  three  given 
for  different  varieties  of  muscovite  have  ijcen  devised  so  ■ 
as  to  facilitate  comparison  with  the  latter,  and  at  the 
same  time  to  represent,  as  near  as  may  be,  the  variable 
composition  of  the  anhydrous  mica. 

NON-MAG]SrEST.\N  OR  MUSCOVITIC  MICAS. 


Muscovite  (a, 
Muscovite  (b) 
>fiisco.tke  (c^ 
Miin.-arodite . 

Damoo-ito  . 
ParagonUs;    ., 


R    :   r    :    Si  :   11 


9 
9 
9 
9 
9 
12 
12 


§  lOS,  The  free  oient  occurrence  of  muscovite  in  endo- 
genou;-.  granitic  veins  with  orthoclase  and  albite,  shows 
that  Lhis  species,  like  the  feldspars,  may  be  crystallized 
from  solutions.    At  the  same  time,  their  composition  and 


groud 
like  tjf 
theles 


T.J 


THE  CRENTTIO   HYPOTHESIS. 


161 


their  geological  relations  suggest  thot  this  and  the  related 
micas  have  more  generally  beea  cleri  >'ed,  directly  or  indi- 
rectly, from  the  sub-aerial  decay  of  the  feldspar  of  granitic 
rocks.  While  these  micas  are  rare,  or  altogether  absent 
from  the  oldest  granitoid  gneisses,  they  become  compara- 
tively abundant  in  the  younger  gneisses  and  their  asso- 
ciated mica-schists,  and,  finally,  in  the  forms  of  damourite, 
sericite,  and  paragonite-schists,  characterize  great  masses 
of  strata  among  the  still  younger  Transition  strata.  We 
have  called  attention  to  the  fact  that  decayed  feldspars, 
already  changed  to  the  form  of  clay,  and  approaching  to 
the  kaolin-ratio,  in  which  al  :  Si  =  3  :  4,  still  retain,  in 
many  cases,  a  few  hundredths  of  alkali  (§  63)  ;  while  the 
three  anhydrous  silicates  of  alumina,  —  andalusite,  fibro- 
lite,  and  cyanite,  —  which  are  frequently  found  crystallized 
in  certain  mica-schists,  have  each  the  ratio,  3:2.  It  will 
be  readily  seen  that  the  separation  of  these  highly  alumi- 
nous silicates  from  clays  still  holding  a  little  alkali  would 
leave  residues  having  essentially  the  composition  of  the 
micas  given  in  the  above  table.  There  are,  however, 
other  mica-schists  which  are  not  accompanied  by  such 
anhydrous  aluminous  silicates,  but  on  the  contrary  are 
associated  with  serpentines  and  chloritic  minerals,  indica- 
ting in  the  waters  of  the  time  a  very  different  condition 
from  that  which  we  have  first  supposed,  and  pointing  to 
the  intervention  of  soluble  silicates.  That  these,  b}'  their 
union  with  the  kaolin  from  decayed  feldspars,  might  yield 
muscovitic  micas,  will  be  evident,  when  we  note  that  the 
elements  of  one  equivalent  of  kaolinite  united  with  one 
of  thomsonite,  or  of  natrolite,  would  give  essentially  the 
oxygen-ratio  of  muscovite  or  margarodite,  and  two  of 
kaolinite  with  one  of  thomsonite  that  of  damourite  or 
paragonite.  * 

§  103  A.  [The  tourmalines  constitute  an  important 
group  of  double  aluminous  silicates,  which,  though  very  un- 
like the  muscovitic  micas  in  physical  characters,  are  never- 
theless, as  long  since  pointed  out  by  Rammelsberg,  closely 


1^ 


i^ 


'""..ii 


.  nriGiK  or  cbystALLOT  bocks.  tV. 

•ifto  THE  oraciJ*  ^^  _ 

•^^  .  •  A  nresent  sinii- 

.eUtea  to  «,e™  in  e— ^  »»po^^^^^^^^^^^^^  Ld  the  pro 
1-  va.^ing  veUt,7  «  ^^„,^  „,  ^.e  to— ^e/s 
tnxvd-bases.     int  e^  analyses  ot  spti.ii" 

tS  chemtat  in  1850,  based  on  the  a  J       ^  ,,tirfactory 
So^  thirty  localities,  gave  nm  he  d     ^,^^^^  ^^,  ^^^^ 
dassu.eatio„  of  «--»-        /ly  be  added  as  a  s.xtt. 
tho  red  tourmaline  of  ^°^"      ^  ^„„,,„,  a  considerable 
In  ot  these  cont^n    as  is  ^v  1  ded 

though  varying  ™'°™*  °*  ^  portion  oi  silica.  These 
by  lUininelsberg  »' "^P^^'^  ^.^a'^aliUe  by  the  nature  oi 
/ve  divisions  are  d'^tu  guisl^  ^^^^^^^  ^^^^^.^  ^  ,  „£ 
their  inotoxyd-bases,  ana  uy  ^^^^^^  yellow,  or 

pvotoxyd,  ses<i«ioxyd,  '»''\  ^f  ^y.i  ,ve  have  designated 
Cown  nvagiiesian  toummUne,  wh>  ^^  ^^^  ^,_^,^  „£  .o^o. 
coronite,  has  the  ratios,!  .8  .  &,  ^,„y  ^^  called 

The  black  fervo-inagne-an^P  -  ^^^^^^^  species,  aphr. 
sehorlite,  gives  1;  *  •  6.  the  ^^^^^j^^^  i .,  12  15 

7ite  li6:8;  in<l'«o^'te,  1  •«  •  i-'  j^s  are  chiefly 

Th    protoxyd-bases  in    b.  la     tw^J^^  ^^  ^^^.^ 

alkalies,  in  large  P^J^^^tuh  t^e  Kthia-bearing  micas  oi 
nects  these  tourmaUnes  vvitl 

the  granitic  veins  in  ^^-f  \7j„o,tio„  of  ferric  oxyd  re- 
*i,?all  of  these  tourmaline^  a^oif    Mitscherhch 

places    alumina.     The    det*  »  .^  ^^v,„,i,te  and 

Sdng  a  larger  amoun     of  tiie^  ^    Rammels- 

:^iite  in  the  ferrous  sU     than  s  W^  ^^  ^,^^ 
bevE,  will,  if  admitted,  bung        o^ygen-ratios  of  mdic" 
Serto  that  of  0°-"*.  J'-  °^4%.e  the  same  w^ 
lite  as  pointed  out  by  Kam'  damourite  amJ 

tho'se  o    the  micas  des.gnat«l  ^^^^  ^j  „bellite 

p  "  go-*^-  "^"^'^  "*"T:tlready  mentioned  (which  are 
Ll  the  Rozenatourmahne  already  j^   ^^^  „;  tl, 

1.1^.  21)  are  the  ratios  of   the  i  ^^  .^  ^^.^i^„t 

.  ;;ece'din  '  table    which  ^^^^  genesis  of  tliese 

that   all  that  has  been  saia  a  tourmar.ncs.      H'S 

»^-  >^  ^^^^J^t^r  -^  —  of  the  various  tour- 
constitution  and  tne  a 


t>i 


THE   CRENITIC   HYPOTHESIS. 


163 


malines  will  be  found  discussed  at  length  in  Essay  VIII., 
§§  85,  86.] 

§  104.  There  exists  an  important  class  of  hydrous 
alkaline  aluminous  silicates,  related  to  the  muscovitic 
micas  in  composition,  but  differing  widely  from  them  in 
structure  and  physical  characters.  It  includes  what  has 
been  variously  designated  as  pinite,  gieseckite,  agalmato- 
lite,  and  dysyntribite,  which  sometimes  occur  in  crystal- 
line forms  in  other  rocks,  and  at  other  times  themselves 
constitute  rcck-masses.  Amorphous,  and  granular  or 
compact  in  texture,  its  hardness  and  general  aspect  liave 
often  led  observers  to  compare  it  to  serpentine.  The 
many  varieties  of  this  substance,  as  D:.iia  has  remarked, 
agree  closely  in  physical  characters,  as  well  as  in  composi- 
tion, and  he  has  deduced  from  their  analyses  a  formula 
corresponding  to  a  hydrous  silicate  of  potash  and  alumina, 
with  the  ratios,  1  :  8  :  12  :  3,  which  requires  potash  12.0, 
alumina  35.1,  silica  46.0,  water  6.9  =  100;  in  which  the 
po.tash  may  be  partially  replaced  by  soda,  lime,  or  magne- 
sia. Dysyntribite,  as  first  described  by  C.  U.  Shepard, 
forms  rock-masses,  associated  with  specular  hematite,  in 
St.  Lawrence  county.  New  York ;  and  similar  deposits, 
often  of  considerable  extent,  occur  in  the  crystalline 
schists  of  the  Green  Mountain  range,  both  in  Vermont 
and  Quebec.  In  the  latter  province,  a  bed  of  it  in  Stan- 
stead,  interstratified  with  chloritic  schists,  is  one  hundred 
and  fifty  feet  wide,  schistose,  and  often  with  an  admixture 
of  quartz.  Layers  of  the  pure  pinite  from  this  deposit, 
formerly  described  by  the  writer  under  the  synonym  of 
agalmatolite,  have  a  banded  structure,  a  ligneous  aspect, 
and  a  satiny  lustre.  The  mineral  is  translucent,  soft, 
unctuous,  and  somewhat  resembles  steatite.  A  similar 
deposit  occurs  in  argiliite,  among  the  crystalline  schists  of 
St.  Francis,  Beauce,  which  is  honey-yellow  in  color,  and 
granular  in  texture.  The  pinites  from  these  two  locali- 
ties agree  closely  in  composition.  That  of  the  latter  con- 
tained silica  50.50,  alumina  33.40,  magnesia  1.00,  potash 


I 


nr   i;:!l 


(.ill;  I 


164 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


tv. 


8.10,  soda  0.G3,  water  5.36  (with  traces  of  lime  and  iron- 
oxyd)  =  98.99.  These  elements  give  almost  exactly  the 
oxygen-ratio  of  1:8:  13|  :  2^,  closely  agreeing  with 
Dana's  formula,  except  in  an  excess  of  silica,  perhaps  due 
to  an  admixture  of  quartz,  which  is  apparent  in  the 
deposit  at  Stanstead.*  I'he  variety  of  pinite  formerly 
described  by  the  writer  as  parophite,  from  its  resemblance 
to  serpentine,  occurs  in  uncrystalline  Cambrian  shales  at 
St.  Nicholas,  near  Quebec,  f  Related  to  pinite  are  the 
minerals  which  have  been  called  onkosine  and  oosite. 

The  name  of  cossaite  has  been  given  to  a  similar  min- 
eral having  the  physical  characters  of  pinite,  from  which 
it  differs  in  containing  soda  instead  of  potash.  The 
formula  which  has  been  deduced  from  its  analysis,  is 
identical  with  that  of  the  soda-mica,  paragonite.  We 
cannot  be  certain,  in  the  case  of  massive  minerals  like 
these,  whether  this  same  general  formula  is  not  as  well 
adapted  to  pinite  as  that  proposed  above.  In  any  case,  it 
is  evident  that  we  have  in  the  pinitic  group  a  widely  dis- 
tributed class  of  natural  silicates,  not  less  important  than 
the  muscovitic  group,  and  probably  similar  in  origin. 

§  105.   The    constancy  in   composition  and  the  wide 

*  See,  for  an  account  of  these  various  forms  of  pinite,  there  described 
AS  agalniatolite,  the  Geology  of  Canada,  1863,  pp.  484,  485. 

t  There  are  several  other  hydrous  silicates  of  alumina,  sometimes 
with  alkali,  which,  like  pinite,  are  sometimes  found  among  uncrystalline 
strata,  showing  that  the  conditions  of  their  deposition  have  been  con- 
tinued down  to  comparatively  recent  times.  Such  is  the  bravaisite  de- 
scribed by  Mallard,  a  soft  unctuous  matter,  with  a  fibrous  texture,  occur- 
ring in  layers  in  shales  of  the  coal-measures  in  France.  It  is  a  hydrous 
silicate  of  potash  and  alumina,  with  a  little  lime  and  magnesia,  and 
according  to  its  author,  after  deducting  impurities,  gives  essentially  the 
ratios,  1:3:9:4.  The  hygrophilite  of  Laspeyres  is  also  a  soft,  unctuous, 
cryptocrystalline  matter,  found  in  sandstone,  which  somewhat  resembles 
bravaisite,  and  is  compared  to  pinite.  It  contains  potash  and  some  soda, 
and  gives  the  ratios,  1:5:9:3.  A  somewhat  similar  substance,  found  re- 
placing coal-plants  in  the  Tarentaise,  has  been  also  referred  to  pinite  or 
to  the  so-called  giimbellite.  Genth,  on  the  other  hand,  found  pyrophyl- 
lite  replacing  the  substance  of  coal-plants  in  Pennsylvania.  (See  Dana's 
System  of  Mineralogy,  Supplements,  I.,  6;  II. ,29,  63;  and  III.,  18,  54). 
Also  farther,  Essay  Y I. ,  respecting  bamelite,  glauconite,  and  related  sili- 
cates. 


are 


▼.J 


THE  CUENITIO  HYPOTHESIS. 


165 


distribution  of  pinite  show  it  to  be  a  compound  readily 
formed  and  of  great  stability.  Such  being  its  character, 
it  might  be  expected  to  occur  as  a  frequent  jjrodiict  of  the 
aqueous  changes  of  other  and  les  table  silicates.  It  is 
met  with  in  veinstones,  in  the  shape  of  crystals  of  neplie- 
lite,  iolite,  scapolite,  feldspars,  and  spoduniene,  from  each 
of  which  it  is  supposed  to  have  been  formed  b}-  epigene- 
sis.  Its  frequent  occurrence  as  an  epigenic  product  is  one 
of  the  many  examples  to  be  met  with  in  the  mineral  king- 
dom of  the  law  of  "  the  survival  of  the  fittest."  It  is, 
however,  difficult  to  assign  such  an  origin  to  beds  of  this 
mineral  like  those  which  have  been  above  described, 
which  are  probably  the  results  of  original  depojition  or  of 
diagene^'o.  It  is  (?.  characteristic  of  our  present  unnatural 
system  of  mineralogy  to  banish  to  the  category  of  doubtful 
species  most  of  the  substances  which  are  sipposed  to  be 
of  epigenic  origin,  and  which  do  not  ordinarily  present  a 
definite  crystalline  structure.  Several  mineral  compounds 
are  apparently  indispcjsed  to  assume  a  crystalline  condi- 
tion, and  among  these  are  pinite  and  serpentine.  The 
latter  is  probably,  like  pinite,  in  certain  cases,  a  product 
.of  epigenesis;  but  few,  we  think,  who  have  studied  the 
mode  of  its  occurrence  and  distribution  in  crystalline 
limestones,  will  ascribe  to  it,  in  such  conditions,  an  epi- 
genic origin. 

§  106.  Dana  has  compared  serpentine  and  pinite  on  the 
ground  of  their  phj'sical  resemblances,  and  has  said  that 
pinite  is  "an  alkali-alumina-serpentine,  as  pyrophyllite  is 
an  alumina-talc."*  The  relations  between  the  minerals 
thus  compared  are,  however,  mimetic  only  and  not 
genetic.  A  true  system  of  mineralogical  classification 
must  not  be  based  on  analogies  such  as  these,  nor  on 
assumptions  regarding  water  as  replacing  fixed  bases,  or 
alumina  as  taking  the  place  on  the  one  hand  of  silica  or 
on  the  other  of  protoxyd-bases.  Some  of  the  relations 
suggested  by  formulas  constructed   in   accordance  with 

♦  Dana's  System  of  Mineralogy,  5tli  ed.,  p,  479. 


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23  WEST  MAIN  STREET 

WEBSTER,  N.Y.  14580 

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166 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


1^ 


such  assumptions,  are  not  without  interest  from  the  point 
of  view  of  theoretical  chemistry,  but  serve  only  to  mislead 
the  mineralogist  who  seeks  for  a  fundamental  and  genetic 
system  of  classification  of  mineral  silicates. 

§  107.  The  cardinal  distinction  is  that  between  pro- 
toxyd-silicates  and  aluminous  silicates,  based  on  their 
origin  and  on  the  chemical  relations  of  their  respective 
bases.  For  the  latter  class  there  comes,  in  the  next  place, 
the  consideration  of  the  proportions  between  the  protoxyd- 
bases  and  the  alumina,  and  the  departures  on  either  side 
from  the  ratio,  R, :  al  =  1 : 3,  as  seen  in  the  relations  of 
those  aluminous  silicates  with  an  excess  of  R,  on  the  one 
hand,  and,  on  the  other,  those  with  a  deficiency  of  R, 
which  are  connected  with  the  simple  aluminous  silicates. 
The  above  ratio  of  1:3,  which  we  have  called  the  normal 
ratio  of  protoxyd  to  alumina,  is  that  not  only  of  the  feld- 
spars and  the  zeolites,  but  of  diaspore,  of  the  spinels,  and 
of  the  crystalline  aluminate  of  potash.  The  chemist  will 
not  need  to  be  reminded  t'lat  this  stable  group  is  the  sim- 
plest possible  compound  which  the  hexatomic  element, 
aluminium,  can  form  with  a  monatomic  or  a  diatomic  ele- 
ment like  sodium  or  calcium,  corresponding  to  a  condensed 
molecule  the  water-type  of  which  will  be  H8O4. 

§  108.  The  point  of  next  importance,  which  is  of  spe- 
cial significance  in  the  aluminous  double  silicates,  is  that 
of  their  greater  or  less  condensation,  or,  in  other  words, 
the  relation  of  their  density  to  their  empirical  equivalent 
weight,  as  already  pointed  out  in  the  case  of  the  scapolite 
and  epidote  groups  (§  81).*  The  greater  stability  of 
those  which  belong  to  the  more  condensed  types  is  shown 
in  their  superior  resistance  to  decay,  and  is  thus  of  geolog- 
ical significance.  The  relations  of  anhydrous  to  hydrous 
species  of  aluminous  double  silicates  appear  to  be  of  less 
importance  when  we  consider  what  secondary  causes  will 

*  See,  in  this  connection,  the  author  On  the  Objects  and  Method  of 
Mineralogy,  Chem.  and  Geol.  Essays,  pp.  452-458;  also  the  same,  pp. 
445-447,  and  farther  in  Essay  VIII.,  passim. 


pc 
wd 
lei 

bJ 
shl 
gel 

aul 


v.] 


THE  CRENITIC  HYPOTHESIS. 


167 


determine  the  formation  either  of  a  hydrous  or  an  anhy- 
drous species,  of  a  zeolite  or  a  feldspar.f  The  relations 
of  the  bases,  potash,  soda,  and  lime,  to  each  other,  and  to 
magnesia  and  other  protoxyd-bases,  are  next  to  be  consid- 
ered, alike  for  th6  double  aluminous  silicates  and  for  simple 
silicates  of  protoxyds. 

A  system  of  classification,  constructed  in  accordance 
with  these  principles,  has  already  been  indicated  in  the 
preceding  illustrations  of  the  crenitic  hypothesis,  and  will, 
it  is  believed,  be  found  of  fundamental  importance  for  the 
student  of  mineral  physiology;  since  it  is  based  on  the 
genetic  processes  by  which  the  species  of  the  mineral 
kingdom  have  in  most  cases  been  formed.  The  principles 
which  it  embodies' will  be  found  not  less  applicable  to 
compounds  of  igneous  origin  than  to  those  formed  by 
aqueous  processes.  Such  a  system  of  classification  is 
developed  farther  on,  in  Essay  VIII. 

§  109.  In  considering  the  origin  of  crystalline  stratified 
rocks  formed,  in  accordance  with  our  hypothesis,  in  all 
cases  with  tlie  concurrence  of  water,  questions  connected 
with  the  process  of  crystallization  of  mineral  species,  and 
of  their  condition  when  first  deposited,  are  of  much  impor- 
tance. The  most  familiar  case  is  that  of  the  direct  separa- 
tion of  matters  in  a  crystalline  condition,  as  happens  from 
the  evaporation  or  the  change  of  temperature  of  the  sol- 
vent, or  from  the  generation  of  new  and  less  soluble  com- 
pounds, as  in  many  cases  of  chemical  precipitation.  In 
this  connection,  it  should  be  noted  "  that  many  such  com- 
pounds, when  first  generated  by  double  decomposition  in 
watery  solutions,  remain  dissolved  for  a  greater  or  less 
length  of  time  before  separating  in  an  insoluble  condition. 
.  .  .  There  is  reason  to  believe  that  silicates  of  insoluble 
bases  may  assume  a  similar  state,  and  it  will  probably  be 
shown  one  day  that  for  the  greater  number  of  those  oxy- 
genized compounds,  which  we  call  insoluble,  there  exists 

t  On  the  relations  of  hydrous  to  anhydrous  species,  see  farther  the 
author  in  Essay  X.,  §  117-118. 


h:     :•! 


iK  irl^''l■■ 


168 


THE  ORIGIN  OP  CEYSTALLINE  EOCKS. 


tv. 


a  modification  soluble  in  water.  In  this  connection  also 
may  be  recalled  the  great  solubility  in  water  of  sili'^ic, 
titanic,  stannic,  ferric,  aluminic,  and  chromic  oxyds,  when 
in  what  Graham  has  called  the  colloidal  state."  *  In  writ- 
ing the  above,  in  1874,  reference  was  also  made  to  my 
own  earlier  observations  on  the  solubility,  under  certain 
conditions,  of  carbonate  of  lime,  which  are  subjoined. 

§  110.  "  The  recent  precipitate  produced  by  a  solution 
of  carbonate  of  soda  in  chlorid  of  calcium  is  readily  solu- 
ble in  an  excess  of  the  latter  salt,  or  in  a  solution  of  sul- 
ph-^ce  of  magnesia.  The  transparent,  almost  gelatinous 
magma,  which  results  when  solutions  of  carbonate  of  soda 
and  chlorid  of  calcium  are  first  mingled,  is  immediately 
dissolved  by  a  solution  of  sulphate  of  magnesia,  and  by 
operating  with  solutions  of  known  strength  [titrated  solu- 
tions] it  is  easy  to  obtain  transparent  liquids  holding  in  a 
litre,  besides  three  or  four  hundredths  of  hydrated  sul- 
phate of  magnesia,  0.80  gramme,  and  even  1.20  grammes, 
of  carbonate  of  lime,  together  with  1.00  gramme  of  car- 
bonate of  magnesia ;  the  only  other  substance  present  in 
the  water  being  the  chlorid  of  sodium  equivalent  to  these 
carbonates.  A  solution  of  chlorid  of  magnesium,  holding 
some  chlorid  of  sodium  and  sulphate  of  magnesia,  in  like 
manner  dissolved  1.00  gramme  of  carbonate  of  lime  to  the 
litre.     Such  solutions  have  an  alkaline  reaction." 

These  solutions,  which  contained  in  all  cases  neutral 
carbonates  with  no  excess  of  carbonic  acid,  possessed  a 
considerable  degree  of  stability.  One  prepared  with  0.80 
gramme  of  carbonate  of  lime  and  1.00  gramme  of  carbo- 
nate of  magnesia,  when  filtered  after  standing  eighteen 
hours  at  10°  C,  still  retained  0.72  gramme  of  carbonate 
of  lime  to  the  litre,  but,  after  some  days,  deposited  the 
whole  of  this  in  transparent  crystals  of  hydrous  car- 
bonate of  lime,  all  of  the  carbonate  of  magnesia  remain- 
ing dissolved.  This  hydrous  carbonate,  stable  at  low  tem- 
peratures, is  at  once  decomposed,  with  loss  of  its  water,  at 
*  Hunt,  Chem.  and  Geol.  Essays,  p.  223.      •'''    ,     -       ■ 


30°  ( 

Date 

upon 

pie  o; 

so-cal 

consij 

the  sa 

the  so 

of  tlie 

[An 

tion  oi 

Engel 

same  ci 

ural  (a 

it  slow 

and  ev€ 

such  a  ] 

respects 
.  got  by 
talline  ' 
potassic 
carbonic 
mingled 
water,  f  1 

§  lllj 

precipitg 

ticed. 
a  remarl 
in  the  cl 
got  by  id) 
in  tlie  cc 
obtained 
crystalliij 
notable 

*  Hunt, 
Part  II.,  igJ 

t  ComptI 


w^\ 


▼.] 


THE  CRENITIO  HYPOTHESIS. 


169 


30°  C.  "  The  solubility  of  the  yet  uncondensed  carbo- 
nate of  lime  in  neutral  solutions,  which  are  without  action 
upon  it  in  another  state  of  aggregation,  is  a  good  exam- 
ple of  the  modified  relations  presented  by  bodies  in  the 
so-called  nascent  state,  which  probably^  as  in  this  case, 
consists  of  a  simpler  and  a  less  condensed  molecule.  At 
the  same  time,  the  gradual  spontaneous  decomposition  of 
the  solutions  thus  obtained  affords  an  instructive  instance 
of  the  influence  of  time  on  chemical  changes."  * 

[Another  instructive  instance  of  an  isomeric  modifica- 
tion of  a  carbonate  is  afforded  by  the  late  discovery  by 
Engel  of  an  anhydrous  magnesian  carbonate  having  the 
same  centesimal  composition  as  the  dense  insoluble  nat- 
ural (and  artificial)  rhombohedral  carbonate,  but  unlike 
it  slowly  absorbing  water  to  form  crystalline  hydrates, 
and  even  soluble  in  water,  giving  a  solution  from  which 
such  a  hydrated  carbonate  crystallizes ;  recalling  in  these 
respects  the  soluble  lime-carbonate  just  described.  It  is 
got  by  decomposing,  between  70°  and  150°  C,  the  crys- 
talline hydrous  compound  of  magnesian  carbonate  and 
potassic  acid- carbonate,  the  water  and  one-fourth  the 
carbonic  acid  being  expelled.  The  new  carbonate  remains 
mingled  with  potassium  carbonate,  which  is  removed  by 
water,  f] 

§  111.  The  spontaneous  conversion  of  uncrystalline 
precipitates  into  crystalline  aggregations  may  next  be  no- 
ticed. Instances  of  this  are  well  known  to  chemists,  but 
a  remarkable  and  hitherto  undescribed  example  is  afforded 
in  the  case  of  the  mixed  oxalates  of  the  cerium-metals, 
got  by  precipitating  their  nitric  solution  with  oxalic  acid 
in  the  cold.  A  tough  pitchy  mass  was  thus  repeatedly 
obtained  which,  in  a  few  minutes,  changed  into  incoherent 
crystalline  grains,  the  conversion  being  attended  with  a 
notable  evolution  of  heat.    Another  example  of  a  some- 

*  Hunt,  Contributions  to  the  History  of  Lime  and  Magnesia  Salts; 
Part  II.,  1866.    Amer.  Jour.  Science,  vol.  xlii.,  pp.  58,  59 

t  Compte  Rendu  de  I'Acad.  des  Sciences,  October  26,  1885,  p.  814. 


I-. 


,HE  OBIGINOir  CUV8TAI.I.IKB  BOCKS. 


■ff» 


1  ^v--r-\:^^  :.XT^:^ 

lorphous  !"-'"•!  !'::^iV  into  cry^ls  beneath  the 
known,  spontaneously  ctouge 

Wa  in  which  .t  has  be  -J-^^^^,  „„  ,he  -Its  of  me 


"^  In  which  it  has  been  V^-^^^-  ,,,  ,ats  of  Ume 

^S  112.  In  the  paper  above  qnotea  ^^  ,„„,. 

and  magnesia,  I  have  desc.*ed  not  e^  ^^  ^^^^  ^^,.j,„. 

Is  rf  similar  transfonnafons  .n  the  ^^^,^^„,t, 

ttes  of  lime  and  magnes.a.  A  p^.te  "  J  ^^^^^^ 

of    magnesia  P'«T  * t  "neratures,  into  a  cvysta Ume 
under  water,  at  ordmary  tempera        ^_^^.^^^  ,gg,egatrons, 

mass  made  up  of  pr>sms^  S  ""^^'^  '       ,esian  carbonate.    In 
of  the  well-known  terhy-l  ate'l  »»?  trfturating  .n  a 

iL  manner,  the  ^^'j  '"rids  ^f  calcium  and  magnesium, 
mortar  a  solution  of  eUo^^s  ot  c  ^^^^^^^   j  , 

i„  equivalent  P™Pf*'"*  :'tr„f   o^a- 's,  at  a  tempc^ture 
solution  of  neutral  carbonate  oi  ^^^^^^^^  j„to  an 

S"rom  65'  to  80°  C.  » -"^ed,  a^     ^^^^^  ^^  ^ 
aggregate  of  translucent  ovystaU^  hJ,odolomite  of  Von 
dfuble  carbonate,  vesembln  g  *be  hy  ^^  ^^,  ^^  ^      ^^^^^ 
KobeU.     At  tempera  uieot  ^^^^^^        . 

magma  changes  slowly  u  to  am  ,^^  ^,     i,es    from 

pound.    The  process  °«    f  »f;„ed  "to  consist  m  the 
Welvc  to  twenty-five  days  app^^^.^^^.^^  ^^^^^^^^ 

formation  of  nuclei  «"»  f '^^  voluminous,  opaque,  and 
until  every  particle  ««  ^^^^^^^  translucent,  dense,  and 
amorphous  precipitate  had  b  'Jom  ^^  ^^^^^^^  ^^^^^ 

crystalline."     The  product  is  made    P  ^^^  ^^^^. 

apparently  oblique,  grouped  —  ;„  dimeter. 

Zes  forming  spheres  6™  °"'^   ^j  u^e  and  magnesia, 
■       The  hydrated  double  ^^^^^\^,,,,  of  carbonate  of 
thus  formed  ^  presenc   oJ  a  si  g         ^^^        ^^„,  „(  ,u 
soda,  was  found  to  »»"*»  ^^^^ether  this  did  not  proceed 
latter,  but  it  wa^  "»*  f'^Ja^us  double  carbona  e  of 
from  an  admixture  of  the  hya  ,„„bination  itself 

Ume  and  soda,  Sf  "t^;^'!  Jeomposition  of  a  gayluss'te 
was  described  as  having  «»»P  ^^^  production 

in  which  magnesium  leplaees 


v.] 


THE  CRENITIC  HYPOTHESIS. 


171 


of  crystals  of  true  gaylussite,  as  observed  by  Fiitzsche, 
by  the  slow  crystallization  of  the  gelatinous  precipitate 
got  when  a  strong  solution  of  carbonate  of  soda  in  excess 
is  mingled  with  one  of  calcium-chlorid,  is  another  remark- 
able example  of  the  phenomenon  under  consideration. 

Fritzsche  moreover  observed  that  it  is  not  necessary 
that  the  lime-carbonate  should  be  in  its  gelatinous  form 
in  order  to  produce  this  compounl,  since  the  previously 
precipitated  carbonate,  when  digested  with  a  solution  of 
carbonate  of  soda,  slowly  combines  with  it  to  form  the 
crystalline  hydrous  double  salt.  J/Iore  remarkable  still  is 
the  observation  of  H.  Ste.-Claive  Deville,  which  I  have 
repeatedly  verified,  that  a  paste  of  magnesia  alba  and  bi- 
carbonate of  soda,  with  water,  is  slowly  changed,  at  a 
temperature  of  from  60°  to  70°  C,  into  a  transparent 
crystalline  anhydrous  double  carbonate  of  lime  and  soda, 
rhombohedral  in  form,  and  called  by  its  discoverer  a  soda- 
dolomite.* 

§  113.  In  this  connection,  it  should  be  said  that  we 
have  here  an  explanation  of  the  formation  of  the  double 
carbonate  of  lime  and  magnesia  which  constitutes  ordi- 
nary dolomite.  The  origin  of  this  mineral  ^ecies,  which 
so  often  constitutes  rock-masses,  is  still  generally  misun- 
derstood. The  baseless  notion  of  its  production  by  a 
metasomatosis  or  partial  replacement  of  the  lime  in  ordi- 
nary limestone,  imagined  by  the  older  geologists,  is  still 
repeated,  and  holds  its  place  in  the  literature  of  the  sci- 
ence despite  the  facts  of  geognosy  and  of  chemistry.  I 
have  long  since  shown,  bj'^  multiplied  examples,  that  the 
ordinary  mode  of  the  occurrence  of  dolomite  in  nature  is 
not  in  accordance  with  this  hypothesis  of  its  origin,  since 
beds  of  dolomite,  or  more  or  less  magnesian  limestone, 
are  found  alternating,  sometimes  in  thin  and  repeated 
layers,  with  beds  of  non-magnesian  carbonate  of  lime. 
Moreover,  beds  of  crystalline  dolomite,  conglomerate  in 

*  Hunt,  Contributions  to  the  History  of  Lime  and  Magnesia  Salts; 
Part  II.,  1866.    Amer.  Jour.  Science,  vol.  xlii.,  pp.  54-57. 


172 


THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 


m 


lip' 


character,  are  found  to  enclose  pebbles  and  fragments  of 
pure  non-magnesian  carbonate  of  lime.  I  have  also  ex- 
plained at  length  the  natural  reactions  by  which  precipi- 
tates consisting  of  a  greater  or  less  proportion  of  hydrous 
carbonate  of  magnesia,  mixed  with  carbonate  of  lime, 
must,  in  past  ages,  have  been  laid  down  in  the  waters  of 
lakes  and  inland  seas,  in  some  cases  with,  and  in  others 
without,  the  simultaneous  formation  of  sulphate  of  lime. 

It  was,  moreover,  found  that  the  reaction  at  an  elevated 
temperature  in  presence  of  water,  between  sulphate  of 
magnesia  and  an  excess  of  carbonate  of  lime,  supposed  by 
Haidinger  and  Von  Morlot  to  explain  the  frequent  asso- 
ciation of  gypsum  and  dolomite,  does  not  yield  the  double 
carbonate,  since  the  carbonate  of  magnesia  separates  in  an 
anhydrous  form,  and  does  not  combine  with  the  carbonate 
of  lime.  Finally,  it  was  shown  that  mixtures  of  hydrous 
carbonate  of  magnesia  and  carbonate  of  lime,  when  heated 
^.  :ether  in  presence  of  water,  unite  to  form  the  anhydrous 
double  carbonate  which  constitutes  dolomite.  In  my  ex- 
periments, their  combination,  with  the  formation  of  dolo- 
mite, was  effected  rapidly,  at  120"  C,  but  many  consid- 
erations lead'  to  the  conclusion  that  its  production  in 
nature  is  effected  slowly  at  much  lower  temperatures,  and 
that  the  formation  of  the  hydrous  double  carbonate  already 
described  is,  perhaps,  an  intermediate  stage  in  the  pro- 
cess.* The  existence  of  a  soluble  and  active  form  of  mag- 
nesian  carbonate,  as  described  in  §  110,  throws  an  addi- 
tional light  upon  the  formation  of  dolomite. 

§  114.  The  reactions  described  in  the  preceding  para- 
graphs between  the  elements  of  comparatively  insoluble 
substances  in  the  presence  of  water,  resulting  not  only  in 
the  conversion  of  amorphous  into  crystalline  bodies,  but 
in  the  breaking-up  of  old  combinations,  as  well  as  in  the 
union  of  unlike   matters  mechanically  mingled  t     form 

*  Hunt,  Contributions  to  the  Ciiemistry  of  Lime  and  Magnesia,  part 
i.,  1859,  Amer.  Jour.  Sci.,  xxviii.,  pp.  170,  365;  and  part  ii.,  1806,  ibid,, 
vol.  xii.,  p,  49;  also  in  abstract  in  Cheiu.  and  Geol.  Essays,  pp.  80-92.    . 


is  thi 

grain^ 

chemj 

takes 

tallini 


v.] 


THE  CRENITIC  HYPOTHESIS. 


178 


new  crystalline  species,  are  instructive  examples  of  what 
Giimbel  has  termed  diagenesis.  The  changes  in  the 
masonry  of  the  old  Roman  baths  in  contact  with  thermal 
waters,  resulting  in  the  hydration  of  the  substance  of  the 
bricks,  and  its  conversion  into  zeolitic  minerals;  the 
hydration  of  volcanic  glasses  with  similar  results,  going 
on,  even  at  low  temperatures,  in  the  deep  sea ;  the  decom- 
position of  common  glass  by  heated  water ;  the  conversion 
of  basaltic  rock  into  palagonite,  and  the  production  there- 
from of  zeolites;  the  similar  changes  seen  elsewhere  in 
amygdaloids,  and  even  in  massive  basic  plutonic  rocks, 
are  also  examples  of  this  process  of  diagenesis,  and  serve 
to  show  its  great  geological  significance.  We  have  already 
suggested  the  intervention  of  similar  reactions  in  past 
ages  among  the  sediments  from  the  sub-aerial  decay  of 
feldspathic  rocks,  in  some  cases  with  the  concurrence  of 
the  secretions  from  the  primary  basic  stratum,  which,  in 
accordance  with  the  crenitic  hypothesis,  we  suppose  to 
have  been  the  source  of  soluble  mineral  silicates.  In  the 
diagenesis  of  these  early  argillaceous  sediments,  aided  by 
crenitic  action,  will,  it  is  believed,  be  found  the  origin  of 
many  of  the  crystalline  schists  of  the  Transition  rocks. 

§  115.  An  instructive  phase  in  this  diagenetic  process 
is  that  of  the  gradual  conversion  of  smaller  crystalline 
grains  or  crystals  into  larger  ones,  which  is  familiar  to 
chemists.  This  action  is  in  fact  nearly  akin  to  that  which 
takes  place  in  the  transformation  of  amorphous  into  crys- 
talline precipitates,  since  in  both  cases  a  partial  solution 
precedes  the  crystallization.  It  is  well  known  that,  as  a 
result  of  successive  solution  and  redeposition,  large  crys- 
tals may  be  built  up  at  the  expense  of  smaller  ones.  To 
quote  the  author's  language  of  fifteen  years  since,  this 
process,  as  H.  Deville  has  shown,  "  suffices,  under  the  in- 
fluence of  the  changing  temperature  of  the  seasons,  to 
convert  many  fine  precipitates  into  crystalline  aggregates, 
by  the  aid  of  liquids  of  slight  solvent  powers.  A  similar 
agency  may  be  supposed  to  have  effected  the  crystalliza- 


:^K 


"|, 


pB|| 


K^ ;. !' 


r-' 


174 


THE  ORIGIN  OF  CRYSTALLINE   ROCKS. 


tion  of  buried  sediments,  and  changes  in  the  solvent  power 
of  the  permeating  water  might  be  due  either  to  variations 
of  temperature  or  of  pressure.  Simultaneously  with  tliis 
process,  one  of  chemical  union  of  heterogeneous  elements 
may  go  on,  and  in  this  way,  for  example,  we  may  suppose 
that  the  carbcriates  of  lime  and  magnesia  become  united 
to  form  dolomite  or  magnesian  limestone."  * 

§  116.  The  tendency  of  the  dissolved  material  in  this 
process  to  crystallize  around  nuclei  of  its  own  kind,  rather 
than  on  foreign  particles,  is  a  familiar  fact,  and  its  geolog- 
.  ical  importance,  to  which  I  first  called  attention,  as  above, 
in  1869,  was  again  pointed  out  by  Sorby  in  1880,  when  he 
showed  that  dissolved  quartz  might  be  deposited  upon 
clastic  grains  of  this  mineral  in  perfect  optical  and  crys- 
tallographic  continuity,  so  that  each  broken  fragment  of 
quartz  is  changed  into  a  definite  crystal,  as  was  seen  in 
his  microscopic  studies  of  various  sandstones.f  Tliis  fact 
has  been  confirmed  by  the  observations  of  Young,  Irving, 
and  Wadsworth  in  the  United  States ;  J  and  Bonney  has 
suggested  the  possible  extension  of  such  a  process  to  feld- 
spar, hornblende,  and  other  minerals.  § 

Vanhise  has  very  recently  announced  that  his  micro- 
scopical examinations  of  certain  sandstones  of  the  Kewee- 
nian  series,  from  Lake  Superior,  afford  evidence  of  the 
secondary  deposition  of  both  orthoclase  and  plagioclase 
feldspar,  in  crystallographic  continuity,  upon  broken  feld- 
spathic  grains,  in  one  case  uniting  the  two  parts  of  p 
broken  feldspar-crystal.  The  sandstones  which  have 
yielded  these  examples  are  made  up  in  part  of  feldspathic 
fragments,  and  in  part  of  fragments  of  "  some  altered  basic 
rocks."     They  are,  moreover,  interstratified  with  and,  in 

*  Hunt,  The  Chemistry  of  the  Earth,  Report  of  Smithsonian  Institu- 
tion, 1869;  also  Chem.  and  Geol.  Essays,  p.  306. 

t  Sorby,  Presidential  Address,  Quar.  Jour.  Geo.  Soc.  London,  xxxvi., 
83. 

t  Young,  Arner.  Jour.  Sci.,  xxiv.,  47.  Irving,  ibid.,  xxv.,  401.  Wads- 
worth,  Proc.  Boston  Soc.  Natural  History,  Feb.  7,  1883. 

§  Bonney,  Quar.  Jour.  Geol.  Soc,  xxxix.,  19. 


T.1 


THE  CRENITIC  HYPOTHESIS. 


175 


some  cases  at  least,  immediately  underlie  the  basic  plu- 
tonic  rocks  of  the  same  Keweenian  series.*  When  we 
consider  that  orthoclase  is  a  common  secretion  of  these 
basic  rocks,  as  is  shown  by  its  frequent  occurrence  in 
them  with  zeolites  and  epidote,  it  may  perhaps  be  ques- 
tioned whether  the  secondary  feldspar  in  the  sandstone 
has  been  derived  from  the  adjacent  grains  of  this  mineral, 
or  has  come  into  solution  from  the  transformation  of  the 
basic  rocks.  The  apparent  stability  and  insolubility  of 
orthoclase  and  oligoclase  at  high  temperatures  in  the  pres- 
ence of  water,  as  observed  by  Daubr6e,  wouhl  seem  to 
favor  the  latter  view.  In  any  case,  it  is  a  striking  illus- 
tration of  the  tendency  of  mineral  species  to  crystallize 
around  nuclei  of  their  own  kind,  which  is  so  marked  a 
factor  in  the  development  of  the  crystalline  rocks. 


IV. 


■CONCLUSIONS. 


§  117.  We  reviewed  in  the  first  part  of  this  essay  the 
history  of  the  different  hypotheses  hitherto  proposed  to 
explain  the  origin  of  the  crystalline  rocks,  and,  in  doing 
so,  reached  the  conclusion  that  not  one  of  them  affords  an 
adequate  solution  of  the  various  problems  presented  by 
the  chemical,  mineralogical,  and  geognostical  characters 
of  the  rocks  in  question ;  at  the  same  time,  we  endeavored 
to  show  succinctly  what  are  the  principal  conditions  to 
which  a  satisfactory  hypothesis  must  conform.  In  the 
second  part,  we  sketched  the  growth  and  development, 
during  the  last  quarter  of  a  century,  of  what  we  believe 
to  be  such  a  hypothesis.  In  the  third  part,  we  sought  to 
bring  together  a  great  number  of  facts,  both  new  and  old, 
which  serve  to  illustrate  the  new  hypothesis ;  according 
to  which  the  crystalline  stratiform  rocks,  as  well  as  many 
erupted  rocks,  are  supposed  to  have  been  derived  by  the 
action  of  waters  from  a  primary  superficial  layer,  regarded 
as  the  last  portion  of  the  globe  solidified  in  cooling  from  a 
state  of  igneous  fluidity.     This,  which  we  have  described 

*  Vanhise,  Amer.  Jo'ir.  Sci.,  1884,  xxvii.,  399. 


Ml 


176 


THE  OUIOIN  OF  CIIYSTALLINE  ROCKS. 


[V. 


.« 


as  a  basic,  quartzless  rock,  is  conceived  to  liave  been  fis- 
sured and  rendered  porous  during  crystallization  and 
refrigeration,  and  thereby  made  permeable,  to  consider- 
able depths,  to  the  waters  subsec^uently  precipitated  upon 
it.  Its  surface  being  cooled  by  radiation  while  its  base 
reposed  upon  a  heated  solid  interior,  upward  and  down- 
ward currents  would  establish  a  system  of  aqueous  circu- 
lation in  the  mass,  to  which  its  porous  but  unstratified 
condition  would  be  very  favorable.  The  materials  wiiich 
heated  subterraneous  waters  would  bring  to  the  surface, 
there  to  be  deposited,  would  be  not  unlike  those  which 
have  been  removed  by  infiltrating  waters  in  various  sub- 
sequent geological  ages,  from  erupted  masses  of  similar 
basic  rock ;  which,  we  have  reason  to  believe,  are  but  dis- 
placed portions  of  this  same  primary  layer.  The  mineral 
species  removed  from  these  latter  rocks,  or  segregated  in 
their  cavities,  are,  as  is  well  known,  chiefly  silica  in  the 
form  of  quartz,  silicates  of  lime  and  alkalies,  and  certain 
double  silicates  of  these  bases  with  alumina,  including 
zeolites  and  feldspars,  besides  oxyds  of  iron  and  carbonate 
of  lime ;  the  latter  species  being  due  to  the  intervention 
of  atmospheric  carbonic  acid.  The  absence  from  these 
minerals  of  any  considerable  proportion  of  iron-silicate, 
and,  save  in  rare  and  exceptional  conditions,  of  magnesia, 
is  a  significant  fact  in  the  history  of  the  secretions  from 
basic  rocks,  the  transformation  of  which,  under  the  action 
of  permeating  waters,  has  resulted  in  the  conversion  of 
the  dissolved  portion  of  the  material  into  quartz  and  vari- 
ous silicates  of  alumina,  lime,  and  alkalies,  while  leaving 
behind  a  more  basic  and  insoluble  residue  abounding  in 
silicated  compounds  of  magnesia  and  iron-oxyd  with 
alumina. 

§  11 8.  The  peculiarities  resulting  from  this  comparative 
insolubility  of  magnesian  silicates  long  ago  attracted  the 
attention  of  the  writer.  The  addition  to  solutions  like 
sea-water,  of  bicarbonate  of  magnesia,  which  is  a  product 
of  the  sub-aerial  decay  of  basic  rocks,  would,  it  was 


magn( 
the  atl 
renio) 

SOJid  II 

therefi 
^e  suj 
magnej 
Would  I 

*Ar 
P- 122. 


> 


TO 


THE  CRENITIC    HYPOTHESIS. 


177 


shown,  effect  a  separation  of  dissolved  lime-salts  in  tho 
form  of  carbonate,  leaving  the  nmgiie.sia  in  solution  as 
chlorid  or  as  8ul[)hate;  while  on  the  contrary  tho  reaction 
of  such  a  natural  water  with  certain  silicates,  whether 
solid  or  in  solution,  containing  lime  or  alkalies,  would 
effect  a  removal  of  the  dissolved  magnesia.  At  the  same 
time  it  was  shown  that  "by  digestion  at  ordinary  temper- 
atures with  an  excess  of  freshly  precipitated  silicate  of 
lime,  chlorid  of  magnesium  is  completely  decomposed,  an 
insoluble  silicate  of  magnesia  being  formed,  while  nothing 
but  chlorid  of  calcium  remains  in  solution.  It  is  clear 
that  the  greater  insolubility  of  the  magnesian  silicate,  as 
compared  with  silicate  of  lime,  determines  a  reaction  the 
very  reverse  of  that  produced  by  carbomites  with  solu- 
tions of  the  two  earthy  bases.  In  the  one  case,  the  lime 
is  separjited  as  carbonate,  the  magnesia  remaining  in  solu- 
tion, while  in  the  other,  by  the  action  of  silicate  of  soda, 
or  of  lime,  the  magnesia  is  removed  and  the  lime  remains. 
Hence  carbonate  of  lime  and  silicate  of  magnesia  are 
found  abundantly  in  nature,  while  carbonate  of  magnesia 
and  silicate  of  lime  are  produced  only  under  local  and 
exceptional  circumstances.  It  is  evident  that  the  produc- 
tion from  the  waters  of  the  early  seas  of  beds  of  sepiolite, 
talc,  serpentine,  and  other  rocks  in  which  a  magnesian 
silicate  abounds,  must,  in  closed  basins,  have  given  rise  to 
waters  in  which  chlorid  of  calcium  would  predominate."  * 
§  119.  From  this  reaction  it  would  follow  that  the 
magnesian  salts  formed  when  the  first  acid  wa.jrs  from 
the  atmosphere  fell  upon  the  primary  stratum,  would  be 
removed  from  solution,  either  by  the  direct  action  of  the 
solid  rock,  or  by  that  of  the  pectolitic  secretions  derived 
therefrom  in  the  earliest  ages.  The  primeval  ocean,  if,  as 
we  suppose,  a  universal  one,  would  soon  be  deprived  of 
magnesian  salts,  and  henceforth  the  early-deposited  rocks 
would  be  essentially  granitic  in  composition,  and  non- 

*  Amer.  Jour.  Sci.,  1865,  vol.  zl.,  p.  49;  also  Chem.  and  Geol.  Essays, 
p.  122. 


178 


THE  ORIGIN  OF  CRYSTALLINE  SOCKS. 


[V. 


\('i-  ■•  t, 


magnesian,  until  the  introduction  of  magnesia  into  its 
waters  from  an  exterior  source. 

The  pectolitic  silicates  themselves,  which,  in  the  cavities 
of  exotic  basic  rocks,  are  deposited  in  crystalline  forms, 
would,  if  set  free  in  a  sea  deprived  of  magnesian  salts,  be 
readily  decomposed  by  the  carbonic  acid  every  where  present, 
with  separation  of  free  silica  and  carbonate  of  lime.  From 
this  would  be  formed  the  first  deposits  of  limestone,  which 
make  their  appearance  in  the  old  gneissic  rocks  and 
become  mingled  with  magnesian  carbonate  and  silicates 
from  tiie  introduction  of  magnesian  salts  into  the  waters. 
The  comparative  instability  of  the  lime-silicate  is  seen 
when  wolhistonite  is  compared  with  the  corresponding 
silicates,  pyroxene  and  enstatite.  It  is  possible,  notwith- 
standing the  absence  of  magnesian  species  from  zeolitic 
secretions,  that,  under  certain  conditions,  small  portions 
of  magnesian  silicate  mny  liave  been  included  in  the  early 
crciiitic  deposits,  but  the  rarity  of  such  magnesian  silicates 
in  these,  and  their  abundance  in  parts  of  the  later  Lauren- 
tian  and  in  younger  deposits,  point  to  a  new  source  of 
the  magnesian  element,  namely,  the  extrusion  of  portions 
of  the  underlying  plutonic  mass,  and  its  sub-aerial  decay. 

It  would  be  instructive  to  consider  in  this  relation  the 
gradual  removal  of  a  large  proi)ortion  of  silica  from  the 
primary  plutonic  stratum  in  the  forms  of  orthoclase,  albite, 
and  quartz,  and  the  consequent  partial  exhaustion  of  por- 
tions of  this  underlying  mass,  so  that  its  succ  eding 
secretions  should  consist  'chiefly  of  less  silicic  silicates, 
such  as  labradorite  and  an  .'esite,  without  quartz,  as  in  the 
Norian  series. 

§  120.  The  conditions  of  this  first  exoplutonic  action 
cannot  be  fully  understood  until  Ave  have  settled  the  ques- 
tion of  the  permanence  of  continental  and  oceanic  areas, 
and  the  exter'  of  the  early  crenitic  rocks  which  constitute 
the  fundamental  granites  and  the  granitoid  gneisses. 
Whether  these  are  spread,  with  their  vast  thickness,  alike 
underneath  the  great  areas  of  tne  paleozoic  series  and  our 


<♦ 


▼.] 


THE  CRENITIC   HYPOTHESIS. 


173 


)ur 


modern  oceanic  basins, — in  brief,  whether  or  not  they  are 
universal,  as  supposed  by  Werner,  is  a  question  wliich 
cannot  here  be  discussed.  There  is,  however,  nothing  in- 
compatible with  what  we  know  of  the  chemistry  of  the 
early  rocks  and  the  early  ocean  in  the  supposition  that 
they  were  universal,  since  there  is  apparently  no  evidence 
that  the  products  of  sub-aerial  decay  of  exposed  rocks  in- 
tervened in  their  production.  Such  a  condition  of  things 
was,  however,  necessarily  self-limited;  the  progressive 
diminution  in  volume  of  the  primary  plutonic  stratum 
from  the  constant  removal  of  portions  of  it  in  a  state  of 
solution,  and  the  weight  of  the  superincumbent  accumu- 
lated granitic  and  gneissic  material,  could  not  fail  to 
result  in  widely  spread  and  repeated  corrugations  and 
foldings  of  the  overlying  mass,  the  effects  of  which  are 
seen  in  the  universally  wrinkled  and  frequently  vertical 
attitude  of  the  oldest  gneissic  rocks.  Such  a  process,  like 
the  similar  though  less  considerable  movements  in  later 
times,  would  probably  be  attended  v/ith  outflows,  in  the 
form  of  fissure-eruptions,  of  the  underlying  basic  stratum, 
which,  in  accordance  wich  our  hypothesis,  was  permeated 
with  water  under  conditions  of  temperature  and  pressure 
that  must  have  given  to  it  a  partial  liquidity.  Such  a 
process  of  collapse  and  corrugation  of  the  crenitic  deposits, 
attended  with  extravasation  of  the  underlying  plutonic 
stratum,  wou^d  doubtless  be  often  repeated  in  these  early 
periods,  resulting  in  frequfint  stratigraphical  discordances, 
which  are,  however,  in  all  cases  to  be  looked  upon  as  local 
accidents,  and  not  as  wide-spread  catastrophes.  Hence 
the  appearance,  from  time  to  time,  of  oxoplutonic  masses, 
with  upliftings  and  depressions  of  the  crenitic  rocks,  which 
caused  the  exposure  of  both  alike  to  the  action  of  the 
atmosphere. 

§  121.  The  consequent  sub-aerial  decay  of  these  two 
types  henceforth  introduced  new  factors  into  the  rock- 
forming  processes  of  the  time,  anJ  :^ade  the  beginning  of 
what  Werner  called  the  Transition  period.     The  decompo- 


\^ 


fS  'M 


t'  :'  ■ 


'lii 


'  I 


M^iij^ 


maadi 


180 


I'  \  ■    ■   - 

THE   ORIGIN   OF   CRYSTALLINE  ROCKS. 


[V. 


sition  of  these,  under  the  influence  of  a  moist  atmosphere 
holding  carbonic  acid,  resulted  in  the  more  or  less  com- 
plete removal  of  the  alkali  from  the  feldspars  of  crenitic 
rocks,  and  their  conversion  into  kaolin,  while  the  corre- 
sponding changes  in  the  basic  exoplutonic  rocks  were  still 
more  noteworthy.  These  rocks,  while  containing  feld- 
spars, consisted  in  large  part  of  silicates  of  lime  and  mag- 
nesia, presumably  pyroxene  and  chrysolite,  which,  as  we 
are  aware,  yield  tc  the  action  of  the  atmosphere  the  whole 
of  their  lime  and  magnesia.  These,  in  the  form  of  car- 
bonates, passed  into  soluiioD,  together  with  a  large  propor- 
tion of  silica,  leaving  beli.'ud  the  remaining  portion, 
together  with  iron-oxyd  and  the  kaolin  from  the  feldspars. 
The  carbonates  of  alkalies,  of  lime,  and  of  magnesia,  re- 
sulting from  the  sub-aerial  decay  of  the  exposed  exoplu- 
tonic and  the  crenitic  rocks  alike,  were  carried  to  the  sea, 
there  to  play  an  important  part.  Besides  the  direct  influx 
of  carbonate  of  lime  into  the  waters  of  that  time,  it  is 
evident  that  both  the  alkaline  and  the  magnesian  bicar- 
bonates  would  react  upon  the  calcium-chlorid  of  the 
primeval  sea,  with  the  production  of  a  farther  amount  of 
lime-carbonate,  and  the  generation  of  alkaline  and  mag- 
nesian chlorids.  In  this  way,  the  sea  becoming  magne- 
sian, a  new  order  of  things  was  established.  Henceforth, 
the  pectolitic  matters  brought  up  fruui  the  primary  layer 
would  at  once  react  upon  the  dissolved  magnesian  salts, 
and  the  production  of  such  compounds  as  chondrodii-e, 
chrysolite,  serpentine,  and  talc  would  commence.  No 
one  who  has  studied  the  mode  of  occurrence  of  these 
silicp'eo  in  the  upper  part  of  the  Laurontian  series,  where 
serpentine  not  only  forms  layers,  but  frequent  concretions 
like  flints,  often  around  nuclei  of  white  pyroxene,  can  fail 
to  recognize  the  process  which  then  came  into  play,  result- 
ing later  in  the  production  of  abundance  of  pyroxene, 
amphibole,  and  enstatite,  and  apparently  reaching  its  cul- 
mination in  the  vast  amount  of  magnesian  silicates  found 
in  the  deposits  of  the  II:;ronian  age. 


1 


v.] 


THE  CRENITIC   HYPOTHESIS. 


181 


§  122.  The  solutions  of  simple  silicates'  of  alkalies, 
which  by  heat  had  deposited  their  excess  of  silica  in  the 
form  of  quartz,  as  in  the  case  of  the  soluble  matter  from 
glass,  probably  gave  rise  by  their  reaction  with  magnesian 
solutions  to  the  basic  protoxyd-silicates,  like  chondrodite, 
chrysolite,  serpentine,  and  pyroxene.  That  we  have  no 
anhydrous  quadrisilicates  corresponding  to  apophyllite 
and  okenite  is  apparently  due  to  the  fact  that  such  sili- 
cates, in  contact  with  water  at  elevated  temperatures, 
break  up  into  anhydrous  bisilicates  and  quartz ;  as  is  seen 
in  the  artificial  association  of  pyroxene  and  quartz  in  the 
experiments  of  Daubrde,  and  the  frequent  occurrence  of 
admixtures  of  the  two  in  beds  ;among  the  ancient  gneissic 
rocks.  A  noticeable  fact  in  the  history  of  the  surbasic 
silicates  of  magnesia  and  related  protoxyd-bases,  men- 
tioned above,  is  their  frequent  association  with  non-sili- 
cated  oxyds.  Examples  of  this  familiar  to  mineralogists 
are  the  occurrence  of  aggregates  of  chondrodite  and 
magnetite ;  of  chromite,  picotite,  ilmenite,  and  corundum, 
with  chrysolite  and  serpentine ;  and  of  frankli.iite  and 
zuicite  with  tephroite  and  willemite.  These  collocations 
are  probably  connected  with  the  solvent  power  of  solu- 
tions of  alkaline  silicates,  already  insisted  upon  (§  89), 
and  also  with  the  dissociation  of  silicate  of  alumina  in 
heated  alkaline  solutions,  noticed  by  H.  Deville  (§  98). 

The  separation,  by  the  alternate  action  of  decaying 
organic  matters  and  of  atmospheric  oxygen,  of  iron-oxyd, 
whica  readily  passes  from  a  soluble  ferrous  to  an  insolu- 
ble ferric  condition.,  and  conversely,  has  probably  played 
an  important  part  in  the  formation  of  deposits  of  iron- 
Dxyds,  wliich  are  much  more  general  in  their  asso- 
ciations than  corundum,  or  the  compounds  of  chromic, 
titanic,  aluminic,  manganic,  and  zincic  oxyds  mentioned 
above,  to  which  we  have  assigned  a  very  different  origin. 
It  will  remain  for  the  mineralogist  to  determine  what  de- 
posits of  magnetite  and  of  hematite  are  to  be  ascribed  to 
the  one  and  what  to  the  otlier  origin. 


J 


*    n 


182 


THE  ORIGIN  OP  CRYSTALLINE  BOCKS. 


[V. 


§  123.  We  have  seen,  among  the  secretions  of  basic 
rocks,  lime-alumina  silicates,  like  epidote  and  prehnite,  in 
which  the  ratio  of  the  protoxyd-bases  to  alumina,  instead 
of  being  1  :  3,  as  in  the  feldspars  and  the  zeolites,  is  1^  : 
3  or  even  2  :  3.  Although,  probably  on  account  of  their 
solubility  and  their  instability,  we  do  not  know  of  any 
natural  silicates  with  a  still  larger  proportion  of  lime  to 
the  alumina,  we  have  indirect  evidence  of  their  former 
existence  in  solution,  in  the  frequent  occurrence  of  double 
silicates  of  magnesia  and  alumina,  in  which  the  oxygen- 
ratio  of  R,  al,  instead  of  being  1  :  3,  >s  in  the  feldspars, 
or  2  :  3,  as  in  prehnite,  becomes  3  :  3  and  even  6  :  3,  as 
seen  in  the  magnesian  micas  and  in  the  chlorites.  Such 
silicates,  often  with  epidote,  abound  in  the  rocks  of 
Huronian  age. 

This  process  by  which,  through  the  intervention  of  sili- 
cated  secretions  from  the  substratum,  the  magnesian  salts 
are  removed  from  the  sea-water,  is,  as  we  have  shown,  the 
reverse  of  that  which  takes  place  through  the  action  of 
the  carbonates  from  the  sub-aerial  decay  of  silicated  rocks 
precipitating  lime-salts  and  giving  rise  to  magnesian 
wafers,  if  not  over  oceanic  areas,  at  least  in  inland  basins 
of  greater  or  less  extent.  Alternations  of  this  kir  1  must 
have  been  frequent  in  geological  history,  and  we  have 
evidence  of  a  widespread  phenomenon  of  this  kind  fol- 
lowing the  Huronian  age,  when  in  seas  from  which  mag- 
nesian salts  were  apparently  for  the  most  part  excluded, 
were  deposited  the  gneisses  and  mica-schists  of  the  Mont- 
alban  series.  These,  in  very  many  places,  are  found 
resting  directly,  often  in  unconformable  superposition, 
upon  the  older  or  Laurentian  gneisses,  but  elsewhere  upon 
the  Huronian,  showing  the  intervention  of  extensive 
movements  of  elevation  and  subsidence,  and  probably  of 
denudation,  subsequent  to  the  Huronian  time. 

§  124.  The  introduction  on  a  limited  scale,  into  the 
sea-basins  of  the  Montalban  time,  of  magnesian  salts  is 
evident  from  the  occasional  appearance  of  magnesian  sili- 


mus^ 

marl 

cess 

a  pi 

dimii 

* 

Amerl 


mf. 


of 


h 


v.] 


THE  CllENITIC   HYPOTHESIS. 


183 


cates  in  the  Montalban  rockf .  The  most  noteworthy  fact 
ill  their  history  is,  however,  the  appearance  in  this  series, 
with  gneisses  which  differ  from  those  of  older  times  in 
being  finer  grained  and  less  granitoid,  of  deposits  contain- 
ing aluminous  silicates  characterized  by  a  diminished  pro- 
portion of  protoxyd-bases.  Such  as  these  are  the  beds  of 
quartzose  schists  holding  non-magnesian  micas  and  the 
simple  silicates,  andalusite,  fibrolite,  and  cyanite.  It  has 
already  been  mentioned  that  in  the  formation  of  these 
rocks  the  more  or  less  completely  decomposed  feldspar 
from  the  sub-aerial  decay  of  older  crenitic  rocks  may  have 
been  brought  into  the  areas  of  deposition.  Either  such 
clays,  still  retaining  a  portion  of  alkali  from  undecayed 
feldspar,  or  else  admixtures  of  kaolin  with  the  elements 
of  a  feldspar  or  a  zeolite  might,  as  has  been  suggested, 
yield,  by  diagenesis,  muscovite  and  quartz,  with  one  of 
the  simple  aluminous  silicates  just  named.  That  a  pro- 
cess of  sub-aerial  decay  was  in  progress  in  the  Montalban 
time  is  shown  by  the  presence  in  the  mica-schists  of  this 
series,  at  several  localities  in  Saxony  and  elsewhere,  as 
described  by  Sauer  and  subsequently  noticed  by  the 
present  writer,  of  "boulders  of  decay,"  having  all  the 
appearance  of  those  formed  during  the  atmospheric  decay 
of  the  older  gneisses.*  The  intervention  in  the  deposits 
of  that  period  of  somewhat  basic  zeolitic  minerals,  is 
shown  by  the  presence  in  the  younger  gneissic  series  of 
Germany  of  large  masses  of  so-called  dichroite-gneiss  or 
iolite-gneiss,  and  the  occasional  occurrence  of  iolite  in  the 
younger  or  Montalban  gneisses  of  New  England. 

§  125.  The  predominance  of  micaci^ous  schists  of  the 
muscovitic  type  in  the  upper  portions  of  the  Montalban, 
marks  the  growing  change  in  the  conditions  of  the  pr-  - 
cess  which  gave  rise  to  the  indigenous  crystalline  rocks ; 
a  process  continued  with  many  modifications,  and  with 
diminished  energy,  through  the  subsequent  period  of  the 

*  Sauer,  in  1879,  Zeltschrift  f.  d.  ges.  Naturwiss,  Band  lii;  also  Hunt, 
Amer.  Jour.  Sci.,  1883,  vol.  xxvi.,  p.  197,  and  Essay  X.,  §  80. 


i 


ill 


I       ! 


i     J 


m 


hi,''\ 


i  i 


m 


rv  Jl'il 


184 


THE  OlilGlN   OF  CRYSTALLINE  ROCKS. 


rv. 


Taconian.  This  was  marked  by  the  deposit  of  quartzites, 
limestones,  and  argillites,  and  also  by  the  intercalation  of 
schistose  beds  characterized  by  an  abundance  of  damour- 
ite  or  relat3d  micaceous  minerals,  as  well  as  by  the  pres- 
ence of  matters  apparently  feldspathic,  which  seldom  take 
upon  themselves  the  characteis  of  well  defined  species, 
though  found  transformed  by  sub-aerial  decay  into  a  form 
of  kaolin,  and  in  some  instances  apparently  assuming  the 
state  of  an  imperfect  gneiss.  These  Taconian  schists, 
which  require  careful  chemical  and  microscopic  study, 
also  include  serpentine,  talc,  pyroxene,  epidote,  and  gar- 
net. The  appearance  in  jjaleozoic  argillites  of  crystals  of 
rutile,  of  tourmaline,  and  of  staurolite,  indicates  a  later 
stage  of  that  condition  of  things  which  marked  the  cre- 
nitic  process  in  pre-paleozoic  times,  and  made  possible  the 
formation  of  the  vast  series  of  Primitive  and  Transi- 
tion crystalline  schists  which  we  have  sought  to  include 
under  the  names  of  Laurentian,  Norian,  Arvonian,  Huro- 
nian,  Montalban,  and  Taconian — designating  in  their 
order  the  upward  succession  of  these  great  groups  from 
the  fundamental  granitoid  gneisses  (here  included  in  the 
Laurentian)  to  the  dawn  of  paleozoic  time.  The  Arvo- 
nian or  petrosilex  group  intervenes  between  the  Lauren- 
tian and  the  Huronian.  The  peculiar  characters  of  the 
Norian,  and  its  localization  to  some  few  limited  areas  in 
Europe  and  North  America,  make  it  difficult  for  us,  as 
yet,  to  define  its  precise  relations  to  the  Arvonian.  The 
Norian,  however,  like  the  Arvonian,  probably  occupies  a 
horizon  between  Laurentian  and  Huronian.  Much  time 
may  pass,  and  many  stratigraphical  studies  must  be  made, 
before  the  precise  relations  of  the  Huronian  and  the  suc- 
ceeding Montalban  can  be  defined.  It  seems  probable,  in 
the  present  state  of  our  knowledge,  that  the  Montalban 
series,  though  of  great  thickness,  was,  in  manj'  cases,  de- 
posited over  areas  where  the  Huronian  had  never  been 
laid  down.  Notwithstanding  the  great  geographical  ex- 
tent and  the  importance  of  these  two  series,  neither  can 


doi 


call 
in 

«l 

ti 
ScleJ 


^a-^' 


v.] 


THE  chenitic  hypothesis. 


185 


claim  that  universality  which  apparently  belonged  to  the 
primitive  granitic  stratum;  a  universality  soon  interrupted 
by  the  uplifting  of  portions  of  dry  land,  an  event  which 
preceded  Huronian  time. 

§  126.  That  the  production  of  large  quantities  of  simi- 
lar pectolitic  silicates,  in  regions  remote  from  exotic  rocks, 
was  continued  from  the  pre-Cambrian  to  far  niore  recent 
times  is  evident,  from  the  presence  of  a  considerable  de- 
posit of  serpentine  among  the  horizontal  Silurian  dolo- 
mites of  Syracuise,  New  York,  of  which  the  writer  hag 
elsewhere  recorded  the  history,*  and  also  from  the  well 
known  beds  of  sepiolite  found  with  opal  in  the  tertiary 
dolomites  of  the  Paris  basin.f  The  recent  amorphous  zeo- 
litic  deposits  in  tertiary  sandstone  in  Switzerland  (§  94), 
and  the  compounds  referred  to  on  page  164,  should  not 
be  forgotten  in  this  connection.  . 

Whether  the  silicates  brought  from  below  by  crenitic 
action  were  directly  separated  as  feldspars,  rs  crystalline 
zeolites,  or  as  gelatinous  precipitates  to  be  subsequently 
changed  by  diagenesis  into  crystalline  hydrous  or  anhy- 
drous species,  are  questions  for  farther  dij.cussion.  The 
range  of  temperature  through  which  we  have  noted  uhe 
crystallization  of  chabazite,  and  the  association  of  ortho- 
clase  by  contemporaneous  or  subsequent  crystallization 
with  hydrous  species  like  zeolites  and  chlorite,  lead  us  to 
conclude  that  for  the  hydrous  and  anhydrous  aluminous 
double  silicates  alike,  a  considerable  range  of  temperature 
is  permissible.  In  any  case,  we  lind  notliing  in  the  condi- 
tions of  the  formation  of  zeolitic  minerals  in  the  past,  any 
more  than  in  modern  times,  incompatible  with  the  exist- 
ence of  organic  life. 

§  127.  The  phenomena  of  exoplutonic  action,  or  so- 
called  vulcanicity,  though  relegated  to  a  secondary  place 
in  the  crenitic  hypothesis,  are  yet,  as  we  have  said,  of 


•  See  farther,  Essay  X.,  §§  27-34. 
t  Hunt,  on  the  Dulomites  of  the  Paris  Basm,  1860. 
Science,  xxix.,  p.  284. 


Amer.  Jour. 


hi 


186 


THE  ORIGIN   OF  CRYSTALLINE  ROCKS. 


tv. 


great  importance  and  significance,  and  are  by  no  means 
simple.  They  were,  according  to  our  hypothesis,  confined 
in  early  times  to  fissure-eruptions  of  the  underlying  plu- 
tonic  stratum.  This,  although  in  the  course  of  ages  it 
has  suffered  a  gradual  change  from  the  ceaseless  crenitio 
action,  which  has  removed  from  it  the  elements  of  the  va- 
rious series  of  crystalline  rocks,  including  the  primitive 
granitic  and  gneissic  series,  probably  still  retains  in  the 
lower  portions  somewhat  of  its  original  constitution. 

A  second  phase  in  the  history  of  exopluton.ic  rocks,  al- 
ready foreseen  by  the  Huttonians,  here  presents  itself  for 
our  consideration.  The  more  deeply  buried  portions  of 
the  primitive  crenitic  deposit  must  themselves  have  been 
brought  within  the  influence  of  the  central  heat,  and,  per- 
meated as  they  were  by  water,  would  have  suffered  a 
softei  ing  which  permitted  them,  as  a  result  of  subsequent 
movements  of  the  crust,  to  appear  again  at  the  earth's 
surface  as  exoplutonic  or  exotic  rocks  of  the  trachytic  or 
granitic  type. 

We  can  hardly  suppose  the  displacement,  either  of  the 
plutonic  stratum,  or  of  the  early  granitic  deposits,  to  have 
been  attended  with  the  evolution  of  permanent  gases, 
such  as  attend  modern  volcanic  eruptions  and  are  to  be 
ascribed  to  the  action  of  subterranean  heat  on  more  re- 
cent deposits,  including  carbonates,  suli^hates,  chlorids, 
and  organic  matters.  Such  materials,  when  mingled  with 
silicious  and  argillaceous  sediments,  and  brought  by  local 
accumulation  and  depression  within  the  heated  zone, 
would  give  rise  to  the  various  gases  which  characterize 
the  volcanic  eruptions  of  recent  periods,  in  which,  how- 
ever, the  materials  of  the  underlying  plutonic  and  crenitic 
layers  also  apparently  intervene.  V   '    , 

By  thus  ascribing  a  threefold  origin  to  the  products  of 
exoplutonic  action,  it  becomes  possible  to  classify  and 
harmonize  the  apparently  discordant  phenomena  of  erup- 
tive rocks.  While  the  typical  basalts  and  related  basic 
rocks  would  be  derived  from  the  primary  plutonic  or  ig- 


!♦ 


/?\j, 


u 


v.] 


THE  CKENITIO   HYPOTHESIS. 


187 


neous  stratum,  and  the  trachytic  and  granitic  rocks  from 
the  earlier  crenitic  deposits,  the  more  fusible  portions  of 
the  hater  Transition  and  Secondary  strata  may  liave  fur- 
nished tlieir  contingent,  not  only  of  gases  and  vapors,  but 
of  lavas  and  volcanic  dust. 

§  128.  The  history  of  the  origin  of  crystalline  roclfs  is 
the  history  of  the  origin  of  the  mineral  species  which 
compose  them.  The  crystalline  masses  are  essentially 
made  up  of  a  few  groups  of  species.  Various  feldspars, 
and  occasional  zeolites,  some  of  which  apparently  occur 
as  integral  parts  of  roc)  :s  chiefly  feldspathic,  form  a  great 
central  group.  On  one  side  of  these  are  the  aluminous 
double  silicates,  represented  by  basic  species  like  garnet, 
epidote,  magnesian  micas  and  chlorites,  all  with  an  excess 
of  protoxyd-bases ;  while  on  the  other  hand  are  the  alu- 
minous double  silicates  of  the  muscovitic  and  pinitic 
groups,  in  which  the  diminished  proportion  of  the  pro- 
toxyd-bases prepares  the  way  to  the  associated  simple 
aluminous  silicates,  pyrophyllite,  andalusite,  cyanite,  etc. 
To  these  groups  must  be  added  the  non-aluminous  sili- 
cates, including  amiDhibole,  pyroxene,  enstatite,  and  chrys- 
olite, and  the  hydrous  magnesian  species,  serpentine  and 
talc.  Besides  these  are  free  silica,  generally  as  quartz, 
free  oxyds,  including  the  spinel  and  corundum  groups, 
which,  together  with  the  carbonates,  make  up  the  essen- 
tial parts  of  the  crystalline  rocks. 

§  129.  Rock-masses,  and  the  mineral  species  which 
compose  them,  present  variations  in  time,  as  we  find  in 
tracing  the  history  of  the  great  successive  groups  of  crys- 
talline strata ;  and  they  moreover  show  local  changes,  as 
seen  in  different  parts  of  their  distribution  in  the  same 
geologic.il  group.  As  regards  the  causes  of  these  varia- 
tions, very  much  remains  to  be  discovered  by  the  patient 
collection  and  recording  of  facts  concerning  the  associa- 
tions of  mineral  species,  their  artificial  production,  and 
their  transformations  under  the  influences  of  fire  and 
water,  and  of  solutions  of  potassic,  sodic,  calcareous,  and 


I  ! 


188 


THE  ORIGIN  OF  CRYSTALLINE  HOCKS. 


[V. 


wm 


magnesian  salts.  The  instability  of  silicated  compounds 
of  igneous  origin  in  the  presence  of  water  and  watery- 
solutions,  so  widely  diffused  through  nature,  is  the  war- 
rant for  a  general  aqueous  hypothesis;  while,  on  the  other 
hand,  the  derivation  of  stable  nuneral  species,  under  such 
influences,  from  matters  of  igneous  origin  justifies  ua  in 
assuming  for  these  species  an  igneous  starting-point. 

Igneous  fusion  destroys  the  mineral  species  of  the  crys- 
talline stratified  rocks,  and  brings  them  back  as  nearly  as 
possible  to  the  primary  undifferentiated  material.  P'ire  is 
the  great  destroyer  and  disorganizer  of  mineral  as  well 
as  of  organic  matter.  Subterranean  heat  in  our  time, 
acting  upon  buried  aqueous  sediments,  destroys  carbo- 
nates, sulphates,  and  chlorids,  with  the  evolution  of  acidic 
gases  and  the  generation  of  basic  silicates,  and  thus 
repeats  in  miniature  the  conditions  of  the  ante-nep- 
tunian  chaos,  with  its  surrounding  acidic  atmosphere. 
On  the  other  hand,  each  mass  of  cooling  igneous  rock  in 
contact  with  water  begins  anew  the  formative  process. 
The  hydrated  amorphous  i)roduct,  palagonite,  is,  if  we 
may  be  allowed  the  expression,  a  soH  of  silicated  proto- 
plasm, and  by  its  differentiation  yields  to  the  solvent 
action  of  water  the  crystalline  silicates  which  are  the  con- 
stituent elements  of  the  crenitic  rocks,  leaving,  at  the 
same  time,  a  more  basic  residuum,  abounding  in  magnesia 
and  iron-oxyd,  and  soluble,  not  by  crenitic,  but  by  sub- 
aerial  action.  Palagonite,  or  some  amorphous  matter  re- 
sembling it,  probably  marks  a  stage  in  the  sub-aqueous 
transformation  of  all  igneous  rocks,  though  only  under 
special  conditions  does  this  unstable,  hydrous  substance 
form  appreciable  masses.  In  all  cases,  igneous  matter,  of 
primary  or  of  secondary  origin,  serves  as  the  point  of  de- 
parture. 

According  to  the  proposed  hypothesis,  which  derives 
rocks  of  the  granitic  type,  composed  essentially  of  quartz 
and  feldspars,  by  aqueous  secretion  from  a  primary  igne- 
ous and  quartzless  mass,  it  would  follow  that  the  highly 


v.] 


THE  CUKNITIC    IIVl'OTHESIS. 


189 


basic  compound,  assumed  by  Bunsen  to  represent  the  typi- 
cal pyroxenic  or  basaltic  rock  (§  24),  would  be  the  above 
mentioned  insoluble  residuum;  and  that  less  basic  varie- 
ties of  similar  rocks  would  correspond  to  portions  of  the 
same  primary  plutonic  mass,  less  completely  exhausted  by 
lixiviation,  or  modified  by  partial  separation  through 
crystallization  and  eliquation,  as  will  be  explained  in 
Essay  VI.,  and  consequently  approacliing  in  composition 
to  admixtures  of  the  basaltic  and  granitic  types,  as  main- 
tained on  other  grounds  by  Bunsen  himself. 

§  130.  The  principles  which  have  been  enumerated  in 
the  preceding  pages,  will,  it  is  believed,  lead  the  way, 
not  only  to  a  natural  system  of  mineralogy,  but  to  a  natu- 
ral system  of  classification  of  crystalline  rocks,  considered 
with  regard  alike  to  their  chemical  composition,  their 
genesis,  and  their  geological  succession.  A  valid  hypothe- 
sis for  the  crystalline  rocks  must  seek  to  connect  all  the 
known  facts  of  their  history,  by  alleging  a  true  and  suf- 
ficient cause  for  the  production  of  their  various  constitu- 
ent mineral  species.  Such  a  hypothesis  will  violate  no 
established  principles  in  chemistry  or  in  physics,  but  will 
show  itself  to  be  in  accord  with  them  all,  and  will  com- 
mend itself  to  the  acceptance  of  those  who  take  the  pains 
to  understand  it. 

The  crenitic  hypothesis  set  forth  in  these  pages  is  the 
result  of  many  years  of  patient  study  applied  to  the  elu- 
cidation of  a  great  problem ;  and  as  such  is  offered  to 
chemists  and  mineralogists  as  a  first  attempt  at  a  rational 
explanation  of  the  fundamental  questions  presented  by 
the  history  of  the  crystalline  rocks  of  the  earth's  crust. 


I 


m: 


VI. 

THE  GEXETIC  HISTORY  OP  CRTSTALLINE  ROCKS. 

Thii  Kwiay  wai  prpsentod  to  tho  Roynl  Society  of  Canada  at  Iti  meeting  In  Ottawa, 
May,  18H0,  iind  will  appear  In  ItH  TransactionH,  vol.  Iv.,  with  the  above  title.  In  May, 
188S,  there  wan  read  before  the  Banie  iociety  a  paper  In  which  the  phenomena  of 
(tratltlcatlon  In  endogenous  velnntoMfH  and  In  eruptud  rocks  were  discussed  In  rela- 
tion to'tbecrenlttc  process,  and  to  the  hypothesis  of  ellquatlon.  Of  this  paper,  which 
was  published  only  In  abstract  In  the  Canadian  Ilecord  of  Science,  under  the  title  of 
The  Geognosy  of  Crystalline  Uooks,  the  present  essay  It  but  an  extensloii  and  a 
development. 

I. 

§  1.  In  a  preceeding  essay  on  The  Origin  of  Crystalline 
Rocks,  we  have  considered  at  length  the  different  views 
hitherto  maintained  as  to  the  mode  of  their  production, 
and  have  set  forth  what  we  have  called  the  crenitic  hy- 
pothesis. It  is  proposed  in  the  following  pages  to  ex- 
amine still  farther  the  new  hypothesis  in  some  of  its 
aspects,  to  show  how  far  the  conception  of  a  single  con- 
solidated igneous  mass  under  the  combined  action  of  water 
and  heat  may  be  made  to  explain  satisfactorily  the  various 
facts  in  the  history  of  the  earth's  crystalline  crust,  and 
thus  to  reconcile  many  of  the  contradictions  which  still 
divide  the  geological  world  as  to  the  relations  of  stratified 
and  massive  crystalline  rocks.  Hence  the  title  of  the 
present  essay. 

Of  the  great  divisions  adopted  by  the  Wernerian  school 
in  geology,  those  of  Primary  and  Secondary  correspond 
respectively  to  Original  and  Derived  rocks,  and  were  sup- 
posed to  represent  earlier  and  later  periods  in  geologic 
time ;  the  name  of  Transition  being  applied  to  the  rocks 
of  an  intermediate  period,  believed  to  mark  the  passage 
from  the  conditions  of  the  primary  to  those  of  the  second- 
ary age.     The  name  of  Tertiary  given  to  the  rocks  of  a 

190 


n.l  GENETIC   ITrSTOTlY  OF  CRYflTALLINR  ROCKS.       191 


still  lator  ago  and,  marking?  a  subsequent  period  in  the 
process  of  derivation,  needs  no  explaiuition.  Hy  tlio  geol- 
ogists of  the  Huttonian  school  tlio  rocks  called  primary 
or  original  by  the  Werncrians  were  imagined  to  bo  in 
many,  if  not  in  all  cases,  secondary  or  derivcil  rocks,  the 
materials  of  which,  got  from  the  disintegration  of  pre- 
existing masses,  had  been  arranged  by  water,  and  subse- 
quently transformed  by  combined  mechanical  and  chemi- 
cal agencies  into  their  present  crystalline  condition;  in 
accordance  with  which  hypothesis  they  have  been  called 
Metamorphic  rocks.  By  rejecting,  as  their  master  Mutton 
had  done,  all  "incjuiry  into  the  first  origin  of  things,"  or 
"the  commencement  or  termination  of  the  present  order," 
and  by  teaching  that  tha  rocks  called  by  Wernerians 
primary  and  transition,  were  for  the  most  part,  if  not 
wholly,  metamorphosed  portions  of  derived  rocks  which, 
themselves,  in  their  prolongation  into  other  regions,  could 
be  recognized  as  secondary  or  as  tertiary  strata,  the 
Huttonians  have  sought  to  destroy  the  chronological 
value  of  the  Wernerian  terminology.  With  the  abandon- 
ment of  the  Huttonian  or  so-called  metamorphic  doctrine, 
now  shown  to  be  false,  so  far  at  least  as  regards  the  sec- 
ondary or  tertiary  age  of  crystalline  stratified  rocks,  we 
are  naturally  led  back  to  the  nomenclature  of  Werner 
and  his  school,  which  should  be  equally  acceptable  to 
endoplutonists  and  to  neptunists,  whether  the  latter  adopt 
the  chaotic  hypothesis  of  Werner,  the  modified  or  ther- 
mochaotic  hypothesis  set  forth  by  De  la  Beche  and  Dau- 
brde,  or  the  crenitic  hypothesis  more  recently  maintained 
by  the  present  writer  in  the  essay  just  cited. 

§  2.  The  term  "crystalline  rocks  "  is  conventionally  used 
in  geology  to  designate  those  original  aggregates  of  which 
crystalline  silicates  make  an  essential  part.  Such  silicates 
may  however  be  associated  in  these  aggregates  with  quartz, 
or  with  oxyds  like  magnetite,  with  carbonates,  as  in  lime- 
stones and  dolomite,  and  even  with  phosphates,  as  apatite, 
or  with  sulphates,  as  karstenite  and  gypsu.n.    By  a  certain 


192 


THE  GENETIC   HISTORY 


[VI. 


license  the  term  may  also  be  extended  to  masses  of  defi- 
nite hydrous  silicates,  such  as  serpentine  and  pinite,  which 
are  in  great  part  amorphous  and  colloidal,  and  also  to  un- 
crystalline  silicates,  often  hydrated,  and  of  indefinite  com- 
position, such  as  palagonite,  tachylite,  pitchstone,  and 
obsidian.  The  silicates  having  tlie  composition  of  serpen- 
tine and  of  pinite  assume,  in  some  cases,  proper  crystalline 
forms ;  palagonite  is  by  heat  readily  changed  in  large  part 
into  a  crystalline  zeolite ;  while  glassy  silicates,  such  as 
obsidian,  by  devitrification  are  in  like  manner  resolved 
more  or  less  completely  into  crystalline  species.  Hence 
rock-masses,  including  or  even  made  up  of  these  various 
un  crystalline  materials,  may  all  be  regarded  as  inchoately 
crystalline,  and  for  geognostical  purposes  may  be  conve- 
niently classed  with  the  crystalline  rocks  into  which  they 
graduaie. 

§  3.  When  stratified  masses  of  quartz,  calcite,  dolomite, 
and  karstenite  are  found  among  contemporaneous  crystal- 
line silicated  rocks,  they  generally  enclose  indigenous 
crystalline  silicates,  which  give  them  a  title  to  be  regai-ded 
as  parts  of  the  accompanying  crystalline  series.  The 
mineral  species  just  named  have,  however,  in  other  cases 
be.?ome  aggregated  in  crystalline  rock-masses  in  times  and 
under  conditions  which  did  not  permit  the  genesis  of  such 
species  as  feldspars,  micas,  amphibole,  and  pyroxene,  which 
are  the  most  characteristic  silicates  of  the  crystalline  rocks. 
Hence  we  find  beds  of  crystalline  quartz,  limestone,  dolo- 
mite, karstenite,  and  gypsum  interstratified  with  uncrys- 
talline  rocks  of  detrital  origin,  and  of  secondary  or 
tertiary  age.  It  is  worthy  of  note,  however,  that  the 
conditions  for  the  production  of  certain  mineral  silicates 
have  continued  ii'  later  ages,  as  is  shown  by  the  frequent 
formation  of  zeolitic,  pectolitic,  and  other  crystalline  sili- 
cates in  younger  and  uncrystalline  rocks,  and  even  down 
to  our  own  time,  and,  moreover,  by  the  occurrence  among 
uncrystalline  sediments  of  later  geological  periods,  of 
deposits  of  serpentine,  sepiolite,   and   glauconite.      The 


J  (1 


mi 


OF  CRYSTALLINE   ROCKS. 


193 


history  of  both  zeolitic  and  pcctolitic  silicates  as  formed 
by  secretions  in  basic  rocks,  and  as  generated  in  deep-sea 
ooze,  and  in  the  channels  of  thermal  waters,  has  been  dis- 
cussed at  some  length  in  the  preceding  essay,  but  there 
are  facts  in  relation  to  the  other  silicates  just  mentioned 
which  are  of  such  importance  in  connection  with  the 
origin  of  crystalline  rocks  as  to  merit  consideration  in  this 
place. 

§  4,  Two  examples  of  crystalline  silicates  related  to 
zeolites  in  composition,  which  are  found  injecting  organic 
remains  in  paleozoic  limestones,  have  been  observed  by  Sir 
J.  W.  Dawson,  and  were  farther  described  and  analyzed 
by  the  present  writer  in  1871.  The  first  of  these  is 
from  a  Silurian  limestone  which  is  found  near  Woodstock, 
in  the  province  of  New  Brunswick,  and  consists  almost 
wholly  of  comminuted  organic  remains,  including  frag- 
ments of  tiilobites,  gasteropods,  brachiopods,  and  joints 
and  plates  of  small  encrinites,  the  whole  cemented  by  cal- 
cite.  The  pores  of  the  crinoidal  remains  are  tilled  by  a 
peculiar  silicate,  seen  in  sections  or  on  surfaces  etched  by 
an  acid.  Surfaces  thus  treated  show  a  congeries  of  curved, 
branching,  and  anastomosing  cylindrical  rods  of  the  inject- 
ing mineral,  sometimes  forming  a  complete  network,  and 
exhibiting  under  a  microscope  coralloidal  forms,  with  a 
white,  frost-like,  crystalline  aspect  resembling  the  variety 
of  aragonite  known  as  jlos  ferri.  The  same  crystalline 
mineral,  as  observed  by  Dawson,  occasionally  fills  the 
interstices  between  the  larger  fragments  of  organic  forms 
in  the  limestone,  and,  as  he  observes,  "was  evidently 
deposited  before  the  calcite  which  cements  the  whole 
mass." 

§  5.  The  limestone  in  question  is  nearly  pure,  contain- 
ing very  little  magnesia  or  iron-oxyd,  and  leaves,  after  the 
action  of  cold  dilute  chlorhydric  acid,  five  or  six  hun- 
dredths of  insoluble  residue  which  is  the  mineral  in  ques- 
tion with  about  one  fourth  its  weight  of  silicious  sand. 
The  silicate  is  of  a  pale  grayish-green  color  when  seen  in 


i 


if  1 


f '  "^ 


m' 


194 


THE  GENETIC   HISTOKY 


tvi. 


mass,  and,  losing  water,  becomes  bright  reddisli-bro-wn  by 
calcination.  It  is  partially  decomposed  by  strong  heated 
chlorhydric  acid,  and  completely  by  hot  sulphuric  acid, 
which  dissolves  alumina,  ferrous  oxyd,  magnesia,  and  small 
portions  of  alkalies,  leaving  flocculent  silica,  which  is 
readil}'  separated  by  a  solution  of  carbonate  of  soda  from 
the  accompanying  quartz-grains.  Thus  analyzed,  the 
mineral,  which  under  a  lens  appeared,  wholly  crystalline 
and  homogeneous,  save  the  accompanying  quartz,  yielded 
silica  38.93,  alumina  28.88,  ferrous  oxyd  18.86,  magnesia 
4.25,  potash  1.G9,  soda  0.48,  water  6.91.  The  atomic  ratio  of 
this  for  ])rotoxyds,  alumina,  silica,  and  water  is  very  nearly 
1:2:3:1,  whi  h,  abstracting  the  water,  is  that  of  zoisite ; 
the  hydrous  silicate  jollyte  being  1:2:3:2.  I  have  given 
to  this  crystalline  silicate,  which  is  of  curious  interest 
alike  for  its  composition  and  the  mode  of  its  occurrence, 
the  name  of  hamelite,  for  the  Rev.  Dr.  Hamel,  rector  of 
La\al  University,  Quebec* 

S  6.  The  second  silicate  above  referred  to  is  not  unlike 
hamelite  in  its  characters  and  manner  of  occurrence, 
though  differing  somewhat  in  atomic  ratios.  It  was 
found  in  a  mass  of  fossiliferous  limestone  said  to  be  from 
a  locality  in  the  island  of  Anglesey,  and  including,  "  be- 
sides a  small  coral-like  body  referred  to  the  genus  Verti- 
cillopora,  joints  and  plates  of  crinoids,  small  spiral 
gasteropod  shells,  with  fragments  of  brachiopods,  and  a 
sponge-like  organism  with  square  meshes."  All  of  these 
organic  forms  are  more  or  less  penetrated  with  a  greenish 
silicate,  which  fills  the  cavities  of  the  gasteropods,  the 
central  canal  of  the  crinoids,  and  the  pores  of  the  Verti- 
cillopora.  It  has  also  replaced,  or  filled,  the  spongy  fibres, 
and  injected  the  minute  cells  of  some  of  the  crinoidal  frag- 
ments, though  many  of  these  are  solid  throughout,  in  which 
respect  the  specimen  differs  from  that  from  New  Bruns- 

*  Amer.  Jour.  Science,  1871,  i.,  379;  also  J.  W.  Dawson.  The  Dawn 
of  Life,  pp.  120-123,  with  figure  of  a  portion  of  infiltrated  crinoid  on  p. 
103. 


U 


VI.] 


OF  CRYSTALLINE  ROCKS. 


195 


wick  described  above,  where  the  infiltration  of  the  cri- 
noidal  remains  is  much  more  complete  and  perfect.  Sir 
J.  W.  Dawson,  to  whom  we  owe  these  observations,  sup- 
poses that  in  both  cases  the  infiltration  took  place  while 
the  remains  were  still  recent. 

§  7.  Decalcified  surfaces  of  this  limestone  from  An- 
glesea  show  similar  appearances  to  those  presented  by  the 
New  Brunswick  specimen,  and  the  casts  of  the  gasteropo- 
dous  shells,  two  millimetres  in  length,  are  in  some  cases 
perfect.  The  limestone  is  nearly  pure  with  the  exception 
of  a  little  fine  yellow  ochreous  matter  which  is  insoluble 
in  the  dilute  chlorhydric  acid,  and  remains  suspended  in 
the  solution,  but  is  easily  separated  by  washing  from  the 
pale  grayish-green  silicate.  This  equals  about  three  hun- 
dredths of  the  weight  of  the  limestone.  When  ignited 
in  the  air  it  assumes  a  bright  fawn  color,  and  under  a  lens 
contrasts  strongly  with  the  colorless  grains  of  quartz  with 
which  it  is  mixed.  Its  chemical  characters  were  like 
those  of  hamelite,  and  analyzed  in  the  same  manner  it 
gave,  after  deducting  21.0  per  cent  of  insoluble  sand,  the 
following  composition :  Silica  35.72,  alumina  22.26,  ferrous 
oxyd  21.42,  magnesia  6.98,  potash  1.49,  soda  0.67,  water 
11.46  =  100.00.*  This  gives  for  protoxyds  alumina,  silica, 
and  water  very  nearly  the  atomic  ratios  3:4:7:4;  but 
we  are  not  sure  of  its  homogeneous  character.  A  silicate 
very  like  this  in  aspect  and  mode  of  occurrence  has  been 
found  in  a  band  of  fossiliferous  limestone  near  the  base  of 
the  coal-measures  in  southern  Ohio,  but  has  not  yet  been 
chemically  examined. 

§  8.  In  connection  with  these  minerals  should  be  no- 
ticed a  greenish  fibrous  asbestiform  silicate,  elsewhere 
described  by  the  writer,  which  occurs  in  veins  traversing 
the  anthracite  and  the  carbonaceous  shales  of  the  coal- 
measures  at  Portsmouth,  Rhode  Island,  either  without 
admixture,  or  mingled  with  pyrites,  or  penetrating  white 
quartz,  and  also  coating  the  fragments  of  the  crumbling 

*  Amer,  Jour.  Science,  1871,  ii.,  57. 


THE  GEI^ETIC  HISTORY 


lyi. 


!  (   H     » 


«  '",   1 


^^®  ,.  •    „  hvdvou3  silicate  of  ata- 

litic  minerals  or  e^yy^  fprrous  oxyd,  n^ve  gi>  , 

^  u  p— ,rt'  o^«-  ^2^^^ 

"'"TtotScatf  lil^e  -r"*'"l;5:'^:'t  named  occur. 

T^:x^*a*  — s  i>et^-r  s;t« 

often  forms  beds  w-.h  but  ^^^^^  ^hat  glauc 

»-'^  ^T^ilXTt  si«.S  oi  fora»in«e.a  a.^^^« 
„ite  is  met  witli  W™8  eologioal  times,  a 

"^"■^  ."rim;  —  in  recent  foramm  -  „  v^  .^ 
°°r::  Tride  o^  its  occ-ence  -  t^„  ^^,^^,,„ 
ous  sea&.         ,  ^r +Vift  aluminous  douDie»^  compo- 

^'"""f™* t  *-t  -  '^^"ir'  atd'biir  -e»t-"y 
forms  from  '""";.„  variable ;  and.wni 
.itiono£glaucomte>s^eiy       ^^^  .^^^       a,  '* -"^^^^i,. 


tlrl 


OF   CRYSTALLINE  ROCKS. 


197 


Indeed,  a  so-called  green-sand  from  the  calcaire  grossier, 
according  to  Berthier,  is  rather  a  highly  ferrous  serpentine, 
containing,  silica  40.0,  ferrous  oxyd  24.7,  magnesia  16.6, 
lime  3.3,  alumina  1.7,  water  12.6  =  98.9.* 

§  11.  These  variations  show  that  the  material  in  ques- 
tion is  a  mixture,  and  render  it  difficult  to  fix  its  real 
constitution.  According  to  the  multiplied  analyses  of 
Haushofer,  the  iron  present  in  glauconite  is  for  tlie  most 
part  in  the  ferric  condition,  the  ferrous  oxyd  in  various 
examples  ranging  from  three  to  seven  hundredths.  The 
formula  proposed  by  him  represents  glauconite  as  contain- 
ing 6.3  of  ferrous  oxyd,  8.3  of  potash,  anJ  9.6  of  water, 
with  22.7  of  ferric  oxyd  and  3.6  of  alumina,  giving  for 
the  atomic  ratios  of  protoxyds,  sesquioxyds,  silica,  and 
water,  1  :  3  :  9  :  3.f  The  very  variable  quantity  of  alu- 
mina found  in  glaucjnites  may,  however,  well  be  owing 
to  a  zeolitic  admixture ;  and,  if  we  hazard  the  conjecture 
that  the  large  proportion  of  ferric  oxyd  therein  is  due  to  a 
partial  oxydation  of  what  was  originally  a  ferro-potassic 
silicate,  we  should  have  for  its  composition  before  peroxy- 
dation  (deducting  the  alumina  as  a  zeolite  with  the  above 
atomic  ratios,  like  faujasite)  a  silicate  with  the  ratios 
for  protoxyds,  silica,  and  water,  of  3  :  9  :  3 ;  corresponding 
to  sepiolite,  and  to  an  unknown  pectolitic  silicate  inter- 
mediate between  pectolite  and  apophyllite,  which  may  be 
supposed  to  have  given  rise  alike  to  talc,  to  sepiolite,  and 
to  glauconite.  The  variable  amounts  of  magnesia  in 
glauconite  itself  would  thus  be  due  to  an  admixture  of 
sepiolite.  The  reaction  of  such  a  soluble  pectolitic  com- 
pound, having  a  lime-potash  base  like  apophyllite,  with 
the  dissolved  magnesian  salts  in  sea-water  would  generate 
a  magnesian  silicate  having  the  ratio  of  talc  and  sepiolite 
(which  latter  forms  beds  in  tertiary  sediments),  and  with 
ferrous  solutions  by  a  similar  double  decomposition  might 

*  Beudant,  Traits  de  Mineralogie,  ii.,  178.  See  also  Report  Geol. 
Survey  of  Canada,  1866,  p.  231. 

t  Cited  in  Dana's  System  of  Mineralogy,  5th  ed.,  p.  462. 


198 


THE  GENETIC  HISTORY 


[VL 


*,'4,i 


<  .    1 


•I 'I 


yield  a  ferro-potassic  silicate  like  glaucoiiite.  It  is  well 
known  that  un^er  proper  conditions  decaying  organic 
matters  acting  upon  sediments  containing  ferric  oxyd 
reduce  this  and  give  rise  to  such  solutions,  in  which  fer- 
rous carbonate  is  often  associated  with  a  proportion  of  an 
organic  acid.  Such  a  solution  and  redeposition  in  the 
forms  of  sideriteand  pyrite  goes  on  in  sedimentary  depos- 
its through  this  agency  (Essay  VII.,  §  35),  and  this  would 
permit  the  conditions  necessary  to  produce  glauconite 
with  the  pectolitic  silicate,  which  in  the  absence  of  the 
iron-solution  would  generate  sepiolite  by  reaction  with 
magnesian  salts. 

§  12.  The  variations  in  the  composition  of  glauconite- 
like  minerals,  and  the  existence  in  silicates  similar  to  it  in 
their  mode  of  occurrence  of  more  or  less  alumina  and 
magnesia,  probably  corresponding,  as  suggested  above,  to 
admixtures  of  zeolite  and  sepiolite,  are  farther  illustrated 
by  the  following  analyses  by  the  writer.  I.  is  a  typical 
glauconite  from  the  green-sand  beds  of  the  cretaceous 
series  in  New  Jersey ;  II.  a  glauconite,  remarkable  for  its 
fine  green  color,  which  forms  layers  in  the  Cambrian 
(Potsdam)  sandstone  at  Red  Bird,  Minnesota ;  III.  a  simi- 
lar material  found  in  a  Cambrian  sandstone  on  the  island 
of  Orleans,  near  Quebec.  The  results,  after  deducting 
silicious  sand,  are  calculated  for  one  hundred  parts,  and 
the  whole  of  the  iron  is  represented  as  ferrous.* 


t 

I. 

11. 

III. 

SUica    .    .    . 

50.70 

46.58 

50.'i 

Ferrous  oxyd 

.    22.50 

20.61 

8.6 

Magnesia  .     . 

.      2.16 

1.27 

3.7 

Lime     .    .    . 

.      1.11 

2.49 

— 

Alumina   .    . 

,      8.03 

11.45 

19.8 

Potash  .    .    . 

.      5.80 

6.96 

8.2 

Soda     .    .    . 

.76 

.98 

.5 

Water 

8.95 

9.66 

8.5 

100.00 


100.00 


100.00 


r 


*  Geology  of  Canada  in  1863,  p.  486;  also  Rep.  Geol.  Survey  of  Can- 
ada 1863-^9,  p.  232. 


VI.] 


OF   CRYSTALLINE   ROCKS. 


199 


§  13.  The  crenitic  hypothfpis  advanced  by  the  present 
writer  in  the  preceding  essay  to  exphiin  the  aqueous  ori- 
gin of  the  mineral  species  which  make  up  alike  the  gran- 
ites and  the  crystalline  stratified  rocks,  supposes  that  from 
an  early  period  watery  solutions  analogous  to  those  which 
in  later  times  have  given  rise  to  zeolitic  and  pectolitic 
minerals,  played  an  important  part  in  the  chemistry  of 
the  earth.  The  double  silicates  of  alumina  and  lime  or 
alkalies  then  dissolved,  are  conceived  to  have  been  the 
source  not  only  of  the  feldspars  and  the  zeolites,  but  of 
epidote,  garnet,  muscovitic  micas,  and  tourmalines,  and, 
b}'^  their  reactions  with  magnesian  and  ferrous  solutions, 
of  the  chlorites  and  the  highly  protobasic  micas.  At  the 
same  time  the  dissolved  protoxyd-silicates  not  onl}^  gave 
rise  to  species  like  pectolite  and  apophyllite,  but,  by  similar 
reactions,  to  pyroxene,  amphibole,  chrysolite,  serpentine, 
talc,  sepiolite,  and  glauconite,  arid,  by  decomposition 
through  carbonic  dioxyd,  to  carbonate  of  lime.  In  both 
cases  the  solutions,  like  those  in  later  zeolite-bearing  rocks, 
carried  free  silica  and  iron-oxyd,  which  were  deposited  as 
quartz  and  magnetite  and  hematite.  These  silicated  solu- 
tions, according  to  this  hypothesis,  resulted  primarily  from 
the  action  of  permeating  waters  at  high  temperatures,  ■ 
under  pressure,  upon  the  universal  stratum  of  basic  plu- 
tonic  rock;  and  secondarily  from  their  action  upon  the  dis- 
placed portions  of  this  stratum,  which,  in  a  more  or  less 
modified  form,  have  appeared  in  all  geological  periods  as 
erupted  basic  rocks.  These,  in  their  secreted  minerals, 
show  us  in  later  times,  and  on  a  smaller  scale,  the  process 
which  in  previous  ages  built  up  great  masses  of  indige- 
nous and  endogenous  crystalline  rocks.  To  what  extent 
these  deposits,  more  or  less  concretionary  in  their  origin 
and  their  arrangement,  were  laid  down  horizontally,  and 
to  what  extent  in  inclined  or  vertical  layers,  as  in  many 
veinstones,  is  a  question  which  will  be  discussed  farther 
on  in  this  essay. 

§  14.   Having  thus  briefly  restated  the  crenitic  hypoth- 


200 


THE  GENETIC  HISTOET 


CVI. 


.li    ! 


esis  so  far  as  it  is  related  to  the  classes  of  rocks  already 
noticed,  we  have  to  consider  in  the  next  place  the  ques- 
tion of  exoplutonic  or  eruptive  rocks.  It  will  be  remem- 
bered that  the  existence  of  such  rocks,  having  an  igneous 
origin,  was  not  admitted  by  the  "NVernerians,  who  conceived 
not  only  all  endogenous  rocks,  but  also  all  exotic  masses, 
except  modern  lavas,  to  be  of  aqueous  origin.  By  the 
earlier  Huttonians,  wlio  understood  better  the  geological 
importance  of  the  eruptive  rocks,  these  were  looked  upon 
as  results  of  the  fusion  of  deeply  buried  detrital  materials, 
themselves  derived  from  similar  rocks  of  higher  antiquity. 
The  hypothesis  of  great  chemical  changes  to  explain  the 
genesis  of  many  crystalline  rocks  from  such  material  by 
what  was  comprehensively  designated  as  "metamorphism," 
and  generally  involved  a  supposed  metasomatic  process, 
was  devised  at  a  later  day  by  the  disciples  of  Hutton. 
Haidinger  and  Bischof  may  be  looked  upon  as  the  origina- 
tors of  that  view  of  metasomatic  changes  in  rock-masses 
by  aqueous  action  which,  from  its  supposed  analogy  with 
the  phenomena  giving  rise  to  what  are  called  pseudomor- 
phous  shapes  or  pseudo-crystals,  has  been  infelicitously  de- 
scribed as  "  jjseudomorphism  on  a  broad  scale."  * 

§  15.  The  stratiform  arrangement,  which  extends  to  the 
intimate  structure  of  crystalline  masses  such  as  gneisses 
and  mica-schists,  is  by  endoplutonists  supposed  to  be  due 
to  movements  in  an  imperfectly  homogeneous  semi-fluid 
material  dependent  on  unequal  cooling  and  the  rotation 
of  the  globe,  and  to  be  analogous  to  the  banded  structure 
apparent  in  lavas  and  furnace-slags.  In  the  exoplutonic 
hypothesis,  on  the  contrary,  it  is  maintained  that  the  in- 
ternal movements  in  such  material,  when  forced  outwards 
and  upwards  chrough  the  earth's  superficial  crust,  have 
given  to  the  masses  that  laminated  structure  and  that 
arrangement  of  the  constituent  elements  which,  alike  by 
Wernerians  and  Huttonians,  are  regarded  as  evidences  of 
deposition  from  water.     This  latter  or  exoplutonic  view 

*  Ante,  page  100. 


VI.] 


OP  CRYSTALLINE  ROCKS. 


201 


was  clearly  expressed  by  Poulett  Scrope,  sixty  years  since, 
in  his  "New  Theory  of  the  Earth,"  published  in  1825 
(^ante,  page  81),  wherein  he  imagines  the  granite  to  have 
formed  the  original  surface  of  the  globe,  and  supposes 
that  movements  in  extruded  portions  of  the  mass  com- 
pressed beneath  overlying  sediments  gave  to  it  the 
gneissic  structure.  He  insists  upon  the  friction  of  its 
elements  "as  they  were  urged  forward  in  the  direction  of 
their  plane  surfaces  towards  the  orifice  of  protrusion,  along 
the  eximnding  granite  beneath,  the  laminae  being  elon- 
gated and  the  crystals  forced  to  arrange  themselves  in  the 
direction  of  the  movement."  This  view  was  adopted, 
though  without  acknowledgment,  by  J.  D.  Dana  in  1843, 
when  he  argued  that  the  schistose  structure  of  gneiss  and 
mica-schist  is  not  a  satisfactory  evidence  of  sedimentary 
origin,  since  erupted  rocks  may  assume  a  laminated  arrange- 
ment.* 

§  16.  The  same  notion  has  continued  to  find  favor 
among  geologists  of  the  plutonist  school  up  to  the  present 
time.  Poulett  Scrope  himself,  in  rewriting  his  famous 
treatise  on  Volcanoes,  after  a  lapse  of  thirty-seven  years, 
restates  his  argument  with  great  precision.  He  therein 
supposes  that  the  primitive  material  of  the  globe,  so  far  as 
known,  was  an  aggregate  consisting  essentially  of  feldspar, 
quartz,  and  mica,  in  a  crystalline  or  granular  condition. 
This  material,  which  was  impregnated  with  water  and 
highly  heated,  possessed  a  certain  plasticity,  and  when 
extruded  by  pressure  took  upon  itself  a  stratiform  struc- 
ture, being  "bodily  forced  up  the  axial  fissure  of  disloca- 
tion in  crumpled  zigzag  folds  or  upright  walls  of  vertical 
laminated  rock."  To  show  to  what  extent  this  view  had 
met  the  approval  of  other  geologists,  Scrope  farther  ob- 
served, "  The  late  Mr.  Sharpe  and  Mr.  D:  vwin,  as  is  well 

*  Scrope,  Considerations  on  Volcanoes,  etc.,  1825,  p.  22.  See  also 
J.  D.  i)ana.  On  the  Analogies  Between  Modem  Igneous  Rocks  and  the 
so-called  Primary  Formations,  1843;  Amer.  Jour.  Science,  1843,  xlv., 
104-129  ;  and  ante,  pages  89,  90. 


I 


202 


THE  GENETIC  HISTORY 


tvi. 


f'^ 


■I : 


known,  concurred  in  the  opinion  here  given,  that  at  least 
as  respects  the  oldest  or  fundamental  gneiss,  its  foliated 
structure  is  duo  not  to  original  sedimentary  deposition, 
but  to  the  movement  of  the  particles  under  great  pressure 
while  the  nuiss  was  in  a  condition  of  imperfect  igneous 
fluidity.  Prof.  Naumann  has  still  more  recently  advo- 
cated the  same  view,  which  is,  however,  resisted  by  Lyell, 
Murchison,  Geikie,  and  others."  * 

§  17.  The  same  view  has  very  recently  been  brought 
forward  by  Joh.  Lehmann,  who  maintains,  with  Scrope, 
that  the  schistose  structure  in  crystalline  rocks  is  no  evi- 
dence of  aqueous  deposition,  but  is  imposed  upon  them 
by  the  process  of  extrusion.  The  Saxon  granulites, 
according  to  Lehmann,  were  intrusive  masses  which  con- 
solidated among  sedimentary  strata  far  below  the  surface, 
and,  being  afterwards  forced  up  by  great  pressure,  took 
upon  themselves  a  banded  schistose  arrangement,  the  adja- 
cent strata,  more  or  less  impregnated  by  the  granulitic  ma- 
terial, appearing  as  micaceous  gneisses  and  mica-schists.f 
This  whole  g-anulitic  series  of  Saxony  may  be  described 
as  made  up  of  fine-grained  binary  gneisses  (granulites), 
passing  into  micaceous  gneisses  and  mica-schists,  and  has 
been  by  the  present  writer  elsewhere  referred  to  the 
younger  gneissic  or  Montalban  series  of  crystalline  rocks.J 

§  18.  An  example  of  the  resuscitation  of  the  views  of 
Poulett  Scrope  in  North  America  is  found  in  a  recent  note 
by  Prof.  H.  Carvill  Lewis  on  the  crystalline  schists  of  east- 
ern Pennsylvania.  A  belt  of  these  which  crosses  the 
Schuylkill  near  Philadelphia,  long  ago  described  by  H.  D. 
Kogers,  and  since  by  the  present  writer,§  includes  a  band 
of  granitoid  gneiss  succeeded  by  micaceous  gneisses  and 

*  Scrope,  on  Volcanoes,  2d  ed.,  1862,  as  revised  in  1872,  pp.  300-305. 

t  Joh.  Lehmann;  Untersuchungen  iiber  die  Enstehung  dov  Altkrys- 
tallinen  Schiefergesteine,  1884.  Not  having  boon  able  to  consult  this 
work,  I  am  indebted  for  a  notice  of  its  argument  to  a  review  in  the  Amer. 
Jour,  Science,  xxviii.,  p.  39. 

t  See  Essay  X.,  §§  71),  80. 

§  See  Himt,  Azoic  liocks,  pp.  10-15  and  200;  also  Essay  X.,  §  18, 


t» 


VI.] 


OF  CRYSTALLINE  ROCKS. 


203 


micaceous  schists,  often  giirnetiferous,  comprising  a  layer  of 
serpentine  witli  steatite  and  dioritic  rocks,  the  whole  rep- 
resenting both  the  okler  and  the  younger  gneissic  series 
so  well  known  in  eastern  North  America  as  Laurentian 
and  Montalban.  The  rocks  in  tiiis  belt,  notwithstanding 
their  stratiform  character,  are,  in  the  opinion  of  Lewis, 
"of  purely  eruptive  origin,  consisting  of  syenites,  acid 
gabbros,  trap-granulites,  and  other  igneous  rocks,  often 
highly  metamorphosed.  It  is  the  outer  peripheral  portions 
of  this  zone  to  which  attention  is  here  directed.  While 
the  rocks  are  massive  in  the  centre,  this  outer  portion  has 
been  enormously  compressed,  folded,  and  faulted,  with 
the  result  of  producing  a  tough  banded  porphyritic  fluxion- 
gneiss."  Lewis  supposes  "a  recrystallization  of  the  old 
material  under  the  influence  of  pressure-fluxion,"  by  which 
he  conceives  the  feldspar  to  have  been  recrystallized.  "  In 
similar  manner  the  biotite  has  been  made  out  of  the  old 
hornblende,  garnets  have  been  developed,  and  the  quartz 
has  been  granulated  and  optically  distorted  by  the  pres- 
sure." In  another  example  mentioned  by  him,  a  belt  of 
sphene-bearing  amphibolite  schist,  described  as  included 
unconformably  in  the  mica-schists  of  Philadelphia,  is  sup- 
posed by  Lewis  to  be  "  a  highly  metamorphosed  intrusive 
dike  of  Lower  Silurian  age.  The  original  augite  or  diallage 
has  been  completely  converted  into  fibrous  hornblende, 
and  the  influence  of  pressure  is  shown  in  the  perfectly 
laminated  character  of  the  schist,  in  the  close  foldings 
produced,  and  in  the  minute  structure  of  the  rock."  "  The 
chemical  changes  and  interchanges  of  elements  which 
might  result  from  a  loosening  of  molecular  combinations 
under  extreme  pressure,"  and  their  subsequent  re-arrange- 
ment to  form  new  compounds,  suggest  to  Lewis  great 
possibilities  in  the  so-called  "  mechanical  metamorphisra  " 
now  advocated  by  some  to  replace  the  discredited  dogma 
of  chemical  metamorphism,  which  has  hitherto  played  such 
an  important  part  among  a  school  of  geologists.* 

*  H.  C.  Lewis,  Proc.  British  Association,  in  Nature,  Oct.  8, 1885,  p.  560. 


V:: 


> ';! 


«  f 


204 


THE  GENETIC   HISTOIIY 


tvi. 


§  10.  Tims,  wliile  the  ancient  Wernerians  maintained 
the  direct  dopoHition  of  granite  from  aqueous  solutions  in 
a  chaotic  ocean,  the  plutonists,  from  Ponlett  Scrope  in 
1825  to  Darwin,  Naunuuin,  Lclnnann,  and  I^ewis,  assert 
the  igneous  origin  not  only  of  granites  but  of  gneisses  and 
micaceous  and  amphibolic  schists,  and  the  followers  of 
the  Iluttonian  or  metamorphic  school  hold  an  untenable 
and  an  illogical  position  between  the  two,  —  deriving  the 
materials  of  both  of  these  rocks  from  a  primary  granitic 
mass,  whose  origin  is  unaccounted  for,  and  whose  sup- 
posed transforniiitions  chemistry  cannot  explain. 

§  20.  It  remains  to  notice,  in  connection  with  the  nep- 
tunian,  the  plutonic,  and  the  metamorphic  hypotheses, 
regarding  the  sources  and  the  geognostic  relations  of  the 
crystalline  rocks,  a  view  which  has  been  proposed  to  ex- 
phain  the  attitude  of  certain  apparently  exotic  masses: 
wliich  is  that  their  present  position  is  due  neither  to  de- 
position from  solution  nor  to  intrusion  in  a  fluid  or  plastic 
condition,  but  to  local  movements  which  have  permitted 
portions  of  rigid  rock  to  displace  and  even  penetrate  softer 
and  more  yielding  materials  in  their  vicinity.  Examples 
of  this  are  described  by  Stapff  as  seen  in  the  St.  G(.Miard 
tunnel  in  the  Alps,  where  great  masses  of  serpentine  'nve 
been  caused  to  traverse  adjacent  schistose  strata ;  the 
solid  condition  of  the  intruding  rock  being  made  evident 
by  the  accompanying  breccia,  consisting  of  its  fragments.* 
There  is  reason  to  believe  that  such  instances  are  not  un- 
common, and  that  in  many  cases  the  phenomenon  of  in- 
trusion is  due  to  the  superior  hardness  of  the  intruding 
rock,  broken  beds  or  masses  of  which  are  forced  through 
softer  strata;  the  conditions  being  the  reverse  of  those 
which  attend  plutonic  or  volcanic  injections.  The  notion 
that  rocks  when  in  a  solid  condition  may  be  intruded 
aniong  others,  is  found  in  the  pages  of  more  than  one 
writer  on  geological  questions,  but,  so  far  as  the  writer  is 
aware,  is  for  the  first  time  clearly  and  satisfactorily  de- 

*  See  farther,  Essay  X.,  §§  128-130,  wliere  details  and  references  are  given. 


VJ.] 


OF  CUYSTALLLNE  HOCKS. 


205 


fined  in  tlio  description  of  Rtapff,  whioli  ia  an  important 
concoptiun  gu';ied  fur  the  student  of  gongnosy. 

§  21.  The  endoplutonists.  us  wo  have  .seen,  have  sought 
to  explain  tlio  laminated  structure  of  certain  crystalline 
rocks,  not,  like  the  exoplutonists,  by  the  pressure  attend- 
ant on  extrusion,  but  by  movements  in  an  imperfectly 
fluid  material  in  which,  during  refrigeration,  a  separation 
of  solid  matters  and  a  process  of  elii^uation  were  going  on. 
The  possible  production  in  this  manner  alike  of  unstrati- 
fied  and  stratiform  crystalline  rocks  from  an  igneous  mass 
is  ingeniously  set  forth  by  Thomas  Macfarlane  in  his 
studies  of  the  geology  of  Lake  Superior.*  He  notes  first 
the  occurrence  of  fragments  of  denser  and  more  basic 
hornblendic  aggregates  enclosed  in  lighter  and  less  basic 
granitoid  masses,  and,  from  these  facts,  and  the  composi- 
tion and  specific  gravity  of  granitic  veins  penetrating  tlio 
masses,  conjectures  that  these  various  products  represent 
different  stages  in  crystallization  from  a  primitive  magma, 
the  first  separated  ])ortions  from  whicli  were  more  basic 
and  the  later  more  silicious. 

If  this  took  place  when  the  mass  was  undisturbed,  a 
granitoid  rock  would  be  formed ;  but  if  while  it  was  in 
motion,  "hornblendic  and  micaceous  schists  and  gneisses 
were  most  probably  the  results  of  this  process,  and  the 
strike  of  these  would  indicate  the  direction  of  the  current 
at  the  time  of  their  formation."  The  material  thus  sepa- 
rated, notwithstanding  its  greater  specific  gravity,  is  sup- 
posed to  have  formed  at  the  surface  of  the  molten  mass,  as 
a  result  of  cooling;  but  in  Macfarlane's  view  "there 
arrived  a  time  when,  from  some  cause  or  other,  these  first 
rocks  were  rent  or  broken  up  and  the  crevices  or  interstices 
became  filled  with  the  still  fluid  and  more  silicious  material 
which  existed  beneath  them.  This  gradually  solidified  in 
the  cracks,  or  in  the  spaces  surrounding  the  fragments, 
and  the  whole  became  again  a  consolidated  crust  above  a 

*  Geological  Features  of  Lake  Superior,  Canadian  Naturalist,  May, 
1867. 


fill  *, 


li 


t}'t "' 

m 


nr 


0^ 


.}■?. 


206 


THE   GENETIC   HISTOIIY 


[VI. 


fluid  mass  of  still  more  silicioiis  material,"  which  by  sub- 
sequent movements  would  again  be  intruded  in  the  form 
ci  veins  in  the  broken  crust.  This  restatement  of  the 
hypothesis  of  the  solidification  of  a  molten  globe  from 
above  downwards,  already  taught  by  Naumann,*  serves  to 
show  how  the  endoplutonist  school  explains  the  origin 
alike  of  massive  and  of  stratiform  crystalline  rocks,  and 
may  be  compared  with  the  detailed  statement  of  the  exo- 
plutonist  view  as  set  forth  by  Poulett  Scrope. 

§  22.  The  broad  distinction  sometimes  drawn  between 
stratified  crystalline  rocks  as  of  indigenous  and  aqueous 
origin,  and  unstratified  rocks  as  intruded  or  exotic  masses 
of  igneous  origin,  thus  finds  no  place  in  the  hypotheses  of 
the  plutonic  schools,  according  to  both  of  which  these  two 
classes  of  rocks  have  come  directly  from  a  primitive  fused 
mass,  which  was  either  simple  or  had  become  complex 
through  differentiation.  The  Huttonian  school  also, 
which  teaches  that  eruptive  rocks,  in  many  if  not  in  all 
cases,  were  originally  sediments  which,  as  a  result  of  pro- 
found alteration,  have  lost  their  bedded  structure,  arrives 
by  a  different  route  to  a  conclusion  not  unlike  chat  of  the 
plutonists  ;  namely,  that  the  differences  between  stratified 
and  unstratified  rocks  are  due  solely  to  superinduced 
structure  and  geognostic  relations.  Those  who,  for  the 
most  part  unfamiliar  with  any  other  view,  acquiesce  in 
the  metamorphic  hypothesis  of  Hutton  and  his  followers, 
now  so  popular  with  a  school  of  writers  on  geology,  are 
scarcely  prepared,  without  farther  study,  to  criticise  intel- 
ligently either  the  plutonic  or  the  crenitic  hypothesis  of 
l^e  origin  of  crystalline  rocks.  The  latter,  as  set  forth  in 
the  preceding  essay,  and  concisely  resumed  on  page  199  of 
the  present,  supposes  that  the  source  of  all  crystalline 
rocks  is  to  be  sought  in  a  previously  solidified  primary  plu- 
tonic material.  The  elements  of  these  rocks  have  been  de- 
rived in  part  indirectly,  by  aqueous  solution,  and  in  part 
directly  from  this  original  mass,  more  or  less  profoundly 

*  See  ante,  page  85, 


VI.] 


OF  CRYSTALLINE  KOCKS. 


207 


II 


altered  alike  by  previous  aqueous  action  and  by  differen- 
tiation through  ciystallization  and  eliquation.  By  this 
hypothesis,  as  we  have  elsewhere  attempted  to  show,  we 
may  hope  to  lay  the  foundation  of  a  rational  geogeny 
and  geognosy. 

§  23.  We  have  already,  in  the  preceding  essay,  consid- 
ered at  some  length  the  views  of  those  who,  noting  the 
existence  of  predominant  types  of  crystalline  rocks,  have 
sought  to  explain  their  origin  by  supposing  the  presence 
beneath  the  earth's  solid  crust  of  two  distinct  layers  of 
molten  rock :  an  upper,  lighter,  and  more  viscous  silicious 
or  so-called  acidic  stratum,  the  material  of  trachj^tes,  gran- 
ites, and  gneiss ;  and  a  lower,  heavier,  and  more  fluid  basic 
layer,  the  source  of  doleritic  and  basaltic  rocks, —  a  view 
which  was  put  forth  by  John  Phillips,  defended  by  Bun- 
sen,  and  elaborated  and  more  definitely  formulated  by 
Durocher.  To  this  are  opposed  the  modified  view  of  Von 
Waltershausen,  of  a  gradual  passage  downward  in  a  liquid 
mass  from  a  more  acidic  to  a  more  basic  portion,  and  the 
entirely  distinct  view  held  and  defended  by  the  present 
writer  as  the  basis  of  the  crenitic  hypothesis.  According 
to  this  the  plutonic  underworld,  so  far  as  it  intervenes 
directly  in  geologic  phenomena,  is  an  essentially  homoge- 
neous basic  rock,  not  in  a  state  of  simple  and  original 
igneous  fusion,  but  solidified  and  subsequently  impreg- 
nated with  water,  which  communicates  a  certain  plasticity 
to  the  highly  heated  mass,  and,  moreover,  dissolves  and 
removes  therefrom  the  materials  of  the  trachytic  and  gran- 
itic rock,  —  which  are  thus  primarily  of  aqueous  origin. 

§  24.  This  process  implies  secular  changes  in  the  com- 
position of  the  plutonic  stratum,  which  are  mr  reover 
local,  since  the  conditions  of  solution  and  upward  perco- 
lation will  vary  in  different  areas,  and  during  different 
periods  in  the  same  area.  It  involves  also  a  coxT'^spond- 
ing  change  in  the  nature  of  the  materials  dissolved,  so 
that  differences  greater  or  less  are  to  be  looked  for  in  the 
composition  alike   of  eruptive  plutonic   and   of   crenitic 


1*1 


f 


i  1 


t- 


♦  ■ii 


'1   1 


208 


THE  GENETIC  HISTORY 


[VI. 


are  compf^^'e^^'     i^e  evi  composition  or  xi 

independent  of  aqueous     Uon  i        ^^^^^^  ,^,evyation  of 
Plutonic  mass  did  «.«\^47^^i,,,,,,ed  by  him  m  lus  le- 
?)uroclier,  and  was  m  1857^^^    petrology.*     To  this  I 
1  ni.iA  pssav  on  Compaiative  x  ryurocher's  view 

nS     tXn  in  1858,  ^''''"If  *t"  imagined  by  hin. 

S^ t o  st.au  of  -«»»;::, Itr;  a  partial  .y^^ 
c^occasionally  move  o   less.  „  ^^^^  „,e  to  the 

nation  ami  ^l""*'","'  -L  and  basic  cvystalline  locl-s.t 
principal  vavisties  of  acid.c  ana  ^,^^„„,,  bj 

^\  25.  This  view  was  sU^i  ™'   J,  .vhich  have  pvo- 
Duvooher,  who  declared    '  Jhe  »•  g  ^  ^         t,^u„ 

duced  the  igneous  rocks  ate  to  ^j  j„^,o„, 

t  hs,  which,  holding  many  »*  ^  ;,u„y„  according  to 
separate  in  solid.tymg  jto  j^tt  ^^.^^^ ,.  _  t,  en-cmn- 
the  circumstances  of  their  son  ^^^^^  than  of  an 

rtan  es  being  ^'^r^'^  fcoVing  »  1^-°  »"* 
nterior  order."  S^lj'^^^^^^'^th  a  tJachytic  porphyry, 
hiffiily  aluminous  phonol.te  wit  ^j^^t  an 

Se'silicious  and  '-'^^^'""^^.tns  would  give  the 
admixture  of  these  »\,<=S,^e,^nd  expresses  the  opm- 
composition  of  a  normal  ttacliyte,  j^^^,    u  the  two 

oTthat  the  rocks  thus  conipa  ed  a^^^.  P  ^^^^  ^^^^^  .„  ,, 
opposite  products  of  an  el.'l"^'^"  ^^^^aon  of  two  oppo- 
Sst  of  the  liquid  mass,  as  in  the  .^  ^^  ^^^^,_,^  .^^^  ^ 

site  alloys,  into  which  a  ™<=*f'f  elicuation  he  conceived 
epa^te"     Tl«'e  rhenome^i    of ^e^u    ^^_^^  ^^^^^  ^,k, 

r:  b^-^rSf-^^e^ibe  eart^mi  in  its  caverns 
td  crev^^t  as  -U  a-*  the  surface^  ^^ 

''"l  26.  The  P--o'^^^''fy  f.  t  lenoniena  due  to  the 
ehUts  .dio  l-y^^  -'^tuing  and  solidifying  points 
erystalluation  and  differ  _^^^^^_,  „,„„,,„«..  ., 

.  Ann»l«  des  Mine.,  ^L,  21.         j,^^^„_,^  „,  1859. 


VI.] 


OF  CRYSTALLINE  ROCKS. 


209 


of  metallic  alloys,  as,  for  example,  the  separation  of  lead 
from  its  silver-bearing  alloy  in  the  Pattinson  process,  and 
tlip  eliquation  of  this  metal  from  its  alloy  with  copper. 
It  was  adopted  by  Macfarlane  in  1867,  in  explanation  of 
the  relations  of  more  or  less  basic  hornblendic  and  gran- 
itic rocks,  already  cited  in  §  21,  and  finds  a  striking  illus- 
tration in  the  late  experiments  of  Fouqu^  and  Michel  Ldvy 
on  the  artificial  production  of  crystalline  mineral  species 
from  fused  vitreous  mixtures.     From  such  a  mixture,  con- 
taining the  elements  of   six   parts  of  chrysolite,  two  of 
pyroxene,  and  six  of  labradorite,  kept  at  a   heat  near 
whiteness  for  forty-eight  hours,  there  separated  crystals  of 
chrysolite,  0.5  millimetre  in  diameter,  together  with  mag- 
netite and  spinel  (picotite) ;  a  vitreous  magma  still  re- 
maining, from  which  crystallized,  at  a  lower  temperature, 
macled  crystals  of  labradorite,  with  pyroxene,  magnetite, 
and  spinel,  as  before.     It  is  apparent  that  with,  a  greater 
lapse  of   time,  and   the  formation   of  larger  crystals  of 
chrysolite,  which  has  a  specific  gravity  of  about  3.4,  these 
would,  under  ':he  influence  of  gravity,  subside,  together 
with  magnetitt  and  spinel,  from  a  fused  glass  holding  the 
elements  of  pyroxene  and  feldspar,  the  r.iore  so  as  the  den- 
sity of  fused  doleritic  and  basaltic  material  is  less  than 
2.8.     From  such  a  slowly  cooling  mixture  the  process  of 
eliquation  would,  under  favorable  conditions,  give  rise  to 
a  highly  chrjoolitic  aggregate  on  the  one  hand  and  to  a 
dolerite  with  little  or  no  chrysolite  on  the  other.     More- 
over, if,  as  is  probable,  there  are  conditions  under  which 
pyroxene  may  be  separated  in  a  similar  manner  from  the 
feldspathic  element,  we  should  have  a  farther  differentia- 
tion, giving  rise  to  heavier  and  highly  pyroxenic  portions 
on  the  one  hand  and  to  lighter  and  more  feldspathic  por- 
tions on  the  other. 

§  27.  The  careful  student  of  crj^stalline  rocks  will 
have  noticed  many  examples  in  nature  of  variations  in 
different  portions  of  eruptive  masses,  which  find  a  ready 
explanation  in  a  process  of  partial  solidification  and  eli- 


210 


THE  GENETIC   HISTORY 


m. 


■■:  :■■% 


(jUiition,  as  suggested  by  Duroclier  and  illustrated  by  the 
experiments  of  Fouqu^  and  Michel  L6vy.  This  is  well 
displayed  in  certain  rocks  intruded  among  the  Ordovician 
strata  of  the  St.  Lawrence  valley,  near  Montreal,  and  form- 
ing the  hills  known  as  llougeniont,  Moutarville,  and 
Mount  Royal.  These,  as  I  have  long  since  described 
then),  are  essentially  doleritic,  but  present  very  great  dif- 
ferences in  the  proportions  of  their  mineralogical  elements 
in  contiguous  parts.  Thus  in  some  portions  of  these 
masses  we  have  a  pyroxene  and  labradorite  rock  in  which 
these  two  elements  are  pretty  equally  distributed,  while 
in  other  portions  the  rock  is  almost  wholly  a  black,  coarsely 
crystalline  pyroxene,  with  but  an  insignificant  piuportion 
of  the  feldspathic  element.  Elsewhere  the  arrangement 
of  these  two  species  gives  rise  to  a  stratiforn  \  structure. 

§  28.  As  described  by  me  in  1863,*  for  Mount  Royal, 
"  mixtures  of  augite  and  feldspar  are  met  with,  constitut- 
ing a  granitoid  dolerite,  in  parts  of  which  the  feldspar  pre- 
dominates, giving  rise  to  a  light  grayish  rock.  Portions 
of  this  chaa'acter  are  sometimes  found  limited  on  either 
side  by  bands  of  nearly  pure  black  pyroxenite,  giving  at 
first  sight  the  aspect  of  stratification.  The  bands  of  these 
two  varieties  are  found  curiously  contorted,  and  .  .  .  seem 
to  have  resulted  from  movements  in  a  heteroge}i80us  pasty 
mass,  which  have  effected  a  partial  blending  of  an  augitic 
magma  with  one  more  feldspathic  in  nature."  In  the 
doleritic  mass  of  Montarville  the  alternation  of  a  coarse- 
grained variety  of  dolerite,  porphyritic  from  the  presence 
of  large  crystals  of  pyroxene,  with  a  finer-grained  and 
whiter  variety  is  noticed,  the  two  "being  arranged  in 
bands  whose  varying  thickness  and  curving  lines  suggest 
the  notion  that  they  have  been  produced  by  the  flow  and 
the  partial  commingling  of  two  fluid  masses."  Of  this 
stratiform  structure  it  was  then  said,  it  seems  to  be  due  to 
"  the  arrangement  of  crystals  during  the  movement  of  the 

*  Geology  of  Canada,  1863,  pp.  605.  867,  and  Amer.  Jour.  Science, 
1S04,  xxxviii.,  17.J-178. 


(• 


VI.] 


OF  CRYSTALLINE   HOCKS. 


211 


half-liquid  crystalline  mass,  but  it  may  in  some  instances 
arise  from  the  subsequent  formation  of  crystals  arranged 
in  parallel  j^lanes."  * 

§  29.  The  feldspars  mentioned,  as  shown  by  the  pub- 
lished analyses  by  the  writer,  are  near  in  composition  to 
labradorite.  The  composite  rocks  described  also  contain, 
besides  pyroxene,  more  or  less  magnetite  and  raenacanite, 
with  chrysolite.  This  last  specie?  is  for  the  most  part 
distributed  sparsely  through  these  rocks,  but  occasionally, 
like  the  pyroxenic  element,  occurs  in  predominant  quan- 
tity. An  example  of  this  is  seen  in  a  coarsely  granitoid 
chrysolitic  aggregate,  exposed  witli  the  same  characters, 
over  an  area  of  many  hundred  square  feet,  on  Montarville. 
The  chrysolite  in  this  rock  is  in  irregular  crystalline 
masses  from  five  to  ten  millimetres  in  diameter,  and  was 
separately  analyzed,  as  was  the  black  pyroxene,  in  still 
larger  and  well  defined  crystals  from  the  mass,  and  also 
the  feldspathic  element,  selected  as  carefully  as  possible. 
For  an  analysis  of  the  rock  as  a  whole,  it  was  attacked  in 
fine  powder  successively  by  dilute  sulphuric  acid  and  by 
a  weak  solution  of  soda,  the  portions  thus  dissolved 
being  analyzed  separately,  as  well  as  the  insoluble  residue. 
The  relative  proportions  of  these  being  55.0  per  cent  of  the 
former  and  45.0  of  the  latter,  it  became  possible  to  calcu- 
late the  composition  of  the  rock  as  a  whole. 

*  Farther  Illustrations  of  this  are  given  by  the  author  In  a  communi- 
cation to  the  Boston  Society  of  Natural  History,  January  7,  1874: 
"Among  these  was  a  specimen  shown  from  Groton,  Connecticut,  in 
which  a  large  angular  fragment  of  strongly  banded  micaceous  gneiss  is 
enclosed  in  a  fine-grained  eruptive  granite,  the  mica  plates  in  which  are 
so  arranged  as  to  show  a  beautiful  and  even  stratification  in  contact  with 
the  broken  edges  of  the  gneiss,  but  at  right  angles  to  the  strata  of  the 
latter.  Another  example  is  afforded  by  the  eruptive  diabase  from  the 
mesozoic  sandstone  of  Lambertville,  New  Jersey,  which  is  conspicuously 
marked  by  light  and  dark  bands,  due  to  the  alternate  predominance  of 
one  or  the  other  of  the  constituent  minerals ;  and  still  another  is  a  fine- 
grained dark  micaceous  dolerite  dike  from  the  Trenton  limestone  at  Mon- 
treal, in  which  the  abundant  laminsB  of  mica  (probably  biotite)  are 
arranged  parallel  to  the  walls  of  the  dike."  Chem.  and  Geol.  Essays,  p. 
18C. 


I  I'.i 


m 


>■ 


:/ ! 


•MHIti 


212 


THE  GSNETIC  HISTORY 


[VI. 


§  30.  In  the  following  table,  I.  is  the  composition  of  the 
feldspar ;  II  the  pyroxene ;  and  III.  the  chrysolite ;  IV.  the 
soluble  portion  (55.0  per  cent),  chiefly  chrysolite ;  V.  the 
insoluble  portion  (45.0  per  cent) ;  VI.  the  rock  as  a  whole, 
including  an  undetermined  amount  of  titanic  oxyd  with 
the  iron-oxyd.  For  the  purposes  of  comparison  we  give 
under  VII.  the  composition  of  the  supposed  basic  magma 
of  the  earth's  interior,  as  deduced  by  Bunsen  from  the 
mean  of  several  analyses  of  basic  eruptive  rocks,  and 
under  VIII.  the  composition  of  the  same  as  calculated  by 
Durocher,  who,  however,  admits  a  range  in  proportions 
through  geologic  time  which  includes  the  figures  adopted 
by  Bunsen.  The  last  five  analyses  are  :\ecessarily  calcu- 
lated for  one  hundred  parts,  and  the  whole  of  the  iron  is 
represented  as  ferrous  oxyd,  although  an  unknown  pro- 
portion exists  in  a  higher  state  of  oxydation. 


i  ■■  M' 


I. 

II. 

III. 

IV. 

Silica      .    .    . 

53.10 

49.40 

37.17 

37.30 

Alumina     .    . 

26.80 

6.70 

— 

3.00 

Lime      .     .     . 

11.48 

21.88 

— 

— 

Magnesia    .     . 

.72 

13.06 

39.68 

33.50 

Ferrous  oxyd  . 

1.35 

7.88 

22.54 

26.20 

Soda  .... 

4.24 

.74 

— 

— 

Potash   .    .     . 

.71 

— 

— 

— 

Volatile      .    . 

.60 

.50 

— 

— 

99.00 

100.11 

99.39 

100.00 

V. 

VI. 

VII. 

VIIL 

Silica   .    .    . 

.    49.35 

42.70 

48.47 

51.5 

Alumina  .    .    . 

18.92 

10.16 

14.78 

16.0 

Lime    .    .    . 

.    18.36 

8.27 

11.87 

8.0 

Magnesia 

6.36 

21.29 

6.89 

6.0 

Ferrous  oxyd 

,      4.51 

16.45 

15.38 

13.0 

Alkalies   .    . 

2.50 

1.13 

2.61 

4.0 

100.00 


100.00 


100.00 


§  31.  The  process  which  has  thus  given  rise  in  parts  of 
a  mountain  mass  of  dolerite  to  considerable  areas  of  a  rock 
containing  over  21.0  of  magnesia,  and  more  than  one  half 


HI 


VI.] 


OP  CRYSTALLINE  ROCKS. 


213 


its  weight  of  chrysolite,  find  in  other  parts  of  the  same 
mass  to  an  aggregate  of  pyroxene  and  labradorite  almost, 
and  in  some  cases  wholly,  destitute  of  chiysolite,  is  readily 
explained  if  we  admit  a  separation  from  a  still  fluid  mass 
of  the  previously  crystallized  and  heavier  chrysolite  by  a 
process  like  that  imagined  by  Durocher.  It  will  be 
noticed  that  the  insoluble  and  non-chrysolitic  portion 
separated  from  the  Montarville  rock,  V.,  is  near  in  compo- 
sition to  an  ordinary  dolerite,  or  to  the  normal  basic  types 
of  Bunsen  and  Durocher.  We  may  conjecture  that  iloler- 
ites  of  average  composition  are,  perhaps,  themselves  pro- 
ducts separated  by  eliquation  from  a  more  chrysolitic 
aggregate. 

§  32.  The  segregation  of  groups  of  crystals,  which 
takes  place  in  the  devitrification  of  glasses,  shows,  within 
narrow  limits,  the  process  of  differentiation  through  crys- 
tallization in  a  homogeneous  mass.  The  operation  of  this 
process  on  a  larger  scale,  giving  rise  to  remarkable  miner- 
alogical  differences,  is  well  shown  in  the  careful  studie? 
by  Fouqud,  in  1873,  on  the  recent  eruptive  rocks  from 
Santorin.  The  ordinary  type  of  these  lavas  examined  by 
him  was  a  vitreous  mass  enclosing  crystals  of  feldspars, 
with  pyroxene,  chrysolite,  and  magnetite.  The  feldspar 
was  chiefly  labradorite,  but  its  association  with  crystals 
of  albite,  and  with  some  anorthite,  was  established.  Druses 
in  this  same  rock  were,  however,  filled  with  anorthite, 
associated  Avith  a  pyroxene  and  a  chrysolite,  both  differing 
from  those  contained  in  the  paste  in  being  less  dense  and 
in  containing  less  ferrous  oxyd.  In  an  obsidian-like  rock 
from  the  same  region  were  rounded  masses,  sometimes  a 
metre  in  diameter,  gray  in  color,  and  made  up  of  crystal- 
line anorthite,  with  pyroxene,  chrysolite,  sphene,  and 
magnetite,  Avith  very  little  paste.  The  small  portions  of 
alumina  found  in  the  analyses  of  these  pyroxenes  were 
apparently,  according  to  Fouqu^,  derived  from  adherent 
anorthite,  but  another  variety  of  pyroxene,  seemingly  very 
pure,  and  freed  from  anorthite,  contained  12.4  per  cent  of 


:i^:' 

,':?-i; 

;':!• 

■  t' 


THE  GENETIC  HISTORY 


IVI. 


214 

„,„,,  _a  trao  aluminous  ry«>f  "^    ..,„,.,'  dvic  acia.wluoh 

veaaUy  attacks   the  <;°;'^S^f  J  '„v,,aaorite,  an.l  anorth.te, 
alike  the  vitreom  pas  e  atote^  ,,„,y,„ute,  winch, 

but  leaving  ^'=1""^*'  \ Suy^taekea  by  the  acid ,•  or, 
Uke  aun^luV-oli^. ''';'' ^"'fS  its  action.  ,     .      , 

like  stauvolite  and  .jrcon,  '««'^'  „{  ^^e  hypothesis  o£ 

S  88.  Dniochev,  in  h  s  sta  einen  ^^^^^^^  ^^  ^^^^.^j^  ^j^,, 

eliquation  as  applied  to  J'"l«  ,,  j^  ,,„t  an  illustration, 
Jeess  of  ^eS''-g:'»'°^r  he  nuestion  of  differentiation, 
■aises,  in  connection  ™  *7f„„„„l„de8  from  his  com- 
auothev  not  less  impo.tant-     ""  „,e  of  the  ages 

parative  studies  that,  "  m  the  ^^\  ^,,Ms  fi-om 

which  divide  the  piimaiy  ami  u  composi- 

th  othe.-,"  theve  have  heen  chan  -^^  ^^^  ^^ 
tion  of  the  fluid  ™:'^' ^'"™  "„f  the  acidic  layer-the 
and,  nioreovev,  tha  in  the  cas  ^^^_.the.e  was  a 

source  of  the  gram  ic  '''^^^  *3redths  in  the  proportion 
diminution  of  eight  or  nn^  »  „^^,,,,  while  the  propoi- 
o£  silica,  and  of  one-fitth  >"  «'« J      ^i„„,t  doubled,  and 

ti„„s  of  lime  and  """-"^^X  rf»"S'=«'  -''""''"^ '" 
that  of  the  soda  tripled.     Sunda      ^     b^  ,.,j„,,ented  by 

l,i™,have  taken  place    "*%;^  the  comparative  study 

dokultes,  te^'l'^' ™f  P  f't'l'i^  the  ferro-ealeiferous  layer 
of  which  he  concludes  that  application 

,nd  94  Pe^-^^^^^^^^g  Jiies,  lime,  magnesia,  iron  ^^^«'  j,,^^, 

;^[rBerhtrS?'Acad.  Wissenschaft,  U,  1885. 

Nov.  6, 1885.) 


Mf^ 


▼14 


OP   CRYSTALLINiS  ROCKS. 


Cl-i 


from  the  primary  to  the  tertiary  period  .  .  .  there  was  a 
sensible  diminution  of  silica  and  potash,  and  a  notable 
augmentation  of  soda  and  lime."  Of  these  changes  "  the 
diminution  of  silica  and  potash  in  the  modern  rocks,  both 
of  the  acidic  and  basic  groups,"  was  by  Durocher  exi)lained 
by  supposing  that  while  these  imaginary  igneous  layers 
remain  distinct  from  each  other,  there  is,  nevertheless, 
in  each  a  partial  separation  of  these  elements  by  gravity, 
resulting  in  an  accumulation  of  silica  and  potash  in  their 
upper  portions,  and  of  lime  in  their  lower  portions.  The 
augmentation  in  the  proportion  of  soda  was  by  him  re- 
ferred to  a  special  and  independent  cause,  the  supposed 
"intervention  of  sea-water  in  the  formation  of  igneous 
products  during  the  later  geological  periods,"  which,  as 
he  writes,  would  explain  "the  considerable  increase  of 
soda  in  the  more  modern  of  the  igneous  rocks,  whether 
they  be  derived  from  the  acidic  or  the  basic  layer." 

§  34.  While  Durocher  included  in  the  category  of 
eruptive  rocks  certain  masses,  such  as  those  of  magnetite, 
serpentine,  and  various  amphibolic  rocks,  for  which  an 
igneous  origin  is  not  admissible  (so  that  some  of  his  data 
may  be  questioned),  the  correctness  of  his  important 
generalizations,  which  suggest  a  vast  geogenic  problem, 
cannot  be  contested.  As  regards  his  proposed  explana- 
tion, it  is  easy  to  conceive  that  a  separation  by  specific 
gravity  might  possibly  cause  such  variations,  alike  in  the 
acidic  and  the  basic  layer,  that  the  ejections  in  the  course 
of  ages  from  successively  lower  portions  of  each  of  these 
would  show  the  gradual  diminution  observed  in  the  pro- 
portions of  silica  and  potash,  as  well  as  the  augmentatio.i 
of  lime.  To  this  ingenious  explanation,  however,  it  is  to 
be  objected  that  it  is  based  upon  the  unproved  and,  in 
the  opinion  of  many  modern  philosophers,  the  untenable 
hypothesis  of  a  molten  substratum,  and,  moreover,  one 
divided  into  two  distinct  zones.  The  whole  of  the  phe- 
nomena in  question,  moreover,  admit  of  a  simpler  and,  it  is 
believed,  a  more  probable  explanation   by  the    crenitic 


216 


THE  GENETIC  HISTOltY 


[VI. 


M'? 


hypothesis.  This,  as  we  have  seen,  supposes  a  constant 
and  progressive  differentiation  of  an  original  basic  plu- 
tonic  mass  through  the  action  of  water,  which  removes 
therefrom  in  tlie  elements  of  orthoclase  and  quartz,  —  the 
chief  constituents  of  granitic  rocks, — preponderant  pro- 
portions of  iiilica  and  potash;  an  action  which  would 
result  at  last  in  the  partial  exhaustion  of  the  lixiviated 
portion  of  the  basic  rock,  which,  with  the  diminution  of 
the  amount  of  available  silica  and  potash,  would  finally 
yield  to  the  solvent  action  of  the  waters  only  the  elements 
of  the  more  basic  feldspars.  As  a  result  of  this  continued 
process,  the  crenitic  products  themselves  will  naturally 
show  a  diminution  in  the  proportions  of  silica  and  potash, 
by  reason  of  the  progressive  exhaustion  of  the  source  of 
these,  while  this  residual  portion  of  basic  rock  will  not 
only  exhibit  a  reduction  in  the  proportions  of  silica  and 
pota'^h,  but  a  relative  increase  in  the  proportion  of  lime. 
Moreover,  the  sodium  and  magnesium-chlorids  which,  from 
the  results  of  sub-aerial  decay,  find  their  way  into  the  sur- 
face-waters, which  subsequently  pass  downwards  in  the 
process  of  lixiviation,  may  by  double  exchange  effect  the 
displacement  of  potash  and  the  fixation  of  soda  and  mag- 
nesia in  the  basic  mass,  as  explained  farther  on. 

§  35.  This  hypothesis  thus  explains  at  the  same  time 
the  origin  of  the  highly  silicic  and  potassic  rocks,  repre- 
sented by  the  granites,  and  the  conversion  of  the  original 
plutonic  stratum  into  a  more  and  more  basic  material,  pro- 
gressively richer  in  alumina,  soda,  lime,  and  magnesia.  It 
moreover  requires  that  the  long-continued  lixiviation  of 
a  given  area  of  plutonic  rock  should  at  length  reach  a 
point  at  which  water  could  no  longer  remove  from  it  the 
elements  of  orthoclase  and  quartz.  With  the  disappear- 
ance of  the  latter  would  come  the  elements  of  the  more 
basic  feldspars,  such  as  andesite  and  labradorite,  as  well  as 
protoxyd-silicates,  which  together  predominate  in  the 
norites  and  the  diorites,  characteristic  crenitic  rocks  of 
the  later  crystalline  series,  as  the  Norian  and  Huronian, 


n.1 


OF  CRYSTALLINE  ROCKS. 


217 


i''^ 


which  succeed  the  granitea  anil  the  granitoid  gneisses  of 
the  earlier  [)eriods. 

Tlie  crenitio  hypothesis,  as  we  have  elsewhere  seen,  in- 
volves the  conception  that  all  trachytic  and  granitic  rocks 
are  primarily  of  crenitic  origin,  and  that  penetrating  gran- 
itic masses,  when  not,  as  is  the  case  with  most  granitic 
veins,  directly  crenitic  or  endogenous  masses,  are  displaced 
portions  of  older  crenitic  deposits.  The  first-formed 
granitic  layer  itself,  it  is  held,  may  become  softened  under 
the  combined  influences  of  wate"  and  internal  heat,  and, 
being  then  displaced,  may  appear  in  an  eruptive  form. 

§  3G.  The  question  here  arises  as  to  the  respective 
parts  which  crenitic  action,  on  the  one  hand,  and  crystalli- 
zation and  eliquation,  on  the  other,  may  play  in  the  genesis 
of  various  types  of  crystalline  rocks.  It  is  apparent,  from 
the  illustrations  which  we  have  given,  that  by  the  latter 
process  aggregates  could,  in  paleozoic  times,  be  formed  in 
which  chrysolite  makes  more  than  one  half  the  weight  of 
the  mass,  and  others  in  which  either  pyroxene  or  labra- 
dorite  may  largely  predominate.  The  texture  and  the  gen- 
eral facies  of  these  different  mineral  aggregates,  not  less 
than  their  geognostic  relations,  however,  suffice  to  distin- 
guish them  from  crenitic  deposits  of  somewhat  similar 
composition.  It  was  from  a  failure  to  recognize  these 
differences  that  the  original  Wernerians  denied  or.  min- 
imized the  significance  of  igneous  rocks,  on  ^he  one  hand, 
and  that  the  later  plutonists  of  both  schools,  on  the 
other  hand,  have  argued  the  igneous  origin  of  rocks  of 
manifestly  crenitic  origin.  The  Wernerir  is,  from  the 
stratiform  structure  of  gneiss,  which  they  ascribed  to  its 
aqueous  origin,  argued  for  a  similar  origin  for  the  granite 
into  which  it  appears  to  graduate,  while  the  plutonists 
from  an  analogous  structure  in  undoubtedly  igneous  rocks 
conclude  to  the  igneous  origin  of  gneiss.  We  have 
already  noticed  this  laminated  or  stratiform  character  in 
Plutonic  rocks,  the  true  significance  of  which  as  evidences 
of  igneous  flow  should  not  be  lost  sight  of  (page  210). 


t«; 


218 


THE  GENETIC  HISTORY 


[vr. 


/ 


■M 


fV       ,'.i 


§  37.  It  must  be  kept  in  mind  that  the  cronitic  p'":cesa, 
unlike  eliquation,  modifies  the  primary  mass  not  only  by 
abstraction  bnt  by  addition,  since  the  surface-watev,  which, 
by  the  hypothesis,  is  the  dissolving  agent,  will  bring  with 
it  in  solution,  in  varying  propoitions,  salts  of  calcium  and 
magnesium,  of  potassium  and  of  sodium,  the  action  of  all 
which  upon  the  heated  plntonic  mass  will  effect  certain 
interchanges,  resulting  in  the  fixation  of  bases  like  mag- 
nesia, whose  3ilicated  compounds  are  comparatively  insol- 
uble in  the  circulating  waters,  and  perhaps  in  a  substitu- 
tion of  soda  for  lime.  It  is  not  improbable  that  jiotassic 
solutions  from  some  hical  source  *  could  thus  l)e  introduced, 
and  give  rise  by  their  action  upon  a  doleritic  mass,  either 
integral  or  partially  differentiated  by  eliquation,  to  a  ma- 
terial so  rich  in  potash  as  to  furnish  the  elements  of  leu- 
cite,  —  \Vhich  has  the  oxygen-ratios  of  andesite. 

§  38.  The  genesis  of  rocks  like  phonolite,  which  are 
essentially  made  up  of  a  feldspar  having  the  orthoclase- 
ratios,  with  an  admixture  with  a  more  basic  silicate,  as 
nephelite  or  a  zeolite,  can,  however,  hardly  be  explained 
save  as  an  educt  of  crenitic  action,  like  trachyte  and  gran- 
ite. It  represents,  however,  a  period  in  the  history  of  the 
plutonic  mass  when,  from  a  diminution  of  silica,  the  pro- 
duction of  quartz  ceases,  and  more  basic  feklspathi')  or 
zeolitic  compounds  begin  to  replace  the  orthoclase.  When 
from  compounds  like  these,  in  which  the  proportion  of 
protoxyds  to  alumina  falls  below  the  normal  oxygen-ratio 
of  1  :  3,  we  pass  to  others,  like  the  muscovitic  micas,  most 
tourmalines,  and  the  pinite-like  minerals,  with  a  dimin- 
ished proportion  of  protoxyds,  we  have  probably  in  all 

*  While  In  ordinary  spring-waters  the  proportion  of  potassium  to  so- 
dium salts  is  small,  seldom  exceeding  two  or  three  hundredths  of  these 
bases,  calculated  as  chlorids,  I  have  shown  that  in  an  alkaline  spring- 
water  from  paleozoic  shales  at  St.  Ours,  Quebec,  containing  in  a  litre 
about  0.3  gramme  of  alkalies,  chiefly  as  carbonates  and  chlorids,  the  potas- 
sium thus  calculated  equalled  25  per  cent.  In  the  case  of  the  water  of 
the  St.  Lawrence  River  it  equals  10  per  cent,  and  of  the  Ottawa  River  32 
per  cent.  See  for  a  discussion  of  the  question  of  potassium  in  natural 
waters  the  writer's  Chem.  and  Geol.  Essays,  pp.  135-137. 


m 


OP  CUYSTALMNE   HOCKS. 


219 


cases  to  do  either  with  crenitic  products  or  with  tlio  direct 
results  of  sub-aerial  (h>cay. 

§  89.  Fouc^ud  and  Michel  L(ivy,  in  tlioir  recent  experi- 
ments, have  shown  us  how  to  form  artiliciully,  from  mix- 
tures in  igneous  fusion,  in  which  the  pro[)ortions  of  ele- 
ments, were  pre-arranged,  crystalline  aggregates  eontaini'ig 
leucite  with  lahradorite,  pyroxene,  magnetite,  and  spinel, 
and  others  holding  chrysolite  in  similar  associations. 
The  problem  which  lies  behind  their  discovery  is  to  deter- 
mine how  the  materials  are  so  grouped  in  nature's  labora- 
tory as  to  yield  the  mixtures  necessary,  in  the  (  'ic  case,  for 
the  production  of  a  leucitophyro  and,  in  the  other,  for  a 
chrysolitic  dolorito.  The  research  of  the  natural  processes 
by  which  these  combinations  are  reached  has  been  the 
object  of  the  preceding  ini^uiry  hito  the  results  of  elitiua- 
tion,  on  the  one  hand,  and  of  the  solvent  and  replacing 
action  of  percolating  waters,  on  tlu;  other. 

§  40.  It  is  farther  to  be  noted  that  the  experiments  of 
Fouqud  and  jNIichel  L6vy  were  made  by  the  slow  cooling 
of  mixtures  from  simple  igneous  fusion,  and  the  question 
must  here  be  raised  how  far  these  reactions  would  be 
affected  by  the  intervention  of  water;  in  other  words, 
whether,  as  maintained  by  Poulett  Scrope,  Scheerer,  Elie 
de  Beaumont,  and  many  others,  water  is  not  always  pres- 
ent in  the  mass  of  igneous  rocks.  So  far  as  experiments 
go,  the  process  of  cooling  from  simple  igneous  fusion 
would  seem  to  be  inadequate  to  account  for  the  origin  of 
manj"-  of  the  minerals  of  eruptive  rocks.  Fouqud  and 
Michel  Ldvy  inform  us  that  they  "  have  vainly  sought  to 
produce  by  igneous  fusion  rocks  with  quartz,  orthoclase, 
albite,  white  or  black  mica,  or  amphibole,"  *  although  the 
occasional  accidental  production  of  orthoclase  as  a  furnace- 
product  has  been  noticed.  The  presence  of  albite  in  the 
recent  lavas  o^  Santorin  in  association  with  lahradorite, 
pyroxene,  and  chrysolite  has  been  shown  by  Fouqud 
(§  32),  and  its  probable  occurrence  in  a  diabase  has  been 

*  S3rnth&se  des  Mineraux  ct  des  lloches,  p.  75. 


I 


mmmmmmm 


\'   ?: 


i , 


li 


..     U 


'i  i 


m- 


m'l 


220 


THE  GENETIC  HISTORY 


[VI. 


pointed  out  by  Hawes.*  Both  orthoclase  and  albite 
have,  however,  been  formed  in  the  wet  way,  at  elevated 
temperatures,  under  pressure  (awie,  page  157)  ;  and  pyrox- 
ene, while  readily  generated  from  the  products  of  igneous 
fusion,  was  got  by  Daubr^e  by  the  action  of  superheated 
water  on  glass  at  the  same  time  with  crystallized  quartz 
and  magnetite  or  spinel  (ihid.^  V^g^  148).  The  frequent 
occurrence  of  pyroxene  in  veinstones,  in  intimate  associa- 
tion with  orthoclase,  qvni,rtz,  apatite,  and  calcite,  suffices 
to  show  its  aqueous  origin,  in  common  with  all  of  these 
species.  In  like  manner,  magnetite,  which  is  readily 
formed  in  fused  basic  mixtures,  is  found  crystallized  with 
orthoclase  and  quartz,  with  apatite  and  pyrite,  in  granitic 
veinstones.  Moreover,  the  fact  of  its  association  with 
garnet,  and  with  zeolitic  minerals,  in  the  secretions  of 
basic  rocks  suffices  to  prove  that  magnetite,  as  well  as 
hematite,  may  be  formed  by  aqueous  action.  Chrysolite, 
also,  is  produced  by  igneous  fusion,  but  its  presence  in 
crystalline  limestone  in  the  form  of  forsterite,  and  in 
massive  magnetite  as  hortonolite,  shows  that,  like  the 
related  and  similarly  associated  species,  chondrodite,  it 
may  be  formed  in  the  presence  of  water  (Essay  X.,  § 
122-124). 

§  41.  The  evidences  of  the  intervention  of  water  in 
eruptive  rocks  have  since  the  time  of  Scropo  been  too  often 
pointed  out  to  need  repetition  here.  Its  elements  may 
even  be  retained  in  fused  compounds  at  the  temperature  of 
ignition,  under  the  ordinary  atmospheric  pressure,  as  seen 
not  only  in  the  hydrate  and  the  acid-sulphate  of  potas- 
sium, but  in  certain  vitreous  borates  of  sodium  and  potas- 
sium, long  since  described  by  Laurent,  which  at  a  red 
heat  and  in  tranquil  fusion  hold  an  amount  of  hydrogen 
equal  to  1.2  and  1.3  hundredths  of  water,  and  are,  under 
these  conditions,  slowly  decomposed  by  metallic  iron, 
with  abundant  disengagement  of  hydrogen  gas,  which 
burns  with  a  green  flame  from  the  presence  of  combined 

*  See  Essay  VIII.,  §  75. 


VI.] 


OF  CRYSTALLINE  EOCKS. 


221 


boron.*  That,  under  greater  pressure,  water  may  be  held 
by  other  compounds,  such  as  silicates,  is  undoubted.  Hy- 
drous glasses  like  pitchstone  and  perlite  are  examples  of 
these,  and  differ  from  obsidian  in  containing  three  or  four 
hundredths  of  water. 

§  42.  The  late  researches  of  Tilden  and  Shenstone  on 
The  Solubility  of  Salts  in  Water  at  High  Temperatures 
throw  much  light  on  the  geological  relations  of  water. 
While  the  solvent  power  of  this  liquid  rapidly  increases, 
when  under  pressure,  at  temperatures  above  100°  C,  they 
have  shown  that  "the  increase  of  solubility  follows  the 
order  of  tlie  fusing-point  of  the  solid."  Thus,  of  potas- 
sium-iodid,  which  melts  at  634°,  100  parts  of  water  at  180° 
dissolve  327  parts,  while  of  barium -chlorate,  melting  at 
400°,  100  parts  of  water  at  180°  dissolve  526,  parts.  Of 
potassium-nitrate,  melting  at  339°,  100  parts  of  water  at 
120°  dissolve  495  parts,  or  nearly  five  times  its  weight ; 
while  of  silver-nitrate,  whose  fusing-point  is  217°,  100 
parts  of  water  at  125°  dissolve  1622.5  parts,  and  at  133° 
1941.4  parts,  or  nearly  twenty  times  its  own  weight.  Of 
certain  substances  it  can  be  said  that  they  are  infinitely 
soluble  at  certain  temperatures.  This  is  true  of  the  deca- 
hydrated  sodium-sulphate,  which  melts  at  34°,  and  nearly 
true  for  benzoic  acid.  This  substance,  which  melts  at 
120°,  requires  for  its  solution  600  parts  of  water  at  0°  and 
25  parts  at  100° ;  but  when  heated  in  a  sealed  tube  to  a 
few  degrees  above  its  fusing-point  it  is  miscible  with 
water  in  all  proportions.  These  heated  solutions,  in  the 
case  at  least  of  barium-chlorate  and  potassium-nitrate,  are 
described  as  notablj'  viscous,  a  condition  which  indicates 
that  they  are  perhaps  colloidal.f 

§  43.  From  these  results  it  is  easy  to  conceive  what 
might  be  expected  at  elevated  temperatures  with  mate- 

*  The  potassium-borate  in  question,  apart  from  combined  water,  con- 
tained boric  oxyd  .58.0,  potash  16.3,  giving  the  oxygen-ratio  72:5,  and 
tlie  sodiuni-borate  liati  tlie  same  atomic  ratios.  Aug.  Laurent,  Compte 
Rendu  des  Travaux  de  Chimie,  1850,  pp.  .36-42. 

t  Philos.  Trans.,  1884,  part  1,  pp.  23-36. 


lilt  ^'ii  i 

mil 


222 


THE  GENETIC  HISTORY 


[VI. 


M! 


!  I 


:;;  I 


rials  as  insoluble  at  ordinary  temperatures  as  quartz  or 
the  natural  silicates.  .A  few  hundredths  of  water  at  several 
hundred  degrees  Centigrade  would  probably  convert  these 
into  a  viscid  fluid,  from  which,  as  from  an  anhydrous 
magma,  by  rest  or  by  partial  cooling,  definite  compounds 
might  successively  crystallize;  —  the  mixture  becoming,  to 
use  the  simile  of  Poulett  Scrope  in  speaking  of  lavas,  like  a 
syrup  holding  grains  of  sugar.  From  such  mixtures  par- 
tially cooled,  or  from  a  heterogeneous  plutonic  mass 
impregnated  with  water  and  not  yet  raised  to  the  full 
temperature  of  solution,  or  what  has  been  aptly  termed 
"igneo-aqueous  fusion,"  the  more  soluble  portions,  re- 
moved by  percolation  or  by  diffusion,  we  conceive  to  have 
constituted  the  liquids  which  in  earlier  times  produced  the 
various  creuitic  rocks.  The  fact  that,  as  shown  b}'-  Sorby,* 
pressure  augments  the  solvent  power  of  water,  irrespective 
of  temperature,  should  not  be  lost  sight  of  in  this  connec- 
tion. The  remarkable  observations  of  Tilden  and  Shen- 
stone  serve  to  explain  and  to  justify  the  view  of  the 
intervention  of  water  in  giving  liquidity  to  various  erup- 
tive rocks,  originally  put  forward  by  Poulett  Scrope,  and 
afterwards  ably  maintained,  anong  others,  by  Scheerer 
and  Elie  de  Beaumont.f 

§  44.  We  have  already  noticed  the  banded  structure 
(p.  210)  which  often  results  from  movement  in  the  extru- 
sion of  more  or  less  differentiated  masses  of  eruptive  rocks, 
simulating  that  produced  by  the  separation  from  water 
either  of  mechanical  sediments  or  of  crystalline  deposits. 
It  is  important  in  this  connection  to  distinguish  between 
the  latter  two  processes,  and  to  insist  upon  the  more  or 
less  concretionary  character  of  the  matters  separated  from 
solution,  often  shown  in  the  lenticular  shape  of  beds  of 
this  character,  and  well  displayed  in  the  crystalline  schists. 

*  Proc.  Roy.  Soc.  London,  xii.,  538. 

t  Scrope,  Jour.  Geol.  Soc.  London,  xii.,  326.  Scheerer,  Bull.  Soc. 
Geol.  de  Franre,  1845,  iv.,  468,  and  filie  de  Beaumont,  ibid.,  1249  et  seq. 
See  farther  the  author's  Chera.  and  Geol.  Essays,  188-101,  and  also  5,  6, 
for  farther  references  to  the  literature  of  the  subject. 


N 


VfcJ 


OF  CRYSTALLINE  FOCKS. 


223 


The  conditions  under  which  these  were  laid  down  from 
water  were  less  like  those  of  ordinary  sediments  than  of 
the  accumulations  of  crystalline  matter  in  geodes  and  in 
veins.  Many  facts  with  regard  to  the  banded  character 
of  mineral  veins  are  familiar  to  geologists,  and  the  strati- 
form character  of  such  deposits  has  often  been  remarked 
in  smaller  vein-like  masses.  I  have  elsewhere  called 
attention  to  the  fact  that  crystalline  masses  having  the 
relations  of  veinstones  may  assume  great  proportions,  and 
that  much  granitic  rock  often  regarded  as  eruptive  is  really 
of  concretionary  and  endogenous  origin,  and  discussed 
the  question  at  some  length  in  1871.*  Veins  of  this  kind 
were  then  described,  sixty  feet  in  breadth,  traversing  the 
gneisses  and  mica-schists  of  the  younger  gneissic  or  Mont- 
alban  series  in  New  England,  often  coarsely  crystalline 
and  banded,  and  evidently  concretionary,  but  sometimes 
so  finely  granular  and  homogeneous  in  portions  as  to  be 
quarried  for  architectural  purposes,  like  the  indigenous 
gneisses  of  the  series,  which  they  often  closely  resemble. 
Remarkable  examples  of  the  same  phenomenon  are  to  be 
met  with  in  the  older  gneissic  or  Laurentian  series,  some 
of  which  are  concpicuous  in  the  sections  of  these  rocks 
visible  in  the  caflon  of  the  Arkansas  Klver  and  elsewhere 
in  Colorado.  Still  more  striking  examples  are  met  with 
in  the  similar  gneisses  in  parts  of  Canada,  and  are  well 
displayed  in  Ottawa  County,  in  the  province  of  Quebec, 
where,  in  the  township  of  Buckingham,  veins  eighty  feet 
in  breadth,  and  made  up  almost  wholly  of  orthoclase  and 
crystalline  cleavable  magnetite,  traverse  for  considerable 
distances  the  stratified  gneiss  of  the  region.f 

§  45.  In  the  same  County,  and  near  the  Riviere  aux 
Li^vres,  are  the  great  veins  which  have  lately  been  exten- 
sively mined  for  apatite  in  what  is  known  as  the  Lidvres 
district.     Very  similar  veins  also  occur  a  short  distance 

*  Granites    and    Granitic  Veinstones,    Amer.    Jour.    Science,  1871. 
Granites,  Chem.  and  Geol.  Essays,  pp.  191-202. 
t  Geol.  Report  of  Canada,  1863-66,  pp.  20,  215. 


.' '  'i 


THE  GENETIC  HISTORY 


I     1 


\^    . 


vn. 

THE  GENETIC  Iii»xv.x.^ 
224  ^  .    ^g 

to  the  southwest,  along  ^^-f^^tt  Utou^Sct. 
of  Ontario,  in  what  may  be  «"«''        described  by  the 

The  veins  in  «* '^^raXC-ntly  in  1868,  in  1866, 
writer  as  eariy  as  1848,  and  subse|         J  ^^ 

Ind  in  1884.-     The  .«  ttn  ide'.ed  together,  w.l 
the  two  districts  which  may  be  ,^^  ^^^^  ^,^^^       j 

eerve  to  iUnstrate  '"'"/J^pa'  associates  of  the  apatite 
evystalline  rocks     Tlie  punc^pa  _  ortlioclase, 

in  tliese  districts  are   Py'^^^^^'^l.^ia^ot  the  localities  in 
quarts,  calcite,  and  pyae.    It  w  .lamination  m 

?1K  Rideau  J«t"f  •  "l2  i'p^  it  occurs  in  -  fl--\;» 
.e  shows  that     the  a  p  ^^^^^  „  ^^j^j^     a 


::eh  ...e  shows  that  ''^^  '^^ JwalW  while  "a 
the  stratification,  "»'!,'';'• '^„eial  contents  is  often  yery 
banded  -angeme",  "U riouTminerals      „,,a  ,o.netimes 
well  marked;    -*"^J,__  „£  which  the  calcite,  often 
occurring  in  alternate  layers,  <>'  ^^^^^  „j    a 

with  i»<=l"'l«'l  ,r  tmS  to<= '<'"^"     Farther  exam- 
coarsely  crystathne  1^»^^    '   ^^^^  hilateral  symmetry  of 
pies  were  then  given  »™^™8    ;     ^l  presence  in  them  of 
Lnv  of  the  veins,  and  *«  occas  o       i'       „         ^-^^^  of 
drusV   cavities.     Moreover,  althou  ^  ^^^  ,.,^^^. 

apatae  were  observed  ni  what  w  re    eg      ^^^  ^^^^^  ^^^^^ 

stone  beds  of  the  enclosing /^^^'^^  ^^^^  ,  ^  ^,_^  ^^.^tions, 
workable  deposits  of  »?'''»;«•  J„    guch  were  the  conclu- 
ai-e  confined  to  the  veins  on    ■  J        ^  ^^^^     ^^^^ 
sions  announced  by  the  w     er  ^^  ^^.^  j^^^. 

.luently,  in  ^'f'^^^J^'tt^M^^o.e^^'^"  ^rT:l 
district,  he  was  led  to  w"te  Hi  ^^^^.       j,^^  strata. 

apatite  are  in  S^'^^t  pait  '«  '"^^  fagmcnts  of  the  wall- 
a^nd  sometimes  including  anguta  g  ^^  ^^  g,,,;  of 
,o„k,-«Meh  IS  *e  clu^actens  ^^^^^_^  ^^  Uiterstratified 
the  region,- they  aie  '        _       132,  ,„d  for  1863-66, 

,  Geol  Survey  of  Cauada  Kepo't  forl8«,  P^     ^    ,^,_  ^„,  ^ 
„/2?^2»°»'»««*Syo<C»»»^»';f'i|%p.i5«-468.    See  farther, 

B.  J.  Harrington,  «eP«"     ,    1882-83-84,  J.,  PP-  ^'^^^  ^"^r" 
SS^W^nroi^-lSo^^^^t'oi  - -adUn  ap.Ue  .epulis. 


VI.] 


OF  CRYSTALLINE   ROCKS. 


225 


in  the  pyroxene-rock  of  the  region."  With  regard  to  cer- 
tain apprrently  bedded  deposits  of  apatite  it  was  farther 
said,  "  1  am  disposed  to  look  upon  [them]  as  true  beds 
deposited  at  the  same  time  with  the  enclosing  rocks," 
whicli  were  described  as  "  chiefly  beds  of  pyroxene-rock, 
generally  pale  green  or  grayish-green  in  color,  with  mix- 
tures containing  quartz  and  orthoclase,  and  distinctly 
gneissoid  in  structure." 

§  46.  I  am  careful  to  emphasize  this  apparent  contra- 
diction between  the  assertion  of  tlie  truly  endogenous 
character  of  the  deposits  in  which  apatite  occurs  with  pyr- 
oxene, phlogophite,  orthoclase,  quartz,  and  calcite,  and 
that  of  the  interstratification  of  the  same  apatite  in  con- 
temporaneous layers  with  a  gneissoid  pyroxenic  rock,  for 
the  reason  that  both  statements  are  strictly  true,  and  that 
in  their  reconciliation  light  will  be  thro-wn  on  the  great 
problem  of  the  genesis  of  these  crystalline  aggregates. 
The  mining  operations  on  a  large  scale  in  these  apatite 
deposits  in  the  Lidvres  district,  especially  in  the  years 
1883-1885,  have  in  fact  shown  that  the  stratiform  pyrox- 
enic masses  are,  like  the  associated  orrhoclase-rock,  the 
apatite,  and  the  calcite,  subordinate  parts  of  veins,  which 
assume  in  many  cases  vast  proportions,  and  at  the  same 
time  have  in  parts  of  their  mass  a  banded  structure  much 
resembling  that  of  the  enclosing  gneiss.  Illustrations  of 
this  condition  of  things  abound  at  the  great  oi)en  cuttings 
for  exploration  and  for  mining  which  have  been  made  at 
the  High  Rock,  the  Union,  and  the  Emerald  mines,  in 
Portland  and  Buckingham  townships,  on  the  Lievres 
River.*     At  the  first-named  locality  the   nearly  vertical 

*  The  workings  at  each  of  the  three  mines  named  haA'e  yielded  five 
thousand  tons  or  more  of  commercial  apatite  annually  for  three  or  four 
years,  and  consist  for  the  most  part  of  open  cuttings,  in  some  cases  to 
depths  of  over  one  hundred  feet,  causing  the  uncovering  or  displacement 
of  great  portions  of  the  accompanying  rock-masses.  In  otlier  mines  in 
this  region,  also  very  productive,  shafts  have  been  sunk  on  apatite 
bands  in  these  veins  to  depths  of  one  hundred  and  fifty  and  two  hundred 
feet. 


\l 


:i » 


'  '!ii 


i 


jl      K 


THE  GEI^ETIC  HISTORY 


tvi. 


"^  s  4T.   A  study  »«  '*<>""  "^ju  heln  to  an  understand- 
reLn  (wWch  are  not  mn  ed)  w.U  ne  ^^^  ^^  ^^.^^ ^ 

:|rf  the  nature  and  -'';»," k  mine,  these  lesser 
fo?  apatite.    As  seen  at  the  High  .^  ^-^^i,  and 

vein,  are  fron.  a  few  '"**' *'!  ^^'grnatite,  often  includ- 
^e  chiefly  of  a  hinary  granite  o^J"  ^^^^  „ear  their 
■^g  portions  of  *e  ^^'^tl^r  of  two  or  three  feet,  a 
boriers  presenting,  *"",^  t^'J^ents  of  gneiss  fro™  o;« 
veritable  hveccia  "t  '"ff '^"^^^         ^^.„^^„„,  ,„«  „de8 

to  six  inches  in  ^l'''">'=\'',  ;  J^  ^te  and  the  other  reddish 
two  feldspars,  one  ™'="g  J„ieavable  masses.    A  little 
the  latter  forming  cons  deaWec  ._^  ^e  vems, 

„Wte  mica  is  ^'f  .^""f^^'ion,  hold  portions  of  green 
whicii,  in  parts  of  ^^'^J.t!"!.,  slender  strings  runmng 
cleavaUe  vy^'^^T'^tZMs  filling  the  greater  part 
with  tlie  strike,  hut  »  ."""^  . ,?" ',,,„s  of  white  feldspar, 
If  the  vein,  and  "f »'!»'?  ""^X^  fine  and  large  crys- 
^ul  small  masses  of  greenish  apatite^  „„,eover,  occa- 

™    of  which,  and  others  of  B™ ^"Ji  "    ,„itio  veinstone. 
Inally  found  directly  imbedded  in  ttie  g  .  _^  ^^^^^^^ 

'  Td  Veins  of  vitreous  quartz  afoot  or  „^^„„,, 

J  met  with  in  the  i™— ™*of  feldspar,  hy  an  ' 
enclose  crystals  "^  =>?*"'' "'^^  i„to  the  binary  granite 
admixture  of  which  they  S'^'f  ""'^  ^"^t  ^  transition  from 
■        Z  pegmatite.     There  is  *»^ J'^  J7„„e  essentially  pyr- 

pje  quarts  '"  ^  8™"Srbt ring' pa«e,  ««*  ofitse^ 
oxenic,  each  occasionally  bea""8  J^  ^,,  associated  m  the 
also  forms  rock-masses,    .f  \°"^ti       bands  or  irregular 
larger  veins,  sometimes  ^^  »^^<=™  Vckness,  but  at  other 
lenticular  masses  a  few  'n*^  "  j^^j  each.     A  frequent 

times  attaining  toea**»  «*.  "^e  vri"^'""^^  °°"'"'vf 
intermediate  type  of  '-'*  m  toe      _      ^^^^^^ 


VI.] 


OF  CKYSTALLINE  EC      IS. 


227 


li 


ill  color,  but  occasionally  bluish,  and  with  cleavage- 
planes  an  inch  in  breadth.  The  quartz  and  feldspar  in 
this  aggregate  sometimes  predominate,  offering  a  transi- 
tion into  the  granitic  rock  already  noticed,  which  fre- 
quently includes  crystals  of  pyroxene,  apple-green  or  grass- 
green  in  color,  and  then  sometimes  holds  clove-brown 
titanite,  brown  tourmaline,  and,  more  rarely,  zircon. 

§  49.  These  rocks,  essentially  made  up  of  feldspar, 
quartz,  and  pyroxene,  were  long  since  noticed  by  the 
writer  as  occurring  among  the  Laurentian  gneisses  in  the 
Rideau  district,  and  at  various  points  in  the  province  of 
Quebec,  and  were  described  in  1866  as  generally  "  grani- 
toid or  gneissoid  in  structure,  sometimes  fine-grained,  and 
at  other  times  made  up  of  crystalline  elements  from  two 
tenths  to  five  tenths  of  an  inch  in  diameter.  .  .  .  They 
are  often  interstratified  with  beds  of  granitoid  orthoclase 
gneiss,  into  which  the  quartzo-feldspathic  pyroxenites 
pass  by  a  gradual  disappearance  of  the  pyroxene."  The 
occasional  presence  in  them  not  only  of  titanite,  but  of 
mica,  amphibole,  epidote,  magnetite,  and  graphite,  was 
then  noticed,  and  attention  was  called  to  the  fact  that 
these  mineral  species  are  common  to  the  pyroxenite  rocks 
and  to  associated  crystalline  limestones.  The  feldspar  of 
these  intermediate  rocks  was  described  as  having  gener- 
ally the  characters  of  orthoclase,  as  was  shown  by  the  anal- 
ysis of  a  specimen  from  Chatham,  Quebec,  but  as  in  some 
cases  triclinic  and  resembling  oligoclase.*  Dr.  Harring- 
ton has  since  found  for  one  of  these  the  composition  of 
albite. 

As  will  appear  from  the  language  just  cited,  these 
aggregates  were  then  regarded  as  portions  of  the  country- 
rock.  The  pyroxenite  seen  in  North  Burgess,  in  the 
Rideau  district,  was  described  as  sometimes  granitoid  and 
at  other  times  micaceous  and  schistose,  interstratified  Avith 
what  was  then  called  a  binary  granitoid  gneiss,  and  also 

*  Geology  of  Canada,  1803,  p.  475;  also  Report  Geol.  Survey  of  Can- 
ada, 1S63-66,  pp.  185  and  224-228. 


'  'l 


r . 


*. 


! 


H 


li!  ;i 


THE  GENETIO  HISTOllY 


[VI. 


228  ,  ^gj^^  holdirg 

one  case  ^o^^^^^TSl  tUe  strike,  and  was  m  p.its 
hundred  and  fifty  leet  w  ,  ,      •„ 

two  feet  in  thicV.ness.  ^    ^^  i^  crystals,  m 

§50    While  apatite  f  ^%f  ^^^  Ji^  the  caleareous  and 

scapolite,  Py^^"^     .       of  these  secondaiy  '^*'l.  i^-)  ^yas 

*"  venous  oha.  c^er  o^  ^,^  ^ 3  tot  it 

also  intersect  the  rea  ^^^^.^  ^  i^t^r  pe"0  ^ 

became  "Wf  "  .....ifom  mass««  m     .  jlo-iting  these 

*°  *^  Ca    ^  ftt  that  the  P-«-\t:io  Ss.  and 
were  enclosed ,  in  repeated  m  *«»«  ,       ^1,^0  the 

mineral  »pec>es  had  bee        l^.^.^  ^^^^^_  „„t  fess  tha 

that  the  Py'«r  .,to"  e  masses,  were  portions        g 
toterstratified  l"»;*"^i„aes.«  .         .,,,  found 

-trrtXHtrgeoiti^M-y^^^^^^^ 

who,  m  184^'    \^iune  rocks  m  northern  i         •  ^j^^^es, 

origin,  a  view  which  ^vas       P^^^^^^  ^iX  and 

Ltio  relations  ot  tne  v^^  Leonhard,  bavi,  ^i 

gnostic  reia  ^^j  yon  i^«  of  certain 

^^^rLC::t  tau^;- ;^-trr^.V  Bana, 

«  For  an  ai^alysis  01         ^nd  CUem.  and  (.eoi. 
Jour.  Science,  187^  !"•» 


VI.] 


OF  CRYSTALLINE  ROCKS. 


229 


n. 
d 
re 
3d 

)m 

,se, 

lUe 

lich 

was 

,t  it 

ided 

^■euis 

:bese 

and 
the 

great 


[\ 


ir 


found 
inions, 
ers  oi 
)rk,  i-e- 
)U-ores, 

utonio 
nt  geo- 

was  in 
ivi,  and 
£  certain 

).  Dana, 

see  Ainer. 


who  supposed  that  some  of  the  so-called  primary  lime- 
stones "  were  of  Igneous  origin,  like  granite."  The  aque- 
ous origin  of  similar  calcareous  masses  in  Scandinavia 
had,  however,  been  recognized  by  Scheerer  and  by  Dau- 
br^e,  and  in  Germany  by  Bischof,  while  the  vein-like 
character  of  certain  aggregates  of  this  kind  in  which 
various  silicates  and  other  mineral  species  arc  associated 
with  carbonate  of  lime,  in  the  ancient  gneisses  of  North 
America,  had  been  noticed  by  C.  U.  Shepard,  H.  D. 
Rogers,  and  W.  P.  Blake,  among  others,  as  was  shown  by 
the  writer  in  some  detail,  in  1866.  In  a  paper  then  read 
before  the  American  Association  for  the  Advancement  of 
Science,  it  was  said  that  deposits  of  carbonate  of  lime, 
sometimes  of  great  dimensions,  and  holding  the  charac- 
teristic minerals  of  the  crystalline  limestones,  are  found 
filling  fissures  and  veins  in  the  Laurentian  gneisses. 
These  were  then  designated  endogenous  rocks,  regarded 
as  of  aqueous  origin,  and  to  be  carefully  distinguished 
from  intrusive  or  exotic  rocks.* 

The  subject  was  discussed  in  the  same  year  in  an  ac- 
count of  the  mineralogy  of  the  Laurentian  rocks,  when 
it  was  said,  in  commenting  upon  clie  view  of  Emmons 
that  such  masses,  and  in  fact  all  of  the  crystalline  lime- 
stones of  the  series,  are  eruptive  :  —  "  The  greater  part  of 
the  calcareous  rocks  in  the  Laurentian  system  in  North 
America  are  stratified,  and  the  so-called  eru^jtive  lime- 
stones are  really  calcareous  veinstones  or  endogenous 
rocks,  generally  including  foreign  minerals,  such  as  pyrox- 
ene, scapolite,  orthoclase,  quartz,  etG."t  I  had  not  at  that 
time  as  yet  discovered  that  these  same  endogenous  masses 
may  include,  besides  calcareous  bands,  others  essentially 
quartzose,  pyroxenic,  and  feldspathic,  resembling  more  or 
less  the  strata  of  the  enclosing  gneissic  series,  nor  con- 

*  Proc.  Amer.  Assoc.  Adv,  Science,  1806,  p.  54;  also  Can,  Naturalisi 
(IL),  iii.,  123. 

t  Report  Geol.  Survey  of  Canada,  18(5.3-66,  p.  194.  See  also  the  facts 
resumed  in  Chem.  and  Geol.  Essays,  p.  218. 


il 


i    qm 


i  i 


:!; 


!fe- 


H 


I ' 


II 


1 


THE  GENETIC  HISTORY 


IVI. 


^^^  ***  iv.nds  mii'l^t  sometimes 

,  ^    T    d  Burbank  a 

L  u  rentian  type,  to  whie  - 1  ^^^  '^^,„i„„a  tke  enJogenous 

„t  iutevvals  for  twenty-iivo  mi     ,  j  ^^^;^^i  the 

Box'o,-c„gU,  and  f '™;,'';  t  'luestion  of  tUe»e  vem- 
attention  of  Mr.  Buvbank    o        _^^1  p„t,Ucatio„3  0U866. 

like  masses.  l^^^^«^^^^  „tee»atio„s,  UaO,  -  ^f ;  ^ 
He,  as  a  result  ot  laiia«  Umestonea  of   the  le^i 

"tded  himself  "-' f  "^J  ,g''  „„ks,  not  erupt.ve,  b« 
were  newer  than  the  <^f  ^",f  "f       „i„g  fissures  in    the 
■       :7  a  vein-like   ctaacter      -""l^y^/uong,  in  oer  ani 
g,e-,ss,  of  wluoh  charac         ^J\„e  tended  str«ct«e 
rases,  Ki-.e  evidence.!    ""."^.rious  enclosed  mmeials, 
vi  b  ein  the  arrangement  of  the  vano      ^^^^,^^  ,^^,,to.o. 
iLa  described  them  111 IBH""'  ,  ;on  under 

Inisiu  Canada,  and  enumera  ed  »  ^^«,  J(,„,terite 

ov  so-called  boWomte),  pWog  P      .^  .^^,^g,,,„  ^nds  01 
Wsides  serpentine   m  g'*'"\"      .^^  „£  chrysotile.    I0 

titanite.  t  B  Perry  at  the  same  time  and  itocej 

iottel""-lf"o!aui.to-^^^^^^^ 


^ii!    i 


iL 


VI.] 


OF  CRYSTALLINK  ROCKS. 


231 


New  York,  though  possessing  "  the  form  of  dikes,"  "  have 
a  vein-like  structure,  and  sliould  be  regarded  us  true  vein 
stones."  He  farther  says  of  these  deposits:  "The  foliated 
structure,  with  its  accompanying  series  of  mineral  sub- 
stances, each  occurring  in  a  determinate  order,  evinces 
tliat  the  process  of  deposition  was  gradual  and  probably 
long  continued."  Thus  these  observers,  in  1871,  had, 
although  without  acknowledgment,  confirmed  my  obser- 
vations, and  adopted  my  conclusions  of  1866,  as  to  these 
endogenous  calcareous  masses  of  the  ancient  gneissic 
series.  J.  W.  Dawson  had  in  1869  recognized  Eozolin 
Canaihnse  in  a  serpentinic  limestone  from  Chelmsford, 
and  both  Burbank  and  Perry  maintained  thai  all  of  the 
limestone  nuisses  of  the  region  were  veinstones,  as  an 
argument  against  the  organic  nature  of  Eozoon. 

§  54.  The  mineralogy  of  these  endogenous,  more  or 
less  calcareous  masses,  has  been  the  subject  of  much 
study.  While  sometimes  having  the  aspect  of  a  coarsely 
crystalline  limestone,  and  nearly  pure,  they  may  include 
apatite,  fluorite,  chondrodite,  wollastonite,  amphibole, 
pyroxene,  danburite,  serpentine,  phlogopite,  gieseckite, 
orthoclase,  scapolites,  brown  tourmaline,  idocrase,  epi- 
dote,  allanite,  garnet  (sometimes  ehromiferous),  titanite, 
zircon,  rutile,  spinel,  volcknerite,  corundum,  menaccanite, 
magnetite,  hematite,  pyrite,  and,  more  rarely,  pyrrhotite, 
chalcopyrite,  sphalerite,  molybdenite,  and  galenite.  To 
these  must  be  added  prehnite,  stilbite,  chabazite,  and  ba- 
rite.  All  of  these  species  have  been  met  with  in  the 
deposits  studied  in  Canada  and  New  York,  while  in  the 
similar  calcareous  masses  in  eastern  Massachusetts  chrys- 
olite and  petalite  occur.  Exceptionally,  as  in  Frank- 
lin and  Stirling,  New  Jersey,  there  are  found  in  this 
connection  zinciferous  and  manganiferous  minerals,  as 
willemite,  tephroite,  spartalite  and  franklinite.* 

*  For  farther  and  more  detailed  accounts  of  the  occurrence  of  the 
mineral  species  already  mentioned,  and  many  others  which  are  found 
with  the  calcareous  masses  of  the  Laurentian  rocks,  see  Report  Geol. 


232 


THE  GENETIC   HISTORY 


[VI. 


id; 


■I-  f 


■; }( 


|i) 


The  various  associations  of  apatite  in  those  aggregates 
are  wortliy  of  notice.  Crystals  of  this  species  have  been 
observed  by  the  writer  directly  inii)e(lded  in  the  <[uartzo- 
feldspathic  veinstone,  in  vitreous  (|uartz,  in  calcite  and 
dolomite,  in  pyroxene,  in  crystals  of  phlogoi)ite,  in  pyrite, 
in  magnetite,  in  H[)inel,  and  in  foliated  gra[)hite,  as  well  as 
in  a  massive  granular  apatite,  which  sometimes  surrounds 
large  and  well  delined  crystals  of  the  same  species.  Dr. 
Harrington  has  farther  noted  its  inclusion  in  ami)hibole, 
in  orthoclase,  in  sca[)olite,  in  steatite,  and  in  lluorito.  On 
the  other  hand,  apatite  crystals  have  been  found  to  enclose 
quartz,  calcite,  fluorite,  phlogopite,  i)3'roxcne,  zircon, 
titanite,  and  pyrite.  The  apatite  of  these  dei)()sits,  so  far 
as  known,  is  essentially  a  fluor-ai)atite,  containing  in  one 
case,  by  the  writer's  analysis,  0.5  hundredths  of  chlorine. 
From  these  facts  it  is  evident  that  the  succession  t)f  species 
in  these  veins  is  by  no  means  invariable.  Mention  should 
here  be  made  of  the  apatite  occurr.iig  in  disseminated 
grains  in  the  great  deposit  of  magnetite  so  extensively 
mined  at  Mount  Moriah,  New  York.  TiiC  banded  arrange- 
ment of  the  crystalline  apatite,  generally  reddish  in  color 
and,  in  thin  layers,  occasionally  predominating,  gives  a 
stratified  aspect  to  the  iron  ore.  A  similar  aggregate  is 
found  in  the  llideau  district,  in  Ontario. 

§  55.  The  stratiform  character  of  these  endogenous 
deposits,  as  seen  alike  in  the  individual  portions,  and  in 
the  arrangement  of  these  as  constituent  parts  of  a  vein, 
is  well  shown  at  the  Union  mine,  in  the  Lievres  district. 
Here  the  great  mass  or  lode  is  seen  to  be  bounded  on  tlie 
west  by  a  dark-colored  amphibolic  gneiss,  nearly  vertical 
in  attitude,  and  with  a  northwest  strike.  Within  the  vein, 
and  near  its  western  border,  is  enclosed  a  fragment  of  the 


Survey  of  Ca  .ada,  1863-66,  pp.  181-229,  which  was  reprinted,  with  the 
exception  of  tlie  last  six  pages,  in  the  Report  of  the  Regents  of  the  Uni- 
versity of  New  Yorlc,  for  1807,  Appendix  E.  See  also,  in  abstract,  Chem. 
and  Geol,  Essays,  pp.  208-217,  and  farther  the  reports  of  Dr.  Harrington 
and  Mr.  J.  Fraser  Torrance,,  cited  on  page  224. 


I-  I 


VI.] 


OF  CRYaXALLINE   ROCKS. 


283 


gneiss,  about  twenty  feet  in  width,  wliich  is  traced  some 
yards  along  the  strike  of  tlio  vein,  to  a  cliff,  where  it  is 
lost  from  sight,  its  breadth  being  previously  nmch  diniin- 
ished.  It  is  a  sliari)ly  broken  mass  of  gray  banded  gneiss, 
with  a  re-entering  angle,  and  its  close  contact  with  the 
surnnuiding  and  adherent  coarsely  granular  pyroxenio 
veinstone  is  very  distinct.  Smaller  masses  of  the  same 
gneiss  are  also  seen  in  the  vein,  which  was  observed  for 
a  breadth  of  about  150  feet  across  its  strike,  —  nearly 
coincident  with  that  of  the  adjacent  gneiss, — and  be- 
yond was  limited  to  the  northeast  by  a  considerable 
breadth  of  the  same  country-rock. 

§  5G.  In  one  oi)ening  on  this  lode  there  are  seen,  in  a 
section  of  forty  feet  of  the  banded  veinstone,  repeated 
layers  of  apatite,  pyroxenite,  and  a  granitoid  quartzo- 
feldspathic  rock,  including  portiojis  of  dark  brown  foli- 
ated pynjxene,  all  three  of  these  being  unlike  anything  in 
the  enclosing  gneiss,  but  so  distinctly  banded  as  to  be 
readily  taken  for  country-rock  by  those  not  apprised  of  the 
venous  character  of  the  mass.  A  fracture,  with  a  latcal 
displacement  of  two  or  three  feet,  is  occupied  by  a  gran- 
itic vein  twelve  inches  wide,  made  up  of  quartz  with  two 
feldspars  and  black  amphibole,  which  themselves  present 
a  distinctly  banded  arrangement.  This  same  granitic  vein 
is  traced  for  fifty  feet,  cutting  obliquely  across  both  the 
pyroxenite  and  the  older  granitoid  rock,  and  at  length 
spreads  out,  ond  is  confounded  with  a  granitic  mass 
interbedded  in  the  greater  vein.  It  is  thus  posterior 
alike  to  the  older  quartzo-feldspathic  rock,  the  pyroxenite, 
and  the  apatite,  —  as  are  uiso  many  smaller  quartzo-feld- 
spathic veins,  which,  both  here  and  in  other  localities  in 
this  region,  intersect  at  various  angles  the  apatite,  the 
pyroxenite,  and  the  granitoid  rock  into  which  the  latter 
graduates.  We  have  thus  included  in  these  great  apatite- 
bearing  lodes,  quartzo-feldspathic  rocks  of  at  least  two 
ages,  both  younger  than  the  enclosing  gneiss.  A  small 
vertical  vein  of  fine-grained  black  diabase-like  rock  inter- 


B    .< 


''ISM 


M-r  - 


;:«.,  iji 


234 


THE  GENETIC  HISTORY 


pn. 


sects  the  whole.  No  one  looking  for  the  first  time  at  this 
section  of  forty  feet,  as  exposed  in  the  quarry,  with  its 
distinctly  banded  and  alternating  layers  of  pyroxenite 
and  granitoid  quartzo-feldspathic  rock,  including  two 
larger  and  several  smaller  layers  of  crystalline  apatite, 
would  question  the  stratiform  character  of  the  mass, 
whose  venous  and  endogenous  nature  is,  nevertheless,  dis- 
tinctly apparent  on  farther  study. 

In  other  portions  of  the  same  great  vein,  which  has 
been  quarried  at  many  points,  this  regularity  of  arrange- 
ment is  lc33  evident.  Occasionally  masses  are  met  with 
presenting  a  concretionar}"-  structure,  and  consisting  of 
rounded  or  oval  aggregates  of  orthoclase  and  quartz,  with 
small  crystals  of  pyroxene  around  and  between  them; 
the  arrangement  of  the  elements  presenting  a  radiated 
and  zone-like  structure,  and  recalling  the  orbicular  diorite 
of  Corsica.  The  diameter  of  these  granitic  concretions 
varies  from  half  an  inch  to  one  and  two  inches,  and  they 
have  been  seen  in  several  localities  in  the  veins  of  this 
region,  over  areas  of  many  square  feet. 

§  57.  In  the  Emerald  mine  the  stratiform  arrange- 
ment in  the  vein  is  remarkably  displayed.  Here,  in  the 
midst  of  a  great  breadth  of  apatite,  were  seen  two  parallel 
bands  (since  removed  in  mining)  of  pyroxenic  rock,  sev- 
eral yards  in  length,  running  with  the  strike  of  the  vein, 
and  in  their  broadest  parts  three  and  eight  feet  wide  re- 
spectively, but  becoming  attenuated  at  either  end,  and  dis- 
appearing, one  after  the  other,  in  length,  as  they  did  also 
in  deptl).  These  included  vertical  layers,  evidently  of 
contemporaneous  origin  with  the  enclosing  apatite,  were 
themselves  banded  with  green  and  white  from  alternations 
of  pyroxene  and  of  feldspar  with  quartz.  Accompanying 
the  apatite  in  this  mine  are  also  bands  and  irregular 
masses  of  ilesh-red  calcite,  sometimes  two  or  three  feet  in 
breadth,  including  crystals  of  apatite,  and  others  of  dark 
green  {imphibole.  Elsewhere,  as  at  the  High  Rock  mine, 
tremolite  is  met  with.    In  portions  of  the  vein  at  the 


u 


ar 


no 


OF  CRYSTALLINE  ROCKS. 


235 


Emer  i.ld  mine  pyrite  is  found  in  considerable  quantity, 
and  occasionally  forms  layers  many  inches  in  thickness. 
Several  large  parallel  bands  of  apatite  occur  here,  with 
intervening  layers  of  pyroxenic  and  feldspathic  rock, 
across  a  breadth  of  at  least  250  feet  of  veinstone,  besides 
numerous  small,  irregular,  lenticular  masses  of  apatite. 
TliG  pyroxenite  in  this  lode,  as  elsewhere,  includes  in 
places  large  crystals  of  phlogopite,  and  also  presents  in 
drusy  cavities  crystals  of  a  scapolite,  and  occasionally 
small,  brilliant  crystals  of  colorless  chabazite,  which  are 
implanted  on  quartz. 

At  the  Little  Rapids  mine,  not  far  from  the  last,  where 
well  defined  bands  or  layers  of  apatite,  often  eight  or  tei. 
feet  wide,  have  been  followed  for  considerable  distances 
along  the  strike,  and  in  one  place  to  about  200  feet  in 
depth,  these  are,  nevertheless,  seen  to  be  subordinate  to 
one  great  vein,  similar  in  composition  to  those  just  de- 
scribed, and  including  bands  of  granular  quartz.  In  some 
portions  of  this  lode  the  alternations  of  granular  pyrox- 
enite, quartzite,  and  a  quartzo-feldspathic  rock,  with  little 
lenticular  masses  of  apatite,  are  repeated  two  or  three 
times  in  a  breadth  of  twelve  inches. 

§  58.  The  whole  of  the  observations  thus  set  forth  in 
detail  above  serve  to  show  the  existence  in  the  midst 
of  a  more  ancient  gneissic  series,  of  great  deposits,  strati- 
form in  character,  complex  and  varied  in  composition, 
and,  though  distinct  therefrom,  lithologically  somewhat 
similar  to  the  enclosing  gneiss.  Their  relation  to  the 
latter,  however,  as  shown  by  the  outlines  at  the  surfaces 
of  contact,  by  the  included  masses  of  the  wall-rock,  the 
alternations  of  unlike  mineral  aggregates,  the  evidences 
of  successive  and  alternate  deposition  of  mineral  species, 
and  the  occasional  unfilled  cavities  lined  with  crystals, 
forbid  us  to  entertain  the  notion,  that  they  have  been 
filled  by  igneous  injection,  as  conceived  by  plutonists, 
and  lead  to  the  conclusion  that  they  have  been  gradually 
deposited  from  aqueous  solutions.     This  conclusion  is 


236 


THE  GENETIC  HISTORY 


fFh 


»  ■ 


^ 


\i 


5) 


made  more  apparent  when  we  compare  these  immense 
banded  lodes  with  the  many  small  veins  from  a  foot  in 
breadth  upwards,  also  banded,  and  lithologically  similar 
to  the  great  lodes,  which  intersect  not  only  these  but  the 
ancient  gneisses,  as  already  described  at  the  High  Rock 
mine,  and  also  in  many  other  localities,  especiuliy  in  parts 
of  the  Rideau  district. 

It  may  here  be  noticed  that  the  very  similar  banded 
and  vein-like  deposits  now  largely  mined  for  apatite  in 
Norway,  are  regarded  by  Brogger  and  Reusch,  who  have 
lately  studied  them,  as  igneous  masses  erupted  in  a  liquid 
condition,  and  slowly  cooled  from  fusion,  a  hypothesis 
by  which  they  e.ideavor  to  explain  many  of  the  phe- 
nomena of  these  deposits.  For  an  analysis  of  their  argu- 
ment and  a  forcible  siateraent  of  the  objections  thereto, 
the  reader  may  consult  Dr.  Harrington's  report  on  the 
apatite  region  of  the  Lidvres.* 

§  59.  These  various  endogenous  deposits  are  instruc- 
tive illustrations  of  the  creuitic  process.  The  alterna- 
tions of  stratiform  layers  of  quartz,  of  calcite,  and  of  feld- 
spathic  and  pyroxenic  aggregates,  with  included  layers  of 
apatite,  pyrite,  etc.,  show  that  a  process  closely  analogous 
to  that  which  formed  the  older  gneissic  series  was  in  ope- 
ration and  gave  rise  to  these  banded  mineral  masses  in  Cue 
midst  of  rifted  and  broken  strata  of  the  Ider  rocks  after 
these  had  assumed  their  present  attitude.  .  The  lithologi- 
cal  resemblances  between  the  older  and  the  younger  de- 
posits are  not  less  remarkable  than  their  differences,  and 
suffice  to  show  the  great  similarity  between  the  conditions 
which  produced  the  veinstones  and  their  enclosing  rocks. 
The  latter,  however,  appear,  in  the  present  state  of  our 
knowledge,  to  have  been  deposited  not  only  on  a  vaster  scale, 
but  apparently  in  a  horizontal  or  nearly  horizontal  attitude. 

§  60.  What  are  regarded  as  examples  of  calcareous  de- 
posits of  the  two  ages  were  described  by  the  writer,  in 

*  Brogger  and  Reusch  ;  Zeitschrift  d.  deutsch.  Geol.  Gesell.  Heft  III., 
pp.  64G-702.     Report  Geol.  Survey  Canada,  1877-78,  G.,  pp.  11-12. 


VI.] 


OF  CRYSTALLINE  ROOKS. 


237 


1878,  as  occurring  at  Port  Henry,  on  Lake  Champlain,  in 
the  State  of  New  York.  Near  the  town  is  a  quarry  whence 
limestone  has  been  got  for  the  blast-furnaces  of  the  local- 
ity. "  Here  elongated,  irregular  fragments  of  dark  horn- 
blendic  gneiss,  from  two  inches  to  a  foot  in  thickness, 
were  found  completely  enveloped  in  crystalline  carbonate 
of  lime.  In  1877,  five  such  masses  of  gneiss  were  exposed 
in  an  area  of  a  few  square  yards.  One  of  these,  a  thin 
plate  of  the  gneiss,  having  been  broken  in  two,  the  enclos- 
ing calcareous  matter  had  filled  the  little  crevice,  keeping 
the  fragments  very  nearly  in  their  place.  The  carbonate 
of  lime,  which  is  coarsely  granular,  and  contains  some 
graphite  and  pyrite,  is  banded  with  lighter  and  darker 
shades  of  color,  and  one  of  its  layers  was  marked  by  the 
presence  of  crystals  of  green  pyroxene  and  of  brown 
sphene.  The  contact  of  this  mass  with  the  surrounding 
gneiss,  which  is  near  by,  is  concealed.  No  serpentine  was 
found  in  this  limestone,  though  it  abounds  in  a  limestone 
quarried  in  the  vicinity.  About  half  a  mile  to  the  north 
is  still  another  quarry,  opened  in  a  great  and  unknown 
breadth  of  more  finely  granular  and  somewhat  graphitic 
limestone,  which  near  its  border  presents  three  beds  of 
two  or  three  feet  each,  interstratified  with  the  enclosing 
gneiss."  Of  this  it  was  said  that  "it  presents  alterna- 
tions of  lighter  felds].athic  and  darker  hornblendic  beds 
with  others  highly  quartzose,  and  includes  layers  of  a 
sulphurous  magnetite,  which  are,  however,  insignificant 
when  compared  with  the  great  deposit  of  this  ore  mined 
at  Mount  Moriah,  in  the  vicinity." 

§  61.  While  the  great  breadth  of  limestone  interstrati- 
fied with  the  gneiss  was  regarded  as  belonging  to  the 
ancient  series,  it  was  said  of  the  limestone  of  the  first- 
described  quarry  that  it  "  seems  clearly  to  be  a  brecciated 
calcareous  vein  enclosing  fragments  of  the  gneiss  wall- 
rock."  *     Reference  was  then  made  to  similar  observations 

*  Azoic  Rocks,  etc.,  pp.  166-167;  also  The  Geology  of  Port  Henry, 
Canadian  Naturalist,  X. ,  No.  7. 


iNIJ!  i: 


I'*  Ij.' 


I 


238 


THE  GENETIC  HISa?ORY 


[VI. 


in  this  vicinity,  described  by  Prof.  James  Ifal.  n\  1876, 
who,  from  this  breccia  of  gneiss-fragments  in  an  exposure 
to  crystalline  limestone,  rightly  inferred  thf;  posterior  de- 
position of  the  latter,  and  was  led  to  co^^-jecture  that  it 
might  belong  to  a  newer  geological  series.  The  only 
evidence  of  this,  however,  was  the  enclosed  fragments  of 
the  gneiss,  which,  in  similar  cases,  had  led  Emmons  and 
Mather  to  infer  the  eruptive  character  of  these  same 
limestones,  regarded  by  the  writer  as  endogenous  masses 
or  veinstones.  The  great  thickness  of  the  interstratified 
limestone-masses  which  form,  according  to  Logan,  integral 
parts  of  the  vast  Laurentian  series,  and  their  geographi- 
cal extent,  were  described  in  detail  in  the  publications  of 
the  geological  survey  of  Canada,  in  1863,  and  farther  in 
1866.  A  summary  of  these  results  will  be  found  in  the 
writer's  volum'i  on  Azoic  Rocks,*  and  farther  on  in  Essay 
IX.  of  this  volume. 

§  62.  As  regards  the  genesis,  according  to  the  crenitic 
hypothesis,  of  the  various^  mineral  species  found  in  this 
vast  crystalline  series,  alike  in  the  more  ancient  strata  and 
in  their  included  endogenous  masses,  we  have  already 
considered  the  formation  of  the  double  silicates  of  alu- 
mina with  alkalies  and  lime,  represented  by  the  various 
feldspars,  and  more  rarely  by  the  scapoliles,  epidote,  gar- 
net, and  the  muscovitic  or  non-magnesian  micas.  These 
latter,  though  abundant,  with  garnet  and  black  tourmaline, 
in  some  granitic  veins  in  this  geological  series,  are  rare  in 
those  portions  in  which  the  protoxyd-silicates  abound,  — 
while  the  silicates  of  alumina  without  protoxyd-bases, 
such  as  are  andalusite,  fibrolite,  cyanite,  topaz,  and  pyro- 
phyllite,  are  unknown.  On  the  other  hand,  aluminous 
double  silicates  with  magnesia  are  abundantly  represented 
by  phlogopite,  and  protoxyd-silicates  with  magnesia,  such 
as  chondrodite,  pyroxene,  and  amphibole,  are  abundant; 
the  simple  calcareous  silicate,  wollastonite,  being  more . 
rarely  met  with.     The  genesis  of  all  these  we  have  sup- 

*  Azoic  Rocks,  p.  154. 


vi.] 


OF  CEYSTALLINE  ROCKS. 


239 


posed  to  be  by  the  reaction  of  soluble  calcareous  silicates 
with  magnesiau  and  ferrous  solutions.  The  magnesia 
required  may  be  found  either  in  salts  like  those  of 
sefv-water,  or  in  solutions  of  magnesian  bicarbonate  from 
sub-aerial  decay  of  plutonic  rocks,  which  solutions,  by 
reaction  with  lime-silicates,  would  give  rise  to  insoluble 
magnesian  compounds  and  soluble  lime-carbonate.  A 
similar  reaction,  with  liberation  of  silica,  would  result 
from  the  direct  operation  of  carbonic  dioxyd  upon  the 
lime-silicate.  The  intervention  of  ferrous  solutions  in 
similar  reactions  has  already  been  discussed,  in  consider- 
ing the  origin  of  glauconite,  on  page  197. 

§  63,  As  regards  the  presence  in  these,  and  similar 
crystalline  rocks,  of  basic  oxyds  uncombined  with  silica 
or  with  carbonic  acid,  such  as  alumina  and  magnesia  in 
corundum,  spinel,  and  some  chromites,  chromic  oxyd  in 
the  latter  and  in  some  spinels,  glucina  and  magnesia  in 
chrysoberyl  and  periclase,  together  with  zinc,  manganese 
and  iron-oxyds  in  spartalite,  franklinite,  magnetite,  and 
hematite,  not  to  mention  titanic  oxyd  in  rutile  and  ''n 
menaccanite  and  other  titanates,  it  should  be  noticed  tb  .'; 
tliese  various  compounds,  for  the  most  part,  occur  in  sncu 
intimate  association  with  certain  silicates  as  to  suggest 
their  contempoi'aneous  production  Thus  corundum  and 
spinel  are  found  crystallized  with  certain  micas,  with  chlo- 
rites  or  with  feldspars,  pyroxene  or  chrysolite,  in  which 
latter,  or  in  serpentine,  chromite  is  generally  met  with. 
Spartalite  and  franklinite  are  associated  with  silicates  of 
zinc  and  manganese,  and  magnetite  with  quartz,  with  or- 
thoclase,  with  pyroxene,  with  chondrodite,  or  with  chryso- 
lite, while  rutile  and  menaccanite  are  found  in  like  man- 
ner with  feldspars,  with  phlogopite,  or  with  serpentine. 
The  intimate  association  of  magnetite  with  calcite,  with 
apatite,  with  pyrite,  and  with  graphite,  in  these  deposits, 
may  also  be  noticed.  We  must  conclude  that  all  these 
simple  and  compound  oxyds  have  been  in  solution,  and 
have  crystallized  in  the  presence  of  the  various  silicates, 


H 


I 


"I  I 


K'  i     1, 


Ai 


I  <     in 


,il   "i  ' 


240 


THE  GENETIC   HISTORY 


[VI. 


etc.,  and  in  many  cases  with  quartz.  It  is  evident  that 
the  partial  reduction  and  solution  of  ferrous  oxyd  by  the 
intervention  of  the  products  of  organic  decay,  and  its 
subsequent  precipitation,  which  in  later  times,  has  played 
so  large  a  part  in  the  genesis  of  iron-oxyds  and  carbonate, 
is  not  the  sole  agency.  A  ^u'ocess  which  separates  not 
only  iron-oxyd,  but  chrome-oxyd,  alumina,  glucina,  mag- 
nesia, and  zinc  and  manganese-oxyds,  from  their  silicated 
combinations,  and  has  permitted  them  to  crystallize  side 
by  side  with  silicates,  and  even  with  free  silica,  has  inter- 
vened in  the  genesis  of  these  ancient  crenitic  deposits. 
The  solvent  action  exerted  by  solutions  of  alkaline  sili- 
cates on  oxyds  of  iron,  manganese,  zinc,  magnesium,  and 
calcium,  as  well  as  upon  those  of  tin,  antimony,  copper, 
and  mercury,  throws,  as  elsewhere  pointed  out,  an  impor- 
tant light  on  this  problem  (pages  150,  181). 

To  this  wo  must  add  the  dissociation  of  silicate  of  alu- 
mina at  elevated  temperatures,  under  pressure,  in  presence 
of  alkaline  solutions,  with  separation  of  silica  in  the  form 
of  quartz,  as  observed  both  by  Daubrde  and  Henri  Sainte- 
Claire  Deville  (pages  148,  156).  These  experimenters 
obtained  at  the  same  time  zeolites,  and  one  of  them  pyr- 
oxene, apparently  with  magnetite,  while  Friedel  and  Sar- 
rasin,  under  similar  conditions,  got  orthoclase  and  albite, 
quartz  and  analcite.  We  are  as  yet  ignorant  under  what 
circumstances  the  liberated  alumina  might  be  separated 
from  these  solutions  as  corundum  or  diaspore.  The  con- 
ditions of  temperature,  and  the  presence  of  alkaline  solu- 
tions in  these  experiments,  approach  very  closely  to  those 
which  we  have  supposed  to  concur  in  the  formation  of 
mineral  species  by  the  crenitic  process. 

§  64.  The  geognostic  and  genetic  history  of  the  great 
endogenous  crystalline  masses  which  we  have  now  dis- 
cussed in  some  detail  is  important  for  several  reasons: 
1.  It  brings  before  us  the  views  of  the  plutonists,  who  see 
in  great  bodies  of  crystalline  limestone,  and  of  magnetite, 
as  well  as  in  granitic  veins  and  in  metalliferous  quartz- 


VI.] 


OF  CRYSTALLINE  ROCKS. 


241 


lodes,  the  evidences  of  igneous  eruption.  2.  It  shows  the 
differences,  alike  mineralogic  and  geognostic,  between  true 
exotic  rocks  (which,  with  small  differences  in  composition, 
have  been  erupted  through  widely  separated  geologic 
ages  up  to  the  present)  and  those  endogenous  deposits 
which  are  found  only  in  eozoic  rocks,  and  were  formed  in 
eozoic  time,  since  their  fragments  are  met  with  in  the 
oldest  overlying  paleozoic  sediments.  3.  It  makes  evi- 
dent the  close  mineralogic  resemblances  between  these 
endogenous  crystalline  masses  and  the  more  ancient  en- 
closing rocks,  and  thus  helps  us  to  a  clearer  conception 
of  the  conditions  under  which  these  ancient  gneissic 
strata,  and  the  pre-gneissic  granite  itself,  were  generated. 
§  65.  The  crenitic  hypothesis,  as  we  have  seen,  sup- 
poses that  the  granite,  and  the  succeeding  crystalline 
schists,  have  been  built  up  by  matters  dissolved  from  a 
primary  plutonic  substratum,  upon  which,  as  upon  a  floor, 
through  successive  ages,  was  laid  down  the  enormoas 
thickness  of  crenitic  rocks  which,  with  small  exceptions, 
make  up  the  pre-Cambrian  terranes.  The  bearing  of  this 
hypothesis  upon  the  great  problem  presented  bj-  the  cor- 
rugated condition  of  the  older  crystalline  schists  has 
already  bepu  noticed  on  page  179.  The  contraction  of  a 
cooling  globe,  which  is  often  cited  in  explanation  of  this 
phenomenon,  is  clearly  inadequate  to  account  for  this 
great  and  general  corrugation  of  the  strata,  and  the 
present  writer  in  1860  *  suggested,  as  a  farther  element  in 
explanation  thereof,  the  condensation  during  crystalliza- 
tion of  the  mechanical  sediments  from  which,  in  accord- 
ance with  the  Huttonian  hypothesis,  the  crystalline  schists 
were  supposed  to  be  derived.  This  explanation,  based  on 
an  untenable  hypothesis,  must,  however,  be  rejected. 
The  endoplutonist  must  appeal  to  contraction  in  the  igne- 
ous mass  of  the  globe  as  the  only  explanation  of  the  corru- 
gations of  its  outer  envelope,  while  the  exoplutonist  adds 

*  Amer.  Jour.  Science,  xxx.,  138,  and  Chem.  and  Geol.  Essays,  pp.  56, 
71. 


I:-    M: 


^  liilil^ 


242 


THE  GENETIC  HISTORY 


LVI. 


thereto  the  diminution  of  the  I'quid  interior  as  the  result 
of  successive  transfers  of  portions  of  its  mass  by  ejections 
of  igneous  material  from  beneath  a  first-formed  crust. 
Against  this  latter  c  ^lanati-  i  it  is  to  be  urged  that,  as 
we  have  endeavored  ';;>  sji.  vv,  the  successive  groups  of 
stratiform  crystalline  i'n:kA  v  'ch  have  been  laid  down  on 
the  pre-gneissic  granite,  id  tt^en  this  primeval  granite 
itself,  are  not  igneous  but  aqueo  ..  in  origin,  so  that  the 
exoplutonic  hypothesis  itself  is  untenable.  The  amount 
of  plutonic  extravasation  in  pre-Cambrian  times  was  ap- 
parentl}''  small. 

§  QQ.  The  crenitic  hypothesis,  however,  admits  a  trans- 
fer of  matters  from  below  upwards,  in  a  state  of  solution, 
and  the  building-up  from  them,  upon  the  solid  floor  of 
igneous  rock,  of  the  granite  and  all  the  succeeding  crystal- 
line schists,  as  in  the  scheme  of  the  exoplutonists.  This 
new  aqueous  hypothesis  thus  offers,  it  is  believed,  for  the 
first  time,  a  reasonable  and  tenable  explanation  of  the  uni- 
versal corrugation  of  the  oldest  crystalline  strata.  The 
earth,  according  to  this  hypothesis,  although  intensely 
heated,  had  not,  even  at  the  early  time  when  the  waters 
were  first  condensed  on  its  surface,  a  liquid  interior,  but 
was  solid ;  and  its  crust  is  supposed  to  have  presented  no 
variations  in  composition,  except  such  as  might  result  from 
crystallization  and  eliquation  in  a  purely  igneous  con- 
gealing mass.  The  superficial  quartzo-feldspathic  or  gran- 
itic layer,  which  is  believed  to  overlie  everywhere  the 
quartzless  basic  doleritic  rock,  did  not  then  exist,  but  has 
since  been  derived  by  crenitic  action  from  the  primary 
plutonic  layer.  This  granitic  stratum  is,  however,  itself 
still  subject,  like  the  basic  stratum  beneath,  to  softening 
under  the  combined  influences  of  water  and  heat,  and  to 
extrusion  in  the  forms  of  eruptive  granite  and  trachyte ; 
although  it  is  less  fusible,  and,  consequently,  less  suscep- 
tible of  differentiation  by  eliquation.  It  is,  moreover,  at 
the  same  time,  less  liable  to  alteration  by  lixiviation,  from 
the  fact  that  it  is  not  a  mass  cooled  from  igneous  fusion. 


'1  ii 


VL] 


OF   CRYSTALLINE  ROCKS. 


243 


dno 

from 
con- 

Tran- 
the 

At  bas 
iTiary 
itself 

eiiing 
and  to 
chyte; 
,u3cep- 
jr,  at 
n,  from 
fusion, 


but  one  deposited  from  water  at  comparatively  low  tem- 
peratures, and  thus  lacks  the  porosity  which  belongs  to 
the  original  pluLonic  stratum. 

§  07.  The  upward  transference  of  the  vast  and  un- 
known quantity  of  material  constituting  the  ancient 
granitic  and  gneissic  rocks,  which  are  at  least  many  miles 
in  thickness,  and  the  contraction  of  the  plutonic  substra- 
tum, diminished  by  the  removal  of  this  great  mass,  would 
necessarily  result  in  great  movements  of  subsidence,  with 
plications  and  fractures  of  the  gneissic  strata.  We  are, 
of  course,  ignorant  whether  these  processes  went  on  to  a 
uniform  degree  over  the  whole  surface  of  the  earth,  and 
whether  similar  conditions  of  thickness,  and  similar  corru- 
gations, exist  in  those  great  portions  of  t'le  eozoic  crust 
which  are  concealed  beneath  the  ocean's  waters,  and  be- 
neath accumulations  of  newer  strata.  It  may  well  be  that 
the  plication  of  the  ancient  granitic  crust  was,  as  in  the 
case  of  younger  stratified  rocks,  limited  to  certain  areas. 
It  can  only  be  affirmed,  in  the  present  state  of  our  knowl- 
edge, that  in  the  relatively  very  small  areas  of  the  oldest 
gneissic  rocks  known  to  us,  this  plication  is  great  and 
ai)parently  universal,  diminishing,  however,  materially  in 
degree,  in  the  younger  gneissic  series. 

§  68.  Within  the  fractures  and  rifts  of  the  ancient 
gneissic  strata  resulting  from  these  great  movements,  the 
products  of  the  uninterrupted  crenitic  process  would 
henceforth  be  deposited,  filling  them  with  masses  closely 
resembling  those  of  the  enclosing  strata.  Repetitions  on 
a  smaller  scale  of  these  movements  would  give  rise  to 
newer  fissures  intersecting  alike  these  strata  and  the  first- 
deposited  veinstones,  in  the  manner  shown  in  our  studies 
of  the  Laurentian  rocks,  where  the  process  which  pro- 
duced the  original  quartzose,  feldspathic,  and  calcareous 
deposits  of  the  series  was  repeated  at  least  twice,  giving 
rise  to  primary  and  to  secondary  veinstones  mineralogi- 
cally  very  similar  to  the  first-formed  or  country-rock,  and 
therebv  showiujir  the  survival  of  the  original  chemical  con- 


■i. 


^    ■  m 


mm 


I    M 


'  '■{■  ■■( 


i-m 


^^  Jill    ! 


■li  i 


244 


THE  GENETIC  HISTORY 


[VI. 


ditions  of  solution  and  deposition  after  one,  and  even  after 
two  movemeiits  of  displacement  and  disruption  in  the 
region. 

§  69.  We  have  thus  endeavored  in  the  present  essay  to 
bring  together,  in  the  first  place,  a  number  of  facts  wliich 
serve  to  throw  light  upon  the  generation  of  mineral  sili- 
cates by  aqueous  processes,  especially  in  later  times,  sub- 
sequent to  the  formation  of  the  great  series  of  crystalline 
schists,  and  thereby  help  to  a  better  understanding  of  the 
crenitic  hypothesis.  We  have  next  C(Misidered  the  two 
plutonic  hypotheses  as  to  the  origin  of  crystalline  rocks, 
and  have  discussed  the  question  of  stratiform  structure  in 
rocks  whose  eruptive  character  is  undisputed.  This  has 
led  us  to  consider  the  process  of  differentiation  in  such 
masses  through  partial  crystallization  and  eliquation,  and, 
farther,  to  a  discussion  of  the  possible  relations  of  waior 
to  the  process.  The  secular  changes  which  may  be 
wrought  in  igneous  masses  by  aqueous  percolation  are  next 
discussed,  with  reference  at  the  same  time  to  the  crenitic 
process.  From  this  we  are  led  to  a  discussion  of  the 
stratiform  structure  seen  in  vein-like  masses  for  which  an 
igneous  origin  is  inadmissible,  and  which,  it  is  maintained, 
are  endogenous  deposits  of  crenitic  origin.  An  account 
of  these,  as  they  have  been  observed  in  the  ancient  gneissic 
rocks  of  North  America,  leads  to  a  farther  consideration  of 
the  crenitic  hypothesis,  alike  in  relation  to  the  genesis  of 
the  silicates,  carbonates,  riud  non-silicated  oxides  of  the 
crystalline  rocks,  and  also  to  the  general  plication  of  the 
ancient  crystalline  strata. 

§  70.  The  conclusions  from  this  extended  study  are, 
briefly,  as  follows.  The  quartzless  basic  material  which  is 
supposed  to  have  constituted  the  primary  plutonic  mass, 
and  is  the  direct  source  of  basaltic  and  doleritic  rocks,  has 
been  subject  to  modifications  from  three  agencies :  — 

1.  The  solvent  action  of  permeating  and  circulating 
waters,  which,  from  parts  of  it,  have  removed  alumini,  with 
preponderating  proportions  of  silica  and  potash,  —  the  ele- 


y^ 


OF  CRYSTALLINE  HOCKS. 


245 


I 


of 
the 
tlie 


ating 
with 
lie  ele- 


ments of  granitic,  trachytic,  and  gneissic  rocks, — and 
also  silicates  of  ahunina  and  otlier  protoxyds,  'wliicli  have 
been  more  or  less  directly  the  sourco  of  the  other  silicated 
species,  of  the  oxyds,  and  in  part  also  of  the  carbonates 
of  the  crystalline  schists  and  veinstones  :  — 

2.  The  farther  action  of  the  same  circulating  waters  in 
carrying  down  from  the  surface,  alike  in  the  condition  of 
carbonates,  formed  by  sub-aerial  action,  and  of  sulphates 
and  chlorids,  large  ])ortions  of  calcium,  magnesium,  sodium, 
and  potassium,  —  all  of  which,  by  interchange  and  re- 
placement, have  variously  modified  the  composition  of 
the  plutonic  material :  — 

3.  The  process  of  differentiation  in  portijns  of  the 
plutonic  mass  by  partial  crystallization  and  eliquation, 
thereby  giving  rise  to  more  chrysolitic  and  more  pyroxenic 
aggregates  on  the  one  hand,  and  to  more  feldspathic  aggre- 
gates on  the  other,  —  a  process  in  which  it  is  conceived 
water  may  intervene,  giving  to  the  material  an  igneo- 
aqueons  fluidity.  All  of  these  agencies,  it  is  believed, 
have,  from  the  earlier  ages,  been  at  work  on  the  plutonic 
substratum,  causing  secular  changes  alike  in  the  crenitic 
products  derived  therefrom,  and  in  the  residual  portion, 
from  which  have  come,  and  are  still  derived,  the  basic 
eruptive  rocks. 

^  Appendix. 

The  genesis  of  dense  crystalline  species  in  less  dense  colloidal  fused 
inagraas,  wliether  hydrous  or  anhydrous  (pp.  209,  222),  not  only  involves 
the  disengagement  of  heat,  but,  as  Becker  has  shown  ( Amer.  Jour.  Science, 
xxxi.,  120),  its  disengagement  at  the  maximum  rate,  tiius  maintaining 
the  liquidity  of  the  crystallizing  magma.  The  passage  of  certain  dense 
species,  when  fused  per  se  {post,  pp.  299,  .'^00),  into  vitreous  or  crystalline 
forms  of  less  specific  gravity  is  no  exception  to  the  law  of  condensation, 
since  the  chemical  and  physical  conditions  are  unlike  those  of  the  more 
complex  magma.  When  such  a  magma,  holding  combined  a  portion  of 
water,  is  changed  into  anhydrous  species,  this  will  be  liberated,  as  appears 
in  the  often  observed  disengagement  from  solidifying  lavas  of  aqueous 
vapor,  sometimes  with  boric  oxyd,  fluorhydric  and  chlorhydric  acids,  and 
various  chlorids.  Hence  silicates  like  epidote,  tourmalines,  and  micas, 
which  contain  such  volatile  elements,  will  only  be  generated  imder  con- 
ditions which  prevent  their  liberation. 


VII. 


■J 

! 

^ 

,■1 

1 
1      j 

Jimr 

mm- 


II  i 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 

This  essay,  presentcil  and  read  In  abstract  to  the  National  Academy  of  Sciences 
at  AVashingtun,  April  17,  18M3,  was  publiHhed  under  the  title  of  "  The  Decay  of  Uouks 
Geologically  Considered  "  In  September  of  the  same  year,  In  the  Anierioau  Journal 
Of  Science,  [III.],  Jtxvl.,  190-213. 

§  1.  The  subject  of  the  decay  of  rocks  has  not  yet 
received  from  geologists  all  the  attention  which  it  merits, 
and  there  still  appear  to  be  misconceptions  with  regard  to 
it  which  warrant  us  in  reviewing  some  points  in  its  his- 
tory. F.  II.  Storer,*  in  a  recent  notice  of  a  suggestion  of 
Nordenskiold  as  to  the  liberation  of  gems  thi-ough  the 
decay  of  the  feldspathic  rocks  in  which  they  are  often  con- 
tained, cites  with  approval  the  opinion  of  Professor  Stubbs 
of  Alabama  that  "the  decomposition  of  these  rocks  in 
southern  latitudes  has  proceeded  much  faster  than  with 
the  same  rocks  in  higher  latitudes,"  a  "  condition  which 
can  be  accounted  for,  to  a  large  extent,  by  climatic  influ- 
ences." The  cold  and  frost  now  prevailing  in  northern 
regions  are  supposed  by  him  to  retard  the  action  of  atmos- 
pheric waters,  regarded  as  the  chemical  agent  of  this 
process  of  decay.f  These  views,  implying  that  the  pro- 
cess is  one  belonging  to  the  present  time,  are  accepted  by 
Storer,  who  writes  of  the  "more  active  and  thorough- 
going disintegration  which  occurs"  in  these  southern 
regions. 

§  2.  That  the  presence  in  the  northern  hemisphere  of  a 
mantle  of  softened  material,  from   the  decay  in  situ  of 

•  Science,  for  Feb.  16, 1883,  p.  29. 
t  Bemay's  Hand-book  of  Alabama,  1878,  p.  199. 
246 


of 
no 

t0| 

vie 
as 

sii 

eryl 
foul 
prel 


t. 


Vll.] 


THE   DECAY  OF  CUYSTALLINE  ROCKS. 


247 


of  a 
\tu  of 


crystalline  rocks,  is  more  common  at  the  outcroi)8  of  these 
ill  low  than  ill  high  latitudes,  where  it  is  often  entirely 
absent,  is  a  familiar  fact;  but  it  will,  I  think,  be  made 
evident  that  present  climatic  ditterences  have  nothing  lo 
do  with  the  fact  that  similar  rocks  are  in  one  area  covered 
with  a  thick  layer  of  the  products  of  decay,  and  in  an- 
other are  wholly  destitute  of  it. 

§  3.  The  decay  in  question  is  well  known  to  be  duo  to 
a  chemical  change  of  which  the  predu  inant  mineral  sili- 
cates of  t'"e  rock,  chielly  feldspars  and  amphibole,  are  the 
subjects,  and  which  results  in  the  removal  by  solution  of 
the  protoxyd-bases,  together  with  a  great  proportion  of 
the  combined  silica,  leaving  a  residue  essentially  of  clay, 
mingled  with  quartz,  garnet,  magnetite,  and  such  other 
mineral  species  as  resist  the  process  of  decom[)osition. 

§  4.  A  memoir,  by  Fournet,  published  in  1834,*  gives 
many  facts  regarding  the  early  observations  on  rock-decay. 
Its  author  there  describes  the  wide-spread  decomposition 
of  the  granites  near  Pont-Gibaud  in  Auvergne,  a  change 
which  Ueribier  de  Cheissac  had  already  shown  to  be  an- 
terior to  the  deposition  of  the  tertiary  rocks.  Fournet, 
moreover,  noticed  the  similar  decay  of  basalts,  phonolites, 
trachytes,  and  even  obsidians,  and  described  the  process 
of  exfoliation,  by  which  rounded  masses  of  undecayed 
rock  are  left.  He  cites  in  this  connection  the  observations 
of  Pallas,  who,  in  his  travels  in  Siberia  (17G8-1774), 
noticed  hills  "  that  seemed  composed  of  masses  heajDcd 
together,  as  it  were  rounded  by  decomposition."  The 
view  of  Werner,  that  the  rounded  form  of  masses  such 
as  these  was  due  to  a-iginal  concentric  structure,  was 
rejected  by  Fournet. 

§  5.  In  1818,  Messrs.  J.  F.  and  S.  L.  Dana  dascribed  a 
similar  phenomenon  in  the  decaying  greenstones  at  Sora- 
erville,  near  Boston,  Massachusetts,  where  the  rock  was 
found  to  be  converted  by  deca}'  in  situ  into  nodular  masses 
presenting  exfoliatincr  concentric  laj'ers  of  differing  degrees 

*  Ann.  de  Ch.  et  de  Phys.,  [2],  v.,  225-256. 


k    '  ' 


THE  DECAY  OP  CRYSTALLINE  ROCKS. 


[VII. 


of  decomposition.  These  masses  rest  upon  each  other,  the 
decayed  material  filling  the  interstices.*  In  1825,  J.  W. 
Webster  noticed  the  same  example,  and  explained  the 
formation  of  boulders  by  the  exfoliation  of  the  decayed 
greenstone.!  Again,  in  1858,  W.  P.  Blake  described  the 
production  of  rounded  masses  both  of  sandstone  and  of 
granite  through  disintegration.  He  explains  how  angular 
blocks,  separated  by  joints  admitting  water  to  all  sides, 
would  be  "  attacked  most  i  apidly  on  the  angles,  thus  pro- 
ducing a  succession  of  curved  faces  gradually  approaching 
a  sphere,"  and  illustrates  the  process  by  figures.  He 
described,  moreover,  the  boulder-like  masses  of  granite  in 
Placer  County,  California,  lying  on  an  uneven  surface  of 
the  same  rock,  "  as  due  to  the  manner  in  which  the  rock 
decomposes,  and  not  to  abrasion."  Like  Fournet,  he 
rejects  the  notion  of  an  original  concentric  structure  in 
the  rock.J 

6.  Hartt,  in  1870,  discussed  the  well  known  exam- 
ples of  rock-decay  found  in  Brazil,  and  called  such 
rounded  masses  of  rock  as  we  have  just  described  "  boul- 
ders of  decomposition."  He  moreover  noted  that  the 
process  of  decay  was  there  anterior  to  the  supposi  1  glacial 
action,  which  had  worked  over  the  material  of  the  previ- 
ously decomposed  rocks. §  Lyell  already,  in  1849,  had 
pointed  out  that  the  tertiary  clays  and  sands  of  the 
southern  United  States  have  been  derived  from  the  waste 
of  the  previously  decayed  crystalline  rocks  of  the  region ;  || 
and,  as  we  have  seen,  the  ante-tertiary  dge  of  the  decay  in 
Auvergne  had  long  before  been  recognized. 

§  7.  The  account  given  by  Charles  Upham  Shepard,  in 
1837,  of  the  origin  and  mode  of  occurrence  of  the  porce- 
lain-clays of  western  Connecticut  is  remarkable  for  its 
exactness  and  perspicuity.     That  at  New  Milford  is  de- 

•  Mem,  Amer.  Acad.  Sciences,  1st  Series,  iv.,  201. 

t  Boston  Jour.  Philos.  and  Arts,  ii.,  285. 

t  Geol.  Recon.  of  California,  pp.  146,  286. 

§  Scientific  Results  of  a  .Journey  in  Brazil,  pp.  28,  573. 

II  ijyell,  A  Second  Visit  to  the  United  States,  ii.,  28. ' 


of  til 


« 
t 
t 


»♦ 


Ill 

in 
L'ce- 
its 
de- 


vil.] 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


249 


scribed  as  occurring  "  upon  the  western  slope  of  an  ele- 
vated range  of  granitic  gneiss.  ...  In  many  places  the 
decomposition  of  the  parent  rock  is  so  complete  as  to 
present  the  aspect  of  n  secondary  deposit ;  but  the  pre- 
vailing appearance  is  that  of  the  rock  altered  in  place 
through  the  decay  of  the  feldspar  and  mica.  Indeed,  the 
same  relative  arrangement  of  the  quartz  and  the  altered 
feldspar  is  observed  in  the  bed  as  is  presented  by  these 
materials  in  the  undecomposed  rock.  Veins  and  seams  of 
a  perfectly  impalpable  white  clay  traverse  the  rock  in 
various  directions,  analogous  to  the  veins  of  feldspar  in 
the  granite  of  tlie  neighborhood."  Of  a  pure  white  clay 
in  the  town  of  Kent,  our  author  says,  "  It  forms  a  vein 
many  feet  in  width,  cutting  through  quartz  rock.  It  owes 
its  origin  to  a  graphic  granite,  which  must  have  been  free 
from  mica."  A  similar  vein  of  clay  is  described  as  occur- 
ring in  the  town  of  Cornwall,  and  as  including  frequent 
crystals  of  black  tourmaline ;  the  feldspar  also  being 
incompletely  decomposed.* 

§  8.  As  showing  that  the  process  of  sub-aerial  decay  is 
not  confined  to  silicated  rocks,  it  may  be  noted  that  J.  D. 
Whitney  described,  in  1862,  the  existence,  in  the  lead- 
region  of  Wisconsin,  of  a  layer  of  red  clay  and  sand, 
mixed  with  chert,  sometimes  thirty  feet  in  thickness, 
which  lie  showed  to  be  a  reriduum  from  the  secular  decay 
of  several  hundred  feet  of  the  impure  paleozoic  lime- 
stones of  the  region. f  A  like  occurrence  was  afterwards, 
in  1873,  described  by  Pumpelly,  in  southern  Missouri, 
where  such  residuary  deposits  sometimes  attain  a  thick- 
ness of  120  feet.J  This  process  is  evidently  due  to  a 
simple  solution  of  the  carbonates  of  lime  and  magnesia  in 
meteoric  waters. 

§  9.  A  similar  decay  is  conspicuous  along  the  outcrop 
of  the  Taconian  limestones  and  their  associated  schists  in 

*  Shepard  :  Geological  Survey  of  Connecticut  ( 1837),  pp.  73-75. 

t  Geology  of  Wisconsin,  i.,  121. 

t  Geological  Survey  of  Missouri :  Iron  Ores  and  Coal  Fields,  p.  8. 


WU^mmt 


mmm:<^'^::v 


V'r 


'. :  ■'  i : 


n 


■  I '' 


II    Ml 


250 


THE  DECAx'  OF  CRYSTALLINE  ROCKS. 


[vn. 


the  Appalachian  valley,  as  will  be  noticed  farther  on,  in 
§  25,  and  may  also  be  seen  at  several  points  in  the  Tren- 
ton limestone  and  the  Utica  shale  of  the  St.  Lawrence 
valley.  One  of  these  localities,  described  by  J.  W.  Daw- 
son, is  at  Les  Eboulemens,  on  the  north  shore  of  the  St. 
Lawrence,  below  Quebec.  Here,  at  the  southwest  base  of 
the  liigh  Laurentide  hills,  the  post-pliocene  clays,  enclos- 
ing marine  shells  and  large  gneiss  boulders,  are  found 
resting  upon  a  mass  of  Utica  shale,  deprived  of  its  calcare- 
ous matter,  and  so  soft  as  to  be  readily  mistaken  for  the 
newer  clays  of  the  region,  but  for  its  stratification  and  its 
organic  remains.  This,  according  to  Dawson,  had  been 
changed  to  a  great  depth  by  sub-aerial  action  previous  to 
the  period  of  submcigence,  during  wbich  it  was  covered 
with  the  boulder-clay.*  Some  facts  connected  with  the 
decav  of  the  Trenton  limcsi  iie  near  Montreal  will  be 
mentioned  in  §  40. 

§  10.  It  may  be  said  that,  with  the  exception  of  Dar- 
win, who  had  observed  the  decay  of  rocks  in  Brazil,  and 
conjectured  that  the  process  might  have  been  submarine, 
all  observers  have  correctly  regarded  it  as  sub-aerial.  The 
chemistry  of  the  process  was  discussed,  among  others,  by 
Fournet,  in  the  paper  already  cited,  and  later  by  Delesse, 
in  1858 ;  t  also  very  fully  by  Ebelmen,  who  considered 
the  question  of  rock-decay  in  its  relations  to  the  atmos- 
phere, in  two  memoirs,  in  1845  and  18474  The  same  sub- 
ject was  further  considered  at  some  length  by  the  present 
writer,  in  1880.§ 

§  11.  Having  thus  briefly  indicated  some  of  the  points 
in  its  h  tory  during  the  past  century,  we  are  prepared  to 
notice  in  more  detail  the  contributions  made  to  the  sub- 
ject, regarded  in  its  geological  bearings,  during  the  last 
ten  years.     Previous  to  this,  as  we  have  seen,  it  had  been 

*  Dawson:  Post-riiocene  Geology  of  Canada;  Can.  Natm-alist,  vi.,  1872. 

t  Bull.  Soc.  Geol.  de  France,  x.,  256. 

t  Annales  des  I  lines  [4],  vil.  and  xiii. 

§  Ante,  pp.  30-34:  also  Chem.  and  Geol.  Essays,  p.  100. 


aeriar 
great I 
and  c| 

soil, 

ordins 

said, 

nencyl 

showii 

ciesm 


*  Thd 

t  Pr 
ScifnceJ 
and  Hi 


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sent 

lints 
dto 
sub- 
last 


VII.] 


THE  DECAY   OF   CRYSTALLINE  ROCKS. 


251 


already  recognized  that  the  process  of  rock-decay  was  in 
operation  not  only  in  pre-glacial  but  in  pre-tertiary  times, 
and  that  the  resulting  material  was  the  source  of  the 
tertiary  clays  and  sands,  and  even,  in  certain  cases,  of 
glacial  drift  and  boulders. 

§  12.  In  a  review  of  Hartt's  volume  on  Brazil,  in  1 870, 
the  present  writer  said :  "  The  great  wasting  and  wearing 
away  of  crystalline  rocks  in  former  geological  periods,  of 
which  we  have  abundant  evidence,  is  less  difficult  to 
understand  when  we  learn  that  rocks  as  hard  as  those  of 
our  New  York  Higlilands  become  [are]  even  in  our  own 
time,  under  certain  conditions,  so  softened  as  to  offer  little 
more  resistance  to  the  eroding  action  of  a  torrent  than  an 
ordinary  gravel-bed."*  Subsequently,  in  an  account  of 
some  observations  made  in  North  Carolina,  among  the  rocks 
of  the  Blue  Ridge,  and  presented  to  the  Boston  Society 
of  Natural  Histoiy,  October  15,  1873,  he  expressed  the 
belief  tliat  the  decay  of  crystalline  rocks  was  a  process  of 
great  antiquity;  that  it  had  been  universal;  that  the  cov- 
ering of  decayed  material  now  seen  in  the  south,  at  one 
time  extended  to  the  rocks  of  northern  regions,  from  which 
it  had  been  removed  by  erosion  during  successive  agt  ,  cul- 
minating in  the  glacial  period  at  the  close  of  tiie  pliocene, 
since  which  time  the  chemical  decomposition  of  the  surface 
has  been  insignificant.  From  the  products  of  this  sub- 
aerial  decay,  it  was  then  maintained,  has  been  derived  a 
great  part  of  the  sediments  alike  of  paleozoic,  inesozoic, 
and  cenozoic  times.  The  permeable  nature  of  tlie  surface- 
soil,  formed  of  highly  inclined  strata  of  decayed  rocks,  af- 
ording  a  natural  subterranean  drainage,  explains,  it  was 
said,  both  the  absence  of  lakes,  and  the  comparative  perma- 
nency of  the  surface  to  be  remarked  in  uneroded  regions ; 
showing  that  something  more  than  ordinary  aqueous  agen- 
cies must  have  effected  the  removal  of  the  decayed  material. f 

*  The  Nation,  New  York,  Dec.  1,  1870. 

t  Proc.  Boston  Soc.  Nat.  History,  Oct.  15,  1873,  and  Amer.  Jour. 
Science,  vii.,  60;  also  Proc.  Amer.  Assoc.  Adv.  Science  for  1874,  p.  39; 
and  Hunt,  Cheni.  and  Geol.  Essays,  pp.  10,  250. 


i 


252 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


(VU. 


§  13.  This  communication  of  mine  was  speedily  fol- 
lowed by  a  paper  published  in  the  Proceedings  of  the 
Boston  Society  of  Natural  History  for  November  19, 1873, 
by  the  late  Mr.  L.  S.  Burbank,  repeating  and  insisting 
upon  the  same  conclusions,  and,  moreover,  dwelling  espe- 
cially upon  the  proceHt?  of  decay  (which  he  also  had 
studied  in  North  Carolina)  as  a  preliminary  to  the  forma- 
tion of  boulders  and  glacial  drift. 

In  accordance  with  the  views  thus  expressed  in  1870 
and  1873,  it  was  conceived  that  the  power  of  the  usual 
eroding  agents,  ice  and  water,  would  be  inadequate  to 
the  removal  of  great  areas  of  rock  unless  this  had  been 
previously  softened  by  decay,  and  in  a  review  of  the  sub- 
ject by  the  present  writer,  in  1873,  the  conclusion  was 
reached  that  the  decomposition  of  rocks  has  been  "« 
necessary  preliminary  to  glacial  and  erosive  action^  wJiick 
removed  already  softened  materials.''''  *  Such  erosion  and 
denudation  would,  in  accordance  with  this  view,  consist 
in  the  removal  of  previously  decayed  rocks,  and  the  forms 
and  outlines  of  the  sculptured  surface  thereby  exposed 
would  be  determined  by  the  varying  depths  to  which  the 
process  of  sub-ierial  decomposition  had  already  penetrated 
the  once  firm  and  solid  rock.  The  bash;  ji;:-^  depressions 
and  the  hillocks  of  the  erodtJ  surface,  rt.t  ;ess  than  the 
detached  rounded  masses  or  boulders,  were  thus,  as  the 
writer  has  ever  since  taught,  the  results  of  the  previous 
process  of  rock-decay. 

§  14.  I  had  long  before  this  time  been  led  to  insist 
upon  the  evidences  of  a  widely  spread  decomposition  of 
crystalline  rocks  in  very  early  periods  of  geological 
history.  In  an  essay,  entitled  Some  Points  in  Chemical 
Geology,  published  in  1859,t  and  another,  on  the  Chem- 
istry of  Metamorphic  Rocks,  in  1863,J  both  reprinted  in 
iiiyAiiame  of  Chemical  and  Geological  Essays,  I  have 

*  TT^rper's  Annual  Record  of  Science,  etc.,  for  1873,  p.  xlvli. 
t  <'t»'0l.  Jour.,  London,  x-.  ,  488-406. 
t  Ceo!.  Soc.  .our.,  Dublin,  x.,  85-95. 


proijd 
varioif 
the  dl 
like  A 
"uisccj 
ophylf 
tJiat  "P 

ferent 

and  ti 

study 

tion  a 


Insist 
m  of 
igical 
iuical 
tbem- 
>d  in 
\iave 


vn.] 


THE  DECAY  OF  CRYSTALLINE  EOCKS. 


253 


pointed  out  the  important  pa.'t  played  by  the  protoxyd- 
bases  liberated  by  the  sub-aerial  decay  of  feldspathic  and 
hornblendic  rocks.  Starting  from  the  conception  of  a 
primitive  terrestrial  crust  consistii^g  wholly  of  crystalline 
silicated  rocks,  we  are  forced  to  find  in  such  a  process  of 
decay  the  source  of  all  limestones  and  dolomites.  These 
are  derived  from  the  carbonates  of  lime  and  magnesia 
generated  either  directly,  during  the  process,  from  the 
bases  previously  existing  in  the  state  of  silicates,  or  indi- 
rectly, by  reactions  between  magnesian  and  alkaline  car- 
bonates formed  during  the  decay,  and  the  calcic  salts  of 
the  early  ocean.  The  chemical  genesis  of  the  lime-car- 
bonate must  evidently  precede  its  :  .-.similation  by  organ- 
isms. It  was,  in  fact,  thus  shown,  as  the  result  of  a  great 
number  of  observations,  that  fossil  sea-waters  (mineral 
waters),  representing  the  ocean  of  paleozoic  and  even  of 
meso"oic  times,  contained  large  proportions  of  calcic 
chloride,  such  as  are  required  by  this  theory.*  The  r^ui- 
tions  of  these  reactions  when  "  this  decay  of  alkaliferous 
silicates  is  sub-aerial,"  as  set  forth  in  1859  and  1863,  will 
be  found  discussed  at  length  in  the  volume  above  named, 
on  pages  23-31,  and  page  108.  [See,  for  a  certain  exten- 
sion and  modification  of  this  view  of  the  source  of  lime- 
carbonate,  ante,  pp.  178,  239.] 

§  15.  I  farther  proceeded  at  that  time  to  consider  the 
proportions  l)etween  the  alkalies  and  the  alumina  in  the 
various  characteristic  minerals  of  crystalline  rocks,  noting 
the  decrease  in  the  former  which  is  seen  when  silicates 
like  orthoclase  and  albite  are  compared  with  micas  like 
muscovite,  and  with  silicates  like  andalusite,  cj'anite,  i)yr- 
ophyllite,  and  staurolite.  The  conclusion  was  then  reached 
that  "the  chemical  and  mineralogical  constitution  of  dif- 
ferent systems  of  rocks  must  vary  with  their  antiquity," 
and  that  "it  now  remains  to  find  in  their  compartative 
study  a  guide  to  their  respective  ages  "  ;  in  which  connec- 
tion a  comparison  was  then  attempted  between  the  older 

*  Hunt,  Chein.  and  Gecl.  Essays,  pp.  41,  108,  117-121. 


i 


'in. 


SiCtf 


<isi 


254 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


[VII. 


M\ 


iim 


U'  ]'r 


I'r.  ■ 


p  •fii 


i\\ 


m 


gneisses  and  the  newer  crystalline  schists.  A  further  ap- 
plication of  tliis  principle  was  essayed  in  1878,  when  tlie 
progressive  elimination  of  the  alkalies  from  the  alumini- 
ferous  rocks  of  tlie  eozoic  groups  was  shown  by  comparing 
the  mineralogical  composition  of  the  Laurentian  with  the 
Huronian,  Montalban,  and  Taconian  crystalline  schists.* 

It  sliould  liere  be  noticed  that  the  decayed  feldspars, 
even  when  these  are  reduced  to  the  condition  of  clayti, 
have  not,  in  moist  cases,  lost  the  whole  of  their  alkalies. 
This  is  well  illustrated  in  a  series  of  analyses,  by  Mr.  E.  T. 
Sweet,  of  the  kaolinized  granitic  gneisses  of  Wisconsin,  to 
be  noticed  fartlier  on  (§  38).  From  these  analyses  it 
pppears  tluit  the  levigated  clays  from  these  decayed  rocks 
still  hold,  in  repeated  examples,  from  two  to  three  liun- 
dredths  or  more  of  alkalies,  the  potash  predominating.! 

§  16.  The  existence,  in  the  Laurentian  series,  of  lime- 
stones, not  le.d  than  that  of  sulphuretted  iron-ores  and  of 
graphite,  pointing'  to  the  existence  of  land  and  of  vegeta- 
tion during  the  dcpoRi'"ion  of  the  Laurentian,  leads  us  to 
conclude  to  a  process  of  sub-aerial  decay  of  the  more 
ancient  gneisses  in  that  far-off  period.  Such  a  process 
must  have  been  continued  in  later  times  to  give  the  mate- 
rials for  the  aluminiferous  sediments  of  the  newer  eozoic 
groups,  and  we  might  therefoi-e  hope  to  find  in  the  latter 
boulders  or  pebbles  of  more  ancient  gneisses,  such  as  are 
met  with  among  tiie  products  of  sub-aerial  decay  in  later 
deposits.  Remarkable  examples  of  such  rounded  masses, 
alike  of  Mon^al)■\^,  Huronian,  and  Laurentian  or  pre- 
Laurentian  i ypes,  ai>;  found  abundantly  in  the  very  ancient 
pre-Cam.irian  (Keweenian)  conglomerates  on  Lake  Supe- 
rior, as  1  liav3  olsewhere  described.^  Not  less  striking 
examples  of  roi,ii  ^d  ui'.sses  of  older  gneisses  occur  in  the 
Huronian  se  ies  ;.;  many  localities,  particularly  on  Lake 

*  S(,.;jnd  Geologic,    Snrvey  of  Penn.;  Azoic  Rocks,  Rep.  E.,  p.  210. 

t  iS'p,  for  these,  Irvuig  on  the  Mineral  Resources  of  AVisconsin,  Proc. 
Ame  •,  Inst.  Mining  Engineers,  vol.  viii.,  p.  305.  For  otlier  analyses,  see 
Geo.  H.  Cook,  Geol.  Survey  of  N^tv  Jersey,  Report  on  Ckys,  1878. 

}  Hunt,  Azoic  Rocks,  pp.  78, 230. 


)• 


t 
t 
FranJ 
§ 


us  to 
more 
ocess 
mate- 
eozoio 
latter 
as  are 
1  latav 
tnasses, 
r  pre- 
|anci?nt 

S^ipe- 

V  m  the 
n  Lal^e 

,  p.  210. 
Iisin,  rroc. 
lalyses,  see 
|1878. 


VII.] 


THE  DECAY  OP  CRYSTALLINE  EOCKS. 


255 


Temiscaming,  where  are  great  beds  oi  conglomerate  made 
up  chiefly  of  gneiss  boulders.*  i  ha\e  elsewhere  noticed 
a  specimen  in  my  possession  which  shows  a  perfectly  well 
defined  and  rounded  pebble  of  finely  granular  white  lime- 
stone, measuring  an  inch  in  its  greatest  diameter,  enclosed 
in  a  laminated  hornblendic  gneiss,  from  Grafton  County, 
New  Hampshire.  Slices  cut  from  the  specimen  for  the 
microscope  show  a  strong  adhesion  between  the  limestone 
and  the  quartz  and  feldspar  of  the  matrix,  without,  how- 
ever, any  evidence  of  chemical  change  at  the  contact.f 

§  17.  The  rounded  masses  and  pebbles  of  gneiss  found 
abundantly  in  several  localities  imbedded  in  the  pre-Cam- 
brian  micaceous  schists  of  the  Saxon  Erzgebirge  are  not 
less  remarkable  examples  of  the  same  kind.  I  had  in  1881 
the  opportunity  of  examining  with  Dr.  Credner  at  Leipsic 
a  large  collection  of  these,  which  consist  chiefly  of  type ; 
of  various  kinds  of  gneiss  resembling  those  of  the  Lau- 
rentian  series  as  seen  in  North  America  and  in  the  Alps. 
These  Saxon  mica-schists,  with  their  associated  gneisses 
passing  into  granulites  or  leptynites,  have  all  the  charac- 
teristics of  the  Montalban  or  newer  gneissic  series  of 
North  America  and  of  the  Alps,  to  which  I  have  elsewhere 
compared  tliem  in  two  communications,^  wherein  are 
noticed  the  above-mentioned  conglomerates,  which  had 
been  previously  studied  in  much  detail  by  Sauer,§  in  1879. 
No  one  who  sees  these  accumulations  of  rounded  masses 
of  gneiss  and  other  crystalline  rocks  entering  into  con- 
glomerates at  the  various  horizons  above  named,  can  fail 
to  be  struck  with  their  close  resemblance  to  those  which 
are  to  be  found  either  in  the  glacial  or  other  modern 
deposits,  or  lying  in  situ  as  undecayed  rounded  masses  in 
the  midst  of  decomposed  rocks.  It  is  difficult  to  resist  the 
conclusion  that  these  rounded  masses  of  the  eozoic  ages 

*  Geology  of  Canada,  1863,  p.  50. 
t  Bull.  Soc.  Geol.  de  France,  [3],  x.,  27. 

t  Geol.   Magazine,  January,  1882,  p.  39,  and  Bull.    Soc.  G6ol.   de 
France,  x.,  26. 

§  Zeitschrift  f.  d.  ges.  Naturwlss,  Band  lii. 


\' 


nT'T   I— ■!! 


256 


THE  DECAY  OP  CRYSTALLINE  ROCKS. 


tyiL 


I  ' 


N' 


j  •    i 


must  have  been  formed  under  conditions  not  unlike  those 
which  gave  rise  to  their  more  modern  representatives. 

§  18.  The  various  considerations  above  presented  thus 
lerl  the  writer,  in  1873,  to  assign  to  the  beginning  of  the 
process  of  rock-decay  an  antiquity  compared  with  which 
the  tv^^e  that  has  elapsed  since  the  drift-period  is  to  be 
regarded  as  of  short  duration.  It  was,  however,  then 
suggested  by  him  that  a  climate  and  atmospheric  condi- 
tions unlike  those  of  modern  times  might  have  favored 
the  process  in  the  earlier  ages.  Further  evidence  was 
soon  forthcoming  both  of  the  former  spread  of  this  decay 
over  northern  regions,  and  of  its  great  antiquity. 

In  1874  I  was  called  to  examine  the  condition  of  the 
great  tunnel  then  recently  opened  through  the  Hoosac 
Mountain  in  western  Massachusetts,  my  report  on  which 
was  published  by  the  General  Court  of  the  State ;  *  while 
a  note  on  the  observations  therein  made  which  have  a 
bearing  on  the  present  inquiry,  was  presented  to  the 
American  Institute  of  Mining  Engineers  in  October, 
1874.t 

§  19.  As  ti.ore  explained,  the  gneissic  rock  of  Hoosac 
Mountain,  at  the  west  end  of  the  tunnel,  700  feet  above 
the  sea,  is  completely  decayed,  the  feldspar  being  con- 
verted into  kaolin  for  a  distance  of  se\  -,-al  hundred  feet 
eastward,  along  the  line  of  the  tunnel.  The  gneiss  on  the 
crest  of  the  mountain,  2000  feet  above  the  sea,  and  on 
the  eastern  slope,  on  the  contrary,  wherever  •  xposed,  pre- 
sents the  rounded  surfaces  common  throughout  the  region, 
often  marked  by  glacial  striae,  and  without  any  appearance 
of  decay.  The  softening  and  decomposition  of  the  highly 
inclined  strata  of  gneiss  in  the  tunnel  were  described  as 
complete  for  a  distance  of  600  feet  from  the  west  portal, 
where  the  floor  of  the  tunnel  is  200  feet  from  the 
surface,  and  were  partial  at  1000  feet,  where  it  is  230  feet 
below ;  while  farther  in,  at  1200  feet,  an  included  bed  of 

♦  House  Document  No.  9,  1875, 

t  Trans.  Amer.  Inst.  Mining  Engineers,  iii.,  187. 


m:r't. 


vn.] 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


257 


I'monite,  doubtless  of  epigenic  origin,  showed  that  the 
solvent  and  oxydizing  action  of  atmospheric  waters  had 
penetrated  to  a  depth  of  more  than  300  feet  from  the 
present  surface.  At  the  western  entrance  to  the  tunnel 
the  gneiss  is  immediately  succeeded  by  the  crystalline 
limestone  and  quartzite  of  the  Taconian  (Lower  Taconic) 
series,  the  decayed  rocks  apparently  coming  from  beneath 
the  limestone.  It  was  evident  that  this  great  mass  of 
decayed  gneiss  at  the  western  base  of  Hoosac  Mountain 
is  but  a  portion  of  a  once  widely  spread  mantle  of  similar 
materials,  which  has  escaped  the  action  that  denuded  and 
striated  the  surface  of  the  other  parts  of  the  mountain. 

§  20.  Numerous  examples  of  similar  remaining  por- 
tions of  decayed  feldspathic  rock  have  been  observed  far- 
ther southward,  as  in  northwestern  Connecticut  (described 
in  §  7),  and  among  the  Laurentian  rocks  of  the  South 
Mountain,  in  Pennsylvania,  north  of  the  SchuyEvdl.  One 
of  these  decayed  portions,  at  Siesholtzville,  was  seen  in 
1875,  where  a  bed  of  magnetite,  at  that  time  mined,  was 
found  to  overlie  at  a  high  angle  a  mass  of  granitoid 
gneiss  completely  kaolinized,  but  apparently  protected 
from  erosion  by  the  incumbent  iron-ore. 

In  another  example  in  the  same  region,  about  two  miles 
south  of  Allentown,  the  Primal  or  Taconian  sandstone 
was  found  resting  for  a  little  distance  on  the  Laurentian 
gneiss,  here  much  decayed.  Wl  ere  this  had  been  exposed 
in  a  recent  cutting  (in  1875)  the  reddish  feldspathic  rock, 
still  retaining  its  color  and  its  gneissic  structure,  though 
kaolinized,  contained  numerous  "boulders  of  decomposi- 
tion," from  three  to  twelve  inches  in  diameter,  consisting 
of  undecayed  gneiss,  the  laminated  structure  of  which 
was  clearly  continuous  with  that  seen  in  the  enclosing 
decayed  mass.  These  boulders,  still  in  situ,  spheroidal  in 
form,  and  often  with  pitted  surfaces,  are  identical  with 
those  found  in  the  drift  near  by,  on  the  southeast  slope  of 
the  hill,  and  are  very  different  in  outline  from  the  half- 
angular  forms  of  adjacent  sandstone  blocks.     This  gneiss 


! 

1 

i 

H 

1 

m 

''1 

H 

i 

HI 

"MfeM 


258 


THE  DECAY  OP  CRYSTALLINE  ROCKS. 


[VII. 


Pri.j  li'ii 


;•!       •',.* 


^^^^'"■#!iHiiii 


iii' 


rock,  lying  decayed  in  place,  woidd,  unless  examined  in 
fresh  cuttings,  wliicli  show  its  liighly  inclined  foliation, 
be  readily  mistaken  for  the  drift  of  the  vicinity,  which 
has  evidently  been  derived  from  it. 

§  21.  In  my  earlier  notices  of  the  decayed  Montalban 
rocks  of  the  Blue  Ridge  in  North  Carolina,  I  had  de- 
scribed a  mantle  of  from  fifty  to  one  hundred  feet  or  more 
of  decayed  material,  but  this,  according  to  the  late  William 
B.  Rogers,  sometimes  exceeds  two  hundred  feet,  a  thick- 
ness approaching  to  that  observed  at  the  western  base  of 
Ploosac  Mountain.  I  have  since  noticed  the  decay  of  the 
Montalban  rocks  near  Atlanta,  in  Georgia,  where,  with 
local  exceptions  of  undecayed  areas  (as  in  Stone  Moun- 
tain), the  decomposition  is  more  or  less  complete,  in  many 
places,  to  a  depth  of  fifty  feet.  Here,  as  elsewhere,  the 
more  massive  rocks  include  nuclear  masses  of  undecayed 
material.  The  decayed  highly  hornblendic  gneiss  of  At- 
lanta, though  still  retaining  considerable  coherence,  has 
lost  about  two  thirds  of  its  weight,  the  specific  gravity  of 
unchanged  portions  being  2.^7-3.08,  while  that  of  the 
decayed  material  is  reduced  to  1.20,  and  even,  for  some 
specimens,  to  less  than  1.0.*  The  decomposed  gneiss  in 
this  region  is,  in  some  cases,  sufficiently  coherent  to  fur- 
nish blocks  for  certain  purposes  of  construction,  such  as 
the  walls  of  rude  chimneys,  but  at  the  surface  it  readily 
disintegrates,  yielding  a  strong  red  soil,  often  used  as  a 
brick-clay.  The  decayed  mica-schists  of  the  Montalban 
series,  which  still  retain  their  micaceous  asi)ect,  have 
been  called  hydro-mica  schists,  though  distinct  from 
those  of  the  Taconian,  with  which  they  have  been  con- 
founded. 

§  22.  The  relations  to  the  general  process  of  decay,  of 
the  large  deposits  of  cupriferous  iron-pyrites  found  in  the 
rocks  of  the  Blue  Ridge,  were  discussed  by  the  writer  in 
1873,*  after  a  study  of  the  copper-mines  opened  in  Carroll 
County,  Virginia,  in  Ashe  County,  North  Carolina,  and  in 

*  Azoic  Rocks,  p.  250. 


•1' 


VII.] 


THE  DECAY   OF  CRYSTALLINE  HOCKS. 


259 


W^ 


Polk  County,  Tennessee.*  These  ore-deposits  were  de- 
scribed as  in  each  case  in  rocks  of  the  Montalban  group  — 
the  newer  gneisses  and  mica-schists  —  and  as  constituting 
veins  or  lenticular  masses  of  posterior  origin,  consisting  es- 
sentially of  pyrite,  pyrrhotite,  and  dialer  ^.y  rite.  The  agent 
which  kaolinized  tiie  enclosing  rocks  also  oxydized  the  sul- 
phurets,  removing  the  sulphur  and  the  copper,  and  convert- 
ing the  residue  into  limonite,  which,  in  a  vertical  lode  in 
Ashe  County,  was  found  to  extend  to  depths  of  from  forty 
to  seventy  feet.  Beneath  the  oxydized  portion  is  found  in 
all  cases  the  unchanged  pyritous  mass,  seldom  carrying 
more  than  four  or  five  hundredths  of  copper.  The  limo- 
nites  thus  generated  were  for  some  years  smelted  for  iron, 
both  in  Virginia  and  in  Tennessee,  before  they  were  discov- 
ered to  be  th''  oxydized  outcrops  of  cupriferous  pyrites- 
lodes.  Between  the  unchanged  pyrites  and  the  limonite 
there  is  often  found,  in  favorable  conditions,  an  accumula- 
tion known  as  black  ore,  consisting  of  imperfectly  crystal- 
line sulphurets,  rich  in  copper,  and  sometimes  approaching 
to  bornite  in  composition,  occasionally  with  red  oxyd  and 
native  copper ;  the  whole,  doubtless,  reduced  from  the 
oxydized  and  dissolved  copper  brought  from  above. 

§  23.  The  crystalline  eozoic  rocks  of  various  ages,  in 
the  more  northern  parts  of  the  continent,  contain,  as  is 
"Well  known,  many  deposits  of  cupriferous  pyritous  ores, 
both  in  veins  and  beds  which,  like  the  enclosing  strata, 
are  undecayed,  showing  that  the  process  of  oxydation,  like 
that  of  kaolinization,  has  been  a  very  gradual  one,  going 
back  to  remote  ages.  We  have  seen,  from  the  observations 
in  the  southern  United  States,  that  the  oxydation  of  the 
sulphids,  their  conversion  into  limonite,  and  the  removal 
tlierefrora  of  the  copper  by  solution,  went  on  pari  jmssu 
with  the  decay  of  the  including  rocks,  and  hence  preceded 
their  erosion.  The  copper  thus  dissolved  was,  as  I  have 
suggested,  again  deposited  in  rocks  at  the  time  in  process 

*  Proc.  Amer.  Inst.  Mining  Engineers,  ii.,  123,  and  Amer.  Jour. 
Science,  vi.,  305;  see  also  Chem.  and  Geol.  Essays,  pp.  217,  250. 


3 


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THE  DECAY   OF  CRYSTALLINE  ROCKS. 


[VII. 


^M  !'i 


'  m 


of  formation.  The  chief  part  of  the  iron  being  left  behind, 
a  veritable  concentration  of  the  copper  would  thereby  be 
effected,  and  we  should  expect  to  find  it  separated  on 
reduction  as  a  rich  sulphide,  or  as  native  copper.  In  ac- 
cordance with  this  view,  it  was  said,  in  an  essay  on  The 
Geognostical  Relations  of  the  Metals,  in  February,  1873,* 
that  certain  deposits  of  such  copper-sulphids,  found  chiefly 
in  limestones,  probably  of  Cambrian  age,  which,  in  the 
province  of  Quebec,  as  at  Acton  and  Durham,  lie  along 
the  northwest  border  of  the-  crystalline  Huronian  belt, 
might  be  formed  from  "the  results  of  oxydation  of  the 
cupriferous  beds  which  abound  in  the  crystalline  schists 
of  these  mountains,  from  which  the  dissolved  metal  accu- 
mulated in  basins  at  their  foot,"  as  suggested  by  Murchison 
with  regard  to  the  cupriferous  Permian  strata  near  the 
crystalline  schists  of  the  Ural  Mountains.  "To  a  like 
process,"  it  was  said,  "  we  may  perhaps  ascribe  the  rich 
deposits  of  native  copper  in  the  Keweenaw  amygdaloids 
and  conglomerates,  which  rest  upon  the  ancient  Huronian 
schists." 

§  24.  The  farther  extension  of  this  view  to  the  meso- 
zoic  sandstones  of  Connecticut,  New  Jersey,  and  Pennsyl- 
vania, well  known  to  be  very  often  impregnated  with 
copper  disseminated  in  the  form  of  sulphids,  sometimes 
associated  with  organic  remains,  is  obvious.  It  is  to  be 
noticed  that  the  strata  in  question  are  generally  deposited 
directly  upon  eozoic  rocks,  from  the  ruins  of  which  they 
were  formed,  and  that  these,  in  our  hypothesis,  furnished 
the  dissolved  copper  from  which  the  disseminated  ores 
were  derived.  If  this  view  be  admitted,  we  have  farther 
and  independent  evidence  that  the  decay  of  the  eozoic 
rocks,  with  that  of  their  contained  cupriferous  sulphurets, 
was  going  on  in  that  pre-Cambrian  period  in  which  the 
Keweenian  series  was  accumulated,  and  was  still  active  in 
mesozoic  time. 

§  25.  Not  less  striking  examples  of  rock-decay  are  seen 

•  Proc.  Amer.  Inat.  Mining  Engineers,  i.,  341. 


LVII. 

ind, 
y  be 
[on 
i  ac- 
The 
^73,* 
liefly 
a  the 
along 

belt, 
3£  the 
ichists 
1  accu- 
•cbison 
;ar  the 

a  VikQ 
he  ricb 
;daloids 
uronian 

e  meso- 
>ennsyl- 
ed  with 
metimea 

lis  to  be 
eposited 

lich  they 
lurnished 
,ted  orea 
e  farther 
,e  eozoio 
ilphurets, 
rhich  the 
active  in 

are  seen 


vn.] 


THE  DECAY  OP  CRYSTALLINE  ROCKS. 


261 


in  the  great  Appalachian  valley,  of  which  the  Hoosac 
Mountain,  the  South  Mountain,  and  the  Blue  Ridge  form 
parts  of  the  eastern  rim.  Therein,  as  is  well  known,  large 
quantities  of  limonite  are  mined,  from  New  England  to 
Alabama.  This  ore,  as  well  as  its  accompanying  man- 
ganese-oxyd,  is  clearly  of  epigenic  origin,  and  is,  in  most 
cases,  still  imbedded  in  ancient  and  highly  inclined  clayey 
strata  derived  from  the  sub-aerial  decay  in  situ  of  the 
schists  which  accompany  the  dolomites  and  quartzites  of 
the  Primal  and  Auroral  (Taconian)  series.  These  oxy- 
dized  ores  have  been  formed  hy  the  transformation  of 
included  masses  of  pyrites  and  of  carbonates  of  iron  and 
manganese.*  The  evidences  of  the  pyritic  origin  of  many 
of  these  limonites  is  similar  to  that  for  those  of  the  Blue 
Ridge  (§  22),  namely,  their  association  with  unchanged  pyr- 
ites. An  example  of  this  is  seen  in  the  so-called  Copperas 
mine  at  Breinigsville,  near  Trexlertown,  Pennsylvania, 
long  ago  described  by  H.  D.  Rogers,!  where  large  quanti- 
ties of  pyrites  have  been  mined  from  the  same  openings 
which  yield  limonite.  Some  of  this  I  found  still  retain- 
ing the  imitative  forms  of  the  adjacent  pyrites  (from 
which  Rogers  had  inferred  a  conversion  of  limonite  into 
pyrites),  while  the  waters  of  the  mine,  like  those  of  others 
in  the  region,  were  charged  with  sulphuric  acid  and  with 
iron-sulphate.  Another  remarkable  locality,  where  pyr- 
ites replaces  the  limonite  in  depth,  was  visible  in  1875  at 
Seitzinger's  mine,  near  Reading,  Pennsylvania,  and  other 
similar  cases  are  reported  in  the  vicinity ;  while  at  Salona, 
in  the  Nittany  valley,  the  association  of  pyrites  with  lim- 
onite at  this  same  geological  horizon  has  also  been  noticed. 
§  26.  The  association  of  siderite  or  iron-carbonate  with 
the  limonites  of  the  Appalachian  valley  is  well  known 
east  of  the  Hudson,  in  New  York  and  Massachusetts. 
This  mineral  is  often  manganesian,  and  passes  into  nearly 
pure  rhodocrosite.   Examples  of  the  association  of  siderite 

•  Azoic  Rocks,  pp.  201-203. 

t  Geology  of  Pennsylvania,  i.,  265. 


i 


I 


..  ii.i 


NI1il!ll{{|ti{llfi 


262 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


[VII. 


with  liuionite  are  also  seen,  among  other  localities,  near 
Hackettstown,  New  Jersey,  and  near  Hanover,  York 
County,  Pennsylvania.  These  carbonates,  or  at  least  the 
limonite  and  manganese-oxyj  derived  from  them,  are 
found  in  close  association  with  pyritous  deposits,  as  we 
have  seen  near  Trexlertown.  In  like  manner,  pyrites  and 
siderite,  as  is  well  known,  often  occur  side  by  side  in  the 
coal-measures. 

§  27.  I  have  elsewhere  considered  the  change  in  sider- 
ite under  the  action  of  oxydizing  atmospheric  waters, 
which  proceeds  like  that  in  feldspathic  rocks,  from  with- 
out inwards,  and  is  necessarily  accompanied  with  consid- 
erable diminution  of  volume,  which,  in  the  conversion  of 
a  siderite  of  specific  gravity  3.6  into  a  limonite  of  the 
same  density,  would  equal  19.5  per  cent. 

"  The  evidences  of  this  contraction  may  be  seen  in  the 
structure  of  the  limonite  derived  from  siderite,  which  often 
forms  a  porous  or  spongy  mass.  In  the  case,  however,  of 
nodules  or  blocks  of  solid  ore,  the  conversion  beginning  at 
the  outside  of  the  mass,  an  external"  layer  of  compact 
limonite  is  formed,  and  then  another  within  this,  and  still 
another,  till  the  change  is  complete.  The  void  space 
resulting  from  contraction  is  then  found  between  the 
■layers,  which  are  arranged  like  the  coats  of  an  onion,  or 
sometimes  wholly  at  the  centre,  where  a  cavity  will  be 
formed,  holding  in  many  cases  more  or  less  clay  or  sand, 
the  impurities  of  the  carbonate,  which  have  been  sepai-ated 
in  the  process  of  conversion  into  limonite.  In  this  way 
are  formed  the  hollow  masses  sometimes  known  as  bomb- 
shell ore,  which  occasionally  include  nuclei  of  unchanged 
sideiite.  Their  structure  will  generally  serve  to  dis- 
tinguish the  sideritic  from  the  pyritic  limonites."  * 

In  the  paper  just  quoted  I  have  also  considered  the 
change  of  volume  which  should  accompany  the  conver- 
sion  of  pyrites  into  limonite,  a  process  generally  com- 

*  The  Genesis  of  Certain  Iron  Ores;  read  before  the  Amer.  Assoc. 
Adv.  Science,  1880:  Canadian  Naturalist  for  December,  1880,  ix.,  434. 


IVIL 

J,  near 
York 
ist  the 
m,  are 
,  as  we 
tes  and 
3  in  the 

n  sider- 
waters, 
,m  with- 
1  consid- 
ersion  of 
e  of  the 

en  in  the 

lich  often 

iwever,  of 

rinning  at 

;  compact 

,,  and  still 
oid  space 
;ween  the 
onion,  or 
ty  will  be 
^y  or  sand, 
separated 
.  this  way 
i\  as  bomb- 
unchanged 
Ive   to  dis- 

iidered  the 
•he  conver- 
■rally  cora- 

J  Atner.  Assoc, 
bo,  Ix..  434. 


VU.] 


THE  DECAY   OF  CRYSTALLINE  ROCKS. 


263 


plicated  by  the  loss  of  a  part  of  the  iron  as  a  soluble 
sulphr.te. 

§  28.  Portions  of  the  contorted  and  often  highly  in- 
clined schistose  strata  enclosing  the  limonite  ores  in  the 
Appalachian  valley,  are  still  found  but  partially  decayed, 
and  while  some  are  converted,  to  depths  of  100  feet  or 
more,  into  white  or  variously  colored  clays,  others  retain 
more  or  less  of  their  original  texture.  From  the  presence 
in  some  of  these  of  considerable  quantities  of  a  hydrous 
micaceous  mineral,  having  the  composition  of  damourite, 
they  have  been  called  damourite-slates.  There  are  many 
reasons  for  believing  that  these  ancient  rocks  were  thus 
folded,  and  were  decomposed,  before  the  deposition  of  the 
Trenton  and  Chazy  limestones,  which  rest  upon  them  in 
the  outlying  or  western  valleys  of  the  Appalachian  region, 
alike  in  Pennsylvania  and  in  Alabama.* 

§  29.  Professor  Lesley,  in  discussing  the  history  of  the 
limonites  of  the  Appalachian  valley,  has  fallen  into  an  error 
with  regard  to  my  view  of  their  origin.  Referring,  in 
1876,  to  the  opinions  expressed  in  my  paper  of  1873 
(already  noticed  in  §  13)  touching  the  decayed  crystalline 
rocks  of  the  Blue  Ridge,  that  "  the  iron-oxyd  from  these 
has  been  in  great  part  dissolved  out  by  subsequent  pro- 
cesses, and  was  the  source  of  the  immense  deposits  of 
hydrous  iron-ores  "  in  question,  he  supposes  me  to  "  con- 
jecture that  the  ores  lying  along  the  eastern  edge  of  the 
Shenandoah  valley  had  been  washed  into  it  from  or  across 
the  Blue  Ridge."    This  Lesley  properly  qualifies  as  an 

*  The  fact  of  the  existence  at  various  points  in  the  Appalachian  valley 
of  beds  of  limonite  interstratified  in  tertiary  clays  with  lignite,  as  at 
Brandon,  Vermont,  must  not  be  overlooked.  First  recognized  by  Edward 
Hitchcock,  and  subsequently  noticed  by  liCsley,  in  1864,  the  later  observa- 
tions of  Prime,  Lewis,  and  others,  show  the  presence  of  these  ores  and 
clays,  with  lignites,  at  various  points  in  Pennsylvania  and  in  Alabama,  as 
well  as  in  Vermont.  These  are  but  fragments  of  what  were  probably 
once  extended  deposits,  and  although  of  geological  interest  as  resulting 
from  re-solution  and  re-arrangement,  in  tertiary  time,  of  a  portion  of  the 
ancient  decayed  strata  of  the  valley,  are  of  comparatively  little  economic 
Importance.    (H.  C.  Lewis,  Proc.  Acad.  Nat.  Sci.  Phila.,  Oct.  27,  1879.) 


i 


1 

I 
J 


264 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


[VII. 


'  'f    ;  kvaki  III 


"absurd  conclusion,"  since  it  does  not  explain  the  origin 
of  the  limonites  found  in  the  back  or  central  valleys,  a 
hundred  miles  or  more  to  the  west  of  the  Blue  Ilidge ; 
and  declares  that  had  R.  S.  M.  Jackson  continued  his 
geological  studies,  "he  would  have  published  a  satisfac- 
tory refutation  of  this  surface-drainage  theory  of  the  brown 
hematites."  * 

§  30.  Those  who  have  read  what  I  had  written  on  the" 
subject  previous  to  1876,  and  especially  my  discussion  of 
the  origin  of  these  ores  in  1874,f  are  aware  that  I  have 
never  advocated  any  such  theory.  I  have,  it  is  true, 
endeavored  to  find  in  the  insoluble  products  of  decay  of 
these  ancient  crystalline  rocks,  the  source  not  only  of  the 
clays  and  sands  of  the  succeeding  sediments,  but  of  their 
contained  iron,  whether  diffused,  or  accumulated  in  ore- 
masses.  I  have,  however,  at  the  same  time,  always  main- 
tained that  the  ores  associated  with  the  so-called  Primal 
and  Auroral  rocks  of  the  Appalachian  basin,  like  those  of 
the  higher  horizons,  up  to  the  coal-measures  inclusive, 
were  deposits  contemporaneous  with  the  strata  in  which 
the  valleys  were  subsequently  excavated;  and  that,  save 
in  some  cases  where,  as  mentioned  below,  it  was  appar- 
ently deposited  as  peroxyd,  the  iron  was  accumulated  in 
the  form  of  carbonate,  and  more  rarely  of  sulphid ;  from 
the  alteration  of  both  of  which,  in  sitUy  the  limonites  have 
been  formed.  This  view,  which,  as  I  then  showed,  was 
that  advocated  by  Charles  Uph^m  Shepard,  in  1837,  for 
the  limonites  of  western  New  England,  was  the  same  as 
that  put  forward,  in  1838,  by  R.  S.  M.  Jackson  himself,  who 
maintained,  as  stated  in  the  language  of  Professor  Lesley, 
"that  the  ore  belonged  to  the  stratified  limestone  beds 
themselves,  and  had  been  set  free  from  them  by  chemical 
and  mechanical  decomposition."  This  history  was  clear 
to  Dr.  Persifor  Frazer,  who,  having  remarked  that  "  the 
theory  of  alteration  in  situ  of  various  iron-minerals  result- 

*  Second  Geol.  Survey  of  Penn.,  Report  A,  p.  83. 

t  Trans.  Amer.  Institute  Mining  Engineers,  iii.,  pp.  418-421. 


rocJ 

ore-j 

gin\ 

fissi 

witi 

beds 
tiin( 
the 


f 


1 1 


LI. 

in 

,a 

je; 

his 

Ug- 

)wn 

the 

n  of 

have 

true, 

ay  of 

i  the 

their 

a  ore- 

main- 

Primal 

iiose  oi  ; 

}lus\ve, 
which 
t,  save 
aijpar- 

ated  in 
from 
es  have 
ed,  ^vas 
837,  for 
same  as 

,elf,  wlio 
Lesley,  ' 
^e  beds 
liemical 
as  clear 
at  "the 
[Is  result- 

18-421. 


vm 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


265 


ing  in  the  formation  of  many  of  these  limonites,  advanced 
by  C.  U.  Shepard,  and  ably  discussed  and  adopted  by 
Dr.  T.  Sterry  Hunt,  cannot  be  disregarded  in  seeking  the 
cause  which  produced  these  limonites,"  adds,  "In  1838, 
and  independently  of  Prof.  Shepard's  observations,  Dr. 
R.  S.  M.  Jackson  reported  to  Prof.  H.  D.  Rogers  sub- 
stantially the  same  conclusion,  from  the  study  of  the  limo- 
nites of  Centre  and  Huntingdon  Counties."  ■ 

§  31.  This  same  view  was  in  fact  well  stated  by  Lesley 
himself  in  1864,  when  he  said,  "  The  brown-hematite  ore- 
deposits  of  Mount  Alto  follow  the  edge  of  the  slates  and 
sandy  limestones,"  and  are  "but  the  residues  of  these 
beds  after  decomposition  and  dissolution,  the  honey- 
combed and  altered  edges"  of  the  slates  and  limestones 
themselves,  "after  the  lime  has  been  washed  out  of  them, 
and  their  carbonated  and  sulphuretted  ii'on  has  been 
hydrated  and  peroxydized ;  the  slates  having  formed  the 
red  and  white  clays."  He  farther  described  at  one  locality 
of  the  region  in  question  "  an  outcrop  of  almost  unchanged 
blue  carbonate  of  iron  and  iime,  several  feet  thick.  .  .  . 
and  evidently  in  part  changing  into  honeycombed  brown 
hematite  ore."  f 

§  82.  In  1867,  Mr.  Benjamin  Smith  Lyman  expressed 
similar  views  in  his  account  of  the  limonites  of  Smyth 
County,  Virginia,  found  lying  below  the  limestones  of 
No.  11.  (Taconian),  where  many  localities  "  show  the  ore 
unmistakably  in  regular  beds  conformable  to  the  other 
rocks."  He  at  the  same  time  supposed  that  some  of  these 
ore-deposits  are,  like  one  noticed  in  Wythe  County,  Vir- 
ginia, due  to  "the  weathering  of  the  upper  part  of  a 
fissure-vein  of  iron-pyrites,''  but  maintains  that  the  ores, 
with  such  exceptions  as  this,  were  "  deposited  in  regular 
beds,  of  greater  or  less  extent  and  thickness,  at  the  same 
time  with  the  other  rocks,"  and  from  the  presence  in 
the  limonite  of  occasional  masses  of  carbonate  of  iron, 

•  Second  Geological  Survey  of  Penn.,  Report  C,  p.  143.'  ., 
t  Amer.  Philos.  Soc.  Proc,  ix.,  pp.  471-475. 


'i 


266 


THE  ^ZCAY  OP  CRYSTALLINE  ROOKS. 


[VU. 


in  11 


concludes  that  it  vas  originally  deposited  in  this  con- 
dition.* 

§  33.  But  while  it  is  apparent  that  the  ores  in  question, 
now  found  imbedded  in  clays  resulting  from  the  decompo- 
sitio:.  in  situ  of  ancient  schists,  were,  previous  to  that 
decay,  enclosed  therein  as  massive  siderite  or  pyrites,  we 
must  not  overlook  the  evidences  that  in  certain  cases  a 
process  of  segregation  of  diffused  iron-oxyd  has  played  an 
important  part,  alike  in  ancient  and  in  modern  times,  in 
the  genesis  of  limonites.  Setting  aside,  as  not  relevant 
to  our  present  inquiry,  the  formation  of  bog  iron-ores  and 
ochres,  which  are  directly  deposited  from  ferrous  solutions 
by  peroxydation  and  precipitation,  we  here  recall  the  con- 
tribution to  the  theory  of  the  origin  of  imbedded  iron- 
ores  made  by  the  late  William  B.  Rogers.  The  ferrous 
carbonate  found  in  the  rocks  of  the  coal-measures  has, 
as  he  has  endeavored  to  show,  been  generated  from  dif- 
fused ferric  oxyd  by  a  process  of  reduction,  carbonation, 
and  solution,  through  waters  charged  with  organic  matters 
from  vegetable  decay ;  the  carbonate  of  iron  thus  formed 
remaining  in  some  cases  diffused  through  the  sediments, 
and  in  others  becoming  concentrated  by  accrotion.f 

§  34.  This  view  is  to  be  supplemented  by  the  consid- 
eration that  carbonated  solutions  of  ferrous  oxyd  formed 
as  above  (and  often  containing  organic  acids)  may,  by 
reacting  with  beds  of  carbonate  of  lime,  effect  a  gradual 
replacement  of  the  latter  by  carbonate  of  iron.J    The 

*  Proc.  Amer.  Assoc.  Adv.  Science,  1867,  p.  114. 

t  Geological  Survey  of  Penn.,  1858,  ii.,  757. 

X  J.  Ville  found  one  litre  of  carbonated  water  at  the  ordinary  pressure 
to  hold  in  solution  at  2(f  C.  1.142  grammes  of  ferrous  carbonate,  and  at 
116°  C,1.390  grammes.  From  these  solutions  neutral  alkaline  carbonates 
readily  throw  down  the  ferrous  carbonate,  themselves  passing  to  the  state 
of  bicarbonates;  and  carbonates  of  lime  and  magnesia  produce  the  same 
effect,  though  more  slowly.  (Comptes  Rendus  del' Acad,  des  Sciences, 
October.  1881,  vol.  xciii..  p.  443. )  The  present  writer  found  recently  pre- 
cipitated ferrous  carbonate  to  be  temporarily  much  more  soluble,  under 
the  above  conditions,  yielding  supersaturated  solution^,  which  in  close 
vessels  spontaneously  deposit,  after  many  hours,  a  large  part  of  the  car- 
bonate in  a  crystalline  condition. 


II. 


on- 


VII.] 


THE  DECAY  OP  CKYSTALLINE  ROCKS. 


2G7 


ion, 
Lipo- 
that 
J,  we 
iea  a 
3(1  an 
>e9,  in 
evant 
69  and 
Lutions 
tie  con- 
id  iron- 
ferrous 
res  l^as, 
•rem  di£- 
)onation, 
p  matters 
^s  formed 
cUnients, 

"•^        -A 
e  coiisia- 

;d  formed 

may,  ^Y 
a  gradual 

n4    ^^' 


lonate,  and  at 
Ine  carbonates 
li2  to  the  state 
[duce  the  same 
I   des  Sciences, 

la  recently  pte- 
LoluWe,  under 

Lh\cb  in  close 
Vrt  of  tbe  car- 


transformation  of  diffused  ferric  oxyd  in  sediments  into 
massive  limonite,  imbedded  therein,  is  thua  a  twofold 
process,  involving,  first,  the  intervention  of  reducing  solu- 
tions converting  the  peroxyd  into  ferrous  carbonate,  and 
the  concentration  of  the  latter ;  and  second,  the  change 
of  this  latter,  through  peroxydation  and  hydration,  into 
limonite. 

[Dr.  N.  S.  Shaler  has  shown  the  important  bearing  of 
the  reaction  just  pointed  out  (by  which  beds  of  carbonate 
of  lime  are  gradually  changed,  through  replacement,  into 
carbonate  of  iron)  upon  the  production  of  beds  of  fer- 
riferous limestone,  and  of  iron-ores,  at  various  geological 
horizons.  This  he  especially  notes  in  the  many  limestone 
layers  found  in  Kentucky  and  Ohio,  in  the  great  mass  of 
sandstones  and  shales  of  the  carboniferous  series,  where  he 
points  out  that  the  fact  that  the  iron  is  confined  to  the 
upper  part  of  the  limestone  layers  shows  their  transfor- 
mation by  the  action  of  ferrous  solutions  from  above.  He 
farther  adduces  the  iron-ore  beds  at  different  horizons 
between  the  base  of  the  Devonian  shales  and  the  great 
sandstone  (Oneida-Medina),  which  in  the  Appalachian 
basin  forms  the  basal  member  of  the  Silurian.  These 
include,  besides  iron-carbonate  superficially  changed  into 
limonite,  the  widely  spread  deposit  of  so-called  fossil  ore, 
or  Clinton  ore,  evidently  a  changed  marine  limestone,  in 
which  the  iron  is  now  in  the  form  of  scaly  red  hematite. 
The  genesis  of  this  anhydrous  peroxyd  is  not  yet  clearly 
explained,  but  it  is  to  be  remarked  that  concretions  of 
similar  hematite  are  found,  instead  of  siderite,  in  certain 
shales  in  the  coal-measures  in  Ohio.  Shaler  is  careful  to 
distinguish  between  ore-beds  from  replaced  limestone  and 
the  concretionary  carbonate  ores  which  are  found  in 
shales,  where  there  is  no  evidence  of  the  previous  accu- 
mulation of  calcareous  masses.]* 

§  35.   It  is  evident  that  the  first  stage  of  the  process 
indicated  by  Rogers  as  takmg  place  in  sediments  a^  yet 

*  Geol.  Survey  of  Kentucl^y,  1877,  iii.,  163-167. 


I 


IP 


268 


THE  DECAY  OP  CRYSTALLINE  ROCKS. 


[VII. 


unconsolidated,  may  also  be  set  up  in  the  disintegrated 
ferriferous  moterials  resulting  from  the  sub-aerial  decay  of 
rooks,  and  still  undisturbed ;  that  is  to  say,  that  the  infil- 
tration of  waters  holding  dissolved  organic  matter  may 
give  rise  in  the  decomposed  mass  to  concretions  of  ferrous 
carbonate,  which  are  subsequently  changed  into  limonite. 
In  this  way,  a  concentration  may  be  effected,  through 
which  rocks  originally  containing  a  small  portion  of  dif- 
fused iron-oxyd  come  to  include  masses  of  limonite. 
Illustrations  of  this  process  are  sometimes  seen  in  the 
decay  of  ferriferous  limestones  or  dolomites,  in  the  resid- 
uum of  which  we  find  the  iron  accumulated  in  the  shape 
of  crusts  or  layers  of  limonite. 

An  instructive  example  of  an  analogous  process  is  seen 
in  the  limonite  which  on  Staten  Island,  New  York,  is 
found  imbedded  in  a  layer  of  brownish  earthy  material, 
sometimes  attaining  a  thickness  of  twelve  feet.  This  rests 
immediately  upon  the  sevpentine-rock  of  the  region,  into 
which  it  graduates,  and  from  the  sub-aerial  decay  of  which 
it  has  evidently  been  derived ;  the  lower  portion  of  the 
earthy  matrix  still  preserving  the  peculiar  jointed  structure 
of  the  underlying  serpentine.  This  decomposed  material, 
though  including  botryoidal  crusts,  geodes,  and  concretion- 
ary grains  of  limonite,  with  occasional  druses  of  chalce- 
dony and  of  quartz  crystals,  retains  considerable  coherence. 

The  source  of  this  limonite  seems  to  have  been  the 
iron-oxyd  liberated  by  the  decay  of  the  ferriferous  ser- 
pentine, and  the  proportion  of  ore  in  the  superjacent  mass 
shows  a  direct  relation  to  the  color  and  apparent  propor- 
tion of  iron-silicate  in  the  serpentine  beneath.  This  limo- 
nite, which  is  now  mined  to  a  considerable  extent,  contains, 
as  several  analyses  have  shown,  from  one  to  two  hun- 
dredths of  chromic  oxyd,  which  is  also  known  to  be 
present  in  small  amount  in  the  serpentine.  An  impure 
argillaceous  specimen,  containing  only  59.63  of  ferric 
oxyd,  yielded  the  writer  2.81  of  chromic  oxyd  in  a  con- 
dition readily  soluble  in  chlorhydrio  acid. 


I. 


VII.] 


THE  DECAY  OF  CRYST^VLLINE  BOCKS. 


2G9 


id      - 
of 

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ay 

ite. 

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dif- 
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the 
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seen 
rk,  is 
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of  the 
ucture 

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lis  linio- 
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o  hun- 
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a  con- 


§  86.  Dr.  N.  L.  Britton,  of  the  School  of  Mines  of 
Columbia  College,  New  York,  in  whose  company  I  lately 
had  an  opportunity  of  visiting  this  interesting  locality, 
published,  in  1880,  a  geological  map,  with  sections,  and  a 
description  of  Staten  Island.*  He  tlierein  shows  that  the 
earthy  material  in  which  the  limonite  is  imbedded  is  con- 
fined to  the  tops  of  certain  hills  of  serpentine,  being 
absent  alike  from  other  similar  hills  adjacent,  and  from 
intervening  valleys  cut  into  the  serpentine,  and  he  has 
connected  this  distribution  of  the  ore-bearing  stratum 
with  the  facts  of  the  local  glaciation  of  the  region,  to 
which  he  has  devoted  much  attention.  It  is,  I  think,  evi- 
dent that  the  decay  of  the  serpentine,  and  the  concentra- 
tion, in  the  residuu  n,  of  its  iron  in  the  form  of  limonite, 
was  a  process  anterior  to  the  glacial  erosion,  and  that  the 
ore-banks  are  areas  of  the  decayed  material  which  escaped 
this  action. 

§  37.  Turning  now  to  the  valley  of  the  Mississippi,  we 
find  that  Pumpelly,  in  his  geological  survey  of  Missouri, 
showed,  in  1873,  that  the  decay  in  situ  of  granitic  rocks, 
and  of  quartziferous  porphyry,  has  left  great  rounded 
blocks  of  these  crystalline  rocks ;  while  the  conversion  of 
the  porphyry  into  clay,  and  its  subsequent  removal,  have 
liberated  included  veins  or  masses  of  crystalline  hematite, 
giving  rise  to  an  accumulation  of  detrital  iron-ore,  such 
as,  at  the  well  known  Iron  Mountain,  forms  a  covering 
over  the  surface  of  the  hill  of  porphyry.  From  the  pres- 
ence of  stratified  deposits  of  this  detrital  ore  in  the 
ancient  Cambrian  strata  around  the  base  of  the  hill, 
Pumpelly  inferred  that  the  decay  of  the  porphyry  was 
already  complete  to  a  considerable  depth,  at  this  early 
period.f  His  observations  and  deductions  were  not  known 
to  me  when,  in  the  same  year,  I  published  my  conclusions 
as  to  the  great  antiquity  and  the  universality  of  the  pro- 
cess of  rock-decay. 

•  Annals  New  York  Acad.  Sciences,  vol.  ii.,  part  6. 

t  Geology  of  Missouri;  Report  on  Iron  Ores  and  Coal  Fields,  pp.  8-12. 


270 


THE  DECAY  OP  CRYSTALLINE  ROCKS. 


(VH. 


K 


I 


§  88.   Proceeding   from   Missouri  northward,  we  find 
that  in  Minnesota,  as  shown  by  C.  A.  White,*  in  1870, 
and  by  N.  H.  Winchell,  in  1874,  the  aneien^  granitoid 
rocks,  when    protected  by  cretaceous   strata,  support  a 
kaolinized  layer  of  considerable  thickness.f     In  Wiscon- 
sin a  similar  condition  of  things  is  found  beneath  the 
Potsdam  sandstone  in  the  central  part  of  the  State,  as 
described,  by  Irving,  in  1870, J  in  an  essay  which  is  a 
valuable  contribution  to  the  literature  of  kaolin,  and  con- 
tains many  analyses  of  the  decayed  rocks  of  the  region,  by 
Mr.  E.  T.  Sweet,  which  have   been  already  referred  to 
(§  16).    Further  details  of  the  same  region  and  its  kaolins, 
with  analyses,  as  before,  were  given  by  Irving  in  n^.  essay, 
in  1880,  on  the  Mineral  Resources  of  Wisconsin. §     In 
Jackson  and  Wood  Counties,  where  the  crystalline  (Lau- 
rentian)  rocks  are  covered  by  a  thin  sheet  of  Potsdam 
sandstone,  the  river-valleys,  cutting  through  this,  expose 
the  kaolin,  which  "occupies  its  original  position,  retaining 
sometimes  the  structure  of  the  unaltered  rock."     This  ia 
derived  from  the  decay  in  situ  of  certain  bands,  which, 
passing  downward,  graduate  into  unaltered  feldspathic 
rock.     Save  where  this  mantle  of  decayed  material  has 
been  protected  by  the  paleozoic  sandstone,  the  crystalline 
rocks  are  there  seen  for  the  most  part  in  an  undecayed 
condition,  evidently,  as  Irving  remarks,  from  the  removal 
of  the  decayed  material  by  "  the  denuding  action  of  the 
drift."    In  some  portions  of  the  driftless  area  of  this  region 
the  unprotected  gneisses  still  retain  their  mantle  of  kaolin- 
ized material. 

§  39.  From  the  facts  before  us,  it  is  clear  that  the  decay 
of  the  eozoic  crystalline  rocks  was  already  far  advanced 
in  pre-Cambrian  times.  I  am  informed  that  similar  evi- 
dence is  afforded  in  Sweden  by  the  presence  of  decom- 

*  Geology  of  Iowa,  i.,  124. 

t  Second  Annual  Rep.  Geol.  Minnesota,  pp.  162,  166,  207;  also  Hunt, 
Chem.  and  Geol.  Essays,  p.  250. 

I  Trans.  Wisconsin  Academy,  etc.,  ill.,  13. 

§  Trans.  Amer.  Inst.  Mining  Engineers,  viiL,  103. 


the 


ii 


yn.] 


THE  DECAY   OP  CRYSTALLINE   llOCKH. 


271 


Ino 

has 

line 
sayed 

xoval 
the 
region 
:aoUn- 

decay 

anced 

ar  evi- 

ieuom- 

Huntf 


posed  rock  beneatli  Cumbrian  strata.  Prr  f.  A.  Geikie  has 
moreover  shown  that  the  sculpturing  of  the  gneiss  rocks 
of  western  Scothmd,  a  jjrocess  which  I  have  maintained 
to  be  dependent  on  previous  sub-aerial  decay,  was  effected 
before  the  deposition  of  the  Cambrian  sandstones,  which 
there  rest  upon  ancient  roches  moutonnees* 

§  40.  It  might  be  supposed,  from  their  stability  under 
ordinary  atmospheric  influences  in  regions  protected  by 
vegetation,  that  all  such  portions  of  decayed  eozoic  rocks 
as  still  exist  in  driftless  or  in  protected  areas  date  from 
the  (lawn  of  paleozoic  time,  did  we  not  know  that  the  same 
processes  of  decay  have  been  active  in  subsequent  ages, 
as  is  shown  by  the  decay  of  eruptive  rocks  of  later 
periods.  An  example  of  this,  which  shows  at  the  same 
time  the  little  progress  made  in  the  process  of  decay  since 
the  drift-period,  is  seen  in  Canada,  at  Montreal,  where,  to 
the  south  of  Mount  Royal,  the  nearly  horizontal  beds  of 
the  impure  Trenton  limestone  are  found,  in  sheltered 
places,  deeply  decayed,  and  porous  from  the  removal  of 
their  carbonate  of  lime,  and  are  moreover  traversed  by 
dikes  of  dolerite  and  other  feldspathic  rocks,  themselves 
decayed  to  considerable  depths ;  while  near  by,  and  espe- 
cially to  the  north  of  the  mountain,  where  glaciation  did 
its  work  of  removing  alike  decayed  aqueous  and  igneous 
rocks,  the  eroded  surftices  of  both  of  these  are  found  to  be 
hard  and  comparatively  unchanged,  beneath  a  thin  layer 
of  soil  and  vegetation,  as  described  by  J.  W.  Dawson. 

Another  instance  is  afforded  by  a  dike  intersecting  the 
Potsdam  sandstone  in  this  vicinity,  which  is  found  to  be 
converted,  to  a  depth  of  twenty  feet  or  more,  into  a  plastic, 
highly  aluminous  clay,  which,  from  the  presence  of  por- 
tions of  titanium  and  chromium,  is,  we  may  conjecture, 
derived  from  a  doleritic  rock.f 

§  41.  Rigaud  Mountain,  an  igneous  mass  rising  through 
the  Potsdam  sandstone,  and  occupying  several  square 

•  Nature,  August  26,  1880,  p.  403.  '  , 

t  Report  Geol.  Survey  of  Canada,  1878-79,  H.,  p.  7. 


,1 


272 


THE  DECAY  OP  CRYSTALLINE  ROCKS. 


[vn. 


miles  on  the  south  side  of  the  Ottawa,  near  its  confluence 
with  the  St.  Lawrence,  is  probably  of  paleozoic  age,  and 
consists  in  large  part  of  a  reddish  granitoid  orthoclase 
rock.  Considerable  areas  of  its  surface,  lying  lower  than 
the  surrounding  crests  of  the  mountain,  are  covered  to  a 
depth  of  seven  feet  or  more,  in  places,  v/ith  well  rounded 
boulders  from  three  to  eighteen  inches  in  diameter,  con- 
sisting wholly  of  the  rock  of  the  mountain,  with  the 
exception  of  a  few  masses  of  sandstone.  The  areas  so 
covered  attain,  in  their  higher  parts,  an  elevation  of  about 
280  feet  above  the  Ottawa,  but  slope  gently  both  to  the 
south  and  the  north.  The  boulders  are  very  rare  on  the 
north  slope  of  the  mountain  and  at  its  northern  base,  but 
are  abundant  on  the  southern  slope  and  in  the  low-lying 
clay-covered  plains  to  the  southward.*  These  well 
rounded  masses,  spread  over  so  much  of  the  mountain, 
are  apparently  boulders  of  decomposition,  still  in  situ^ 
having  escaped  the  denuding  agents  of  the  drift-period. 

§  42.  Examples  of  more  recent  sub-aerial  decay  of 
crystalline  rocks,  under  peculiarly  favorable  conditions, 
were  in  1880  described  independently  by  Jos.  LeConte 
and  myself,  in  the  auriferous  pliocene  gravel  of  California. 
The  pebbles  of  feldspathic  and  hornblendic  rocks  occur- 
ring in  the  portions  below  drainage-level  —  the  so-called 
blue  gravel  —  are  unaltered,  while  above  that  level  the 
similar  pebbles,  exposed  to  the  action  of  meteoric  waters, 
are  more  or  less  completely  kaolinized,  exfoliating,  becom- 
ing earthy  in  texture,  rusty  in  color,  and  in  some  cases 
converted  into  a  clayey  mass.  The  pjrites,  so  abundant 
in  the  blue  gravel,  has,  in  these  uppc*  portions,  or  so- 
called  red  gravely  been  oxydized,  and  the  accompanying 
lignites  have  been  silicified,  and  often  incrusted  with 
crystallized  quartz,  from  silica  liberated  in  the  process  of 
rock-decay  through  the  infiltration  of  surface-waters.f 

§  43.   To  the  porosity  of  the  gravel,  and  the  great 

*  Geology  of  Canada,  p.  896. 

t  LeConte,  Amer.  Jour.  Science,  xix.,  177;  Hunt,  ibid.,  xix.,  371. 


VII.] 


THE  DECAY  OP  CRYSTALLINE   ROCKS. 


273 


amount  of  surface  thus  exposed,  is  to  be  added  the  influ- 
ence of  carbonic  acid  from  the  decaying  lignite,  the 
carbon  of  which  is  oxydized  as  the  process  of  silicifi cation 
goes  on.  The  amount  of  carbonic  dioxyd  in  the  air  of 
certain  drift-mines  in  these  auriferous  gravels  is  so  great 
that  candles  will  not  burn  therein.  Mr.  D.  T.  Hughes  of 
San  Francisco,  a  well  known  mining  engineer,  to  whose 
careful  scientific  observations  I  have  been  much  indebted, 
informs  me  that  in  the  case  of  a  drift-mine  300  feet  below 
the  surface,  in  Table  Mountain,  Tuolumne  County,  Cali- 
fornia, where  the  foulness  of  the  air  was  especially 
remarked,  he  satisfied  himself,  by  appropriate  tests,  of  the 
presence  in  the  air  of  a  large  proportion  of  carbonic 
dioxyd.  If,  as  there  is  reason  to  suppose,  the  amount  of 
this  element  in  our  atmosphere  was  somewhat  greater  in 
former  ages  than  at  present,  we  have  in  these  gravels  an 
illustration  of  its  influence  in  promoting  the  docay  of  sili- 
cated  rocks.  It  is  not  improbable  that  the  sulphuric  acid 
generated  by  the  oxydation  of  the  pyrites  present  in  these 
gravels  may  also  have  aided  in  the  process. 

§  44.  The  slight  evidences  of  decomposition  to  be  seen 
in  the  crystalline  rocks  of  thoroughly  glaciated  regions, 
as  well  as  in  transported  boulders,  make  it  probable 
that  the  seemingly  rapid  progress  of  decay,  occasionally 
observed  on  exposure,  of  similar  rocks  in  other  regions, 
sometimes  appealed  to  as  evidence  of  a  decomposition 
now  going  on,  is  really  but  the  mechanical  disintegration 
of  masses  already  partially  kaolinized  in  former  ages. 
The.  crumbling  of  certain  apparently  unaltered  granitoid 
rocks,  in  which  the  feldspar  remains  bright  and  hard, 
should  be  distinguished  from  that  which  follows  chemical 
decomposition.  Such  disintegration,  due  apparently  to 
changes  of  temperature  *  and  the  action  of  frost,  is,  how- 

*  In  this  connection  I  venture  to  recall  the  attention  ci  geologists  to  a 
phenomenon  already  described  both  by  Dr.  Shaler  and  myself,  apparently 
due  to  superficial  alternations  of  temperature  on  certain  crystalline  rocks, 
which  have  resulted  'n  establishing  in  them,  to  a  considerable  depth,  a 


W  ''il 


iff  I-'     1 1 


!       I 


274 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


[VII. 


"■'  ffiilli 


ever,  important,  and  deserves  farther  study  from  the  fact 
that  materials  apparently  of  similar  origin  enter  into  the 
composition  of  many  derived  rocks.  Lava-flows  are,  it 
has  been  observed,  subject  to  comparatively  rapid  sub- 
aerial  decay,  but  these  rock-surfaces  differ  widely  in  tex- 
ture, as  well  as  in  composition,  from  most  crystalline 
rocks. 

§  45.  An  essay  by  Professor  Pumpelly  on  Secular 
Rock-Disintegration,  read  before  the  National  Academy 
of  Sciences,  in  April,  1878,*  is  a  very  valuable  contribu- 
tion to  the  subject  before  us.  He  cites  therein  my  conclu- 
sions as  to  the  great  antiquity  and  the  universality  of  the 
process  of  rock-decay  (to  which  his  own  observations  in 
Missouri  have  contributed  importf'.nt  data),  and  also  as 
to  the  final  removal  of  decomposed  material  from  north- 
eastern America  in  the  time  of  the  glacial  drift.  He  fur- 
ther notes  the  little  attention  hitherto  given  to  the  subject 
of  sub-aerial  decay,  and  points  out  its  importance  in  con- 
nection with  great  problems  in  dynamical  geology.  The 
view  that  this  process  of  rock-decay  is  "a  necessary  pre- 
liminary to  glacial  and  erosi^'e  acdon,  which  removed 
already  softened  materials,"  receives  from  Professor  Pum- 
pelly an  extended  discussion  and  application.  He  pro- 
cc-tds  to  consider  the  removal  and  the  re-arrangement  of 
these  softened  materials  by  three  different  agencies. 
First,  the  encroachment  of  the  sea  upon  a  subsiding  region 
of  decayed  rocks ;  second  the  aci/ion  of  land-glaciers,  in 
which  he  points  out  that  the  groat  mass  of  disintegrated 
and  water-impregnated  rock  wculd  become  frozen,  and 

series  of  lifts  or  divisional  planes  parallel  to  the  present  surface,  which 
are  well  known  to  quarrymen.  Instances  of  this  abound ;  besides  those 
noticed  by  me  in  the  Araer.  Jour.  Science  for  July,  1870  (vol.  i.,  p.  80), 
may  be  mentioned  the  gneiss  on  the  opposite  slopes  of  Rollestou  Hill, 
Fitclibuig,  MassacLviSetcs,  and  that  of  Stone  Mountain,  near  Atlanta, 
Georgia;  also  a  remarkable  example  of  comparatively  thin  horizontal 
plates  at  the  outcrop  of  beds  cf  nearly  veriical  micacejus  gneiss  in  the 
vicinily  of  Worcester,  Massachusetts.  '  . 

*  Amer.  Jour.  Science,  xvii.,  133-144. 


I' 


vn.j 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


276 


t 
)- 
IC- 

\e 

Lar 

my 

bu- 

jlu- 

the 

isin 

0  as 
orth- 
}  f  ur- 
ibject 

1  con- 
Tbe 

y  p^^: 

noved 
Pum- 
e  pro- 
ent  oi 
encies. 

lievs,  ii^ 
jegra 
in,  a 


ted 
nd 


Lee,  -which 
[ides  those 
i.,  ?•  8«V 

ir  Atlanta, 
]borizonta\ 
leiss  in  the 


included,  as  it  were,  in  the  glacier,  sharing  in  its  move- 
ments and  forming  thus  a  ground-moraine.* 

§  46.  To  these  modes,  with  which  are  to  be  included 
the  ordinary  action  of  rivers  and  floods,  all  acting  on  the 
peripheral  areas  of  continents,  he  adds,  for  the  central 
areas,  removed  from  these  agencies,  and  rendered  desert 
by  geographical  conditions,  the  action  of  the  winds.  By 
these  the  decayed  rock,  according  to  Pumpelly's  extension 
of  the  ingenious  hypothesis  of  Richthofen,  will  be  sepa- 
rated into  the  fine  material  of  the  loess,  on  the  one  hand, 
and  the  sand  and  gravel  of  the  desert  steppes  on  the 
other.  He  thus  explains  the  condition  of  the  crystalline 
rocks  in  northern  Asia,  from  which  the  decayed  mantle 
has  been  removed  not  by  glacial  'but  by  aerial  agencies ; 
while  the  similar  rocks  in  southern  Asia,  as  in  Brazil  and 
the  southern  United  States,  are  still  deeply  covered  with 
the  products  of  their  own  decomposition. 

§  47.  Pumpeiiy  farther  remarks  that  the  surface  of  the 
undecayed  rock  to  be  laid  bare  by  erosion  is  ijecessarily 
an  irregular  one,  the  inequalities  depending  not  upon  its 
original  difference!  in  hardness,  but  upon  its  resistance  to 
decay  under  the  influence  of  atmospheric  waters.  The 
effect  of  fractures,  joints,  veins,  and  dikes  in  the  rock,  in 
favoring  or  retarding  the  action  of  this  agent,  would  be 
manifested  by  still  further  irregularities  of  the  plane  limit- 
ing the  decomposition  of  the  rock  in  depth.     Thus  the 

*  Other  agencies  than  ice  may  produce  a  similar  displacement  of 
decayed  material.  Belt,  in  1874,  in  his  Naturalist  in  Nicaragua  (page  94), 
describes  a  movement  of  the  mantle  of  decayed  crystalline  rock  on  hill- 
sides, in  that  country,  as  due  to  land-slides  in  wet  weather.  The  layer  of 
ground  and  "  reworked  "  decayed  material  resting  on  the  gneiss,  found  by 
Hartt  in  Brazil  (Scientific  Results  of  a  Journey,  etc.,  pp.  28,  573),  and 
referred  by  him  to  glaciation,  may  perhaps  be  a  similar  phenomenon. 
More  recently,  Kerr,  in  1879,  has  described  the  results  of  a  slow  down- 
ward motion  of  the  decomposed  surface  on  mouni,ain-sides  in  North 
Carolina  as  due  to  the  alternate  freezing  and  thawing  of  the  contained 
water.  To  tliis  displaced  and  modified  layer,  which  resembles  that  pro- 
duced by  glacial  action,  he  gives  the  name  of  frost-drift  (Proc.  Amer. 
Inst.  Mining  Engineers,  viii.,  402.) 


1^ 


276 


THE  DECAY  OF  CRYSTALLINE  ROCKS. 


[VII. 


rounded  surfaces,  and  the  closed  rock-basins,  so  often 
observed  in  glaciated  regions  of  crystalline  rocks,  are 
seen  to  be  but  the  natural  results  of  the  process  of 
rock-decay,  which  preceded  and  prepared  the  way  for 
denudation. 

§  48.  Similar  views  as  to  glacial  erosion  have  since 
been  advocated  by  Nathorst,  and  more  lately  by  Reusch, 
wlio,  in  a  memoir  on  the  geology  of  Corsica,  presented  to 
the  Geological  Society  of  France,  in  November,  1882,* 
has  described  the  disintegration  of  the  granitic  region  of 
Corsica  to  a  depth  of  several  metres,  giving  to  the  surface 
smooth  slopes,  instead  of  the  bold  escarpments  seen  in  like 
rocks  in  Scandinavia.  He  notes  in  these  disintegrated 
rocks  in  Corsica,  enclosed  balls  or  ellipsoidal  masses,  fresh 
in  appearance,  but  like  in  composition  and  in  structure  to 
the  enclosing  rock,  which,  when  detached,  have  been 
taken  for  erratic  blocks.  With  this  region  he  contrasts 
the  similar  rocks  near  Christiania,  in  Norway,  with  hard, 
rounded  surfaces,  marked  by  glacial  scratches,  where  it  is 
difficult  to  find  any  trace  of  superficial  decay.  He  does 
not  believe  that  the  ice  of  the  glacial  period  removed  any 
considerable  portion  of  the  hard  rock,  to  form  fiords,  val- 
leys, etc.,  but  supposes  "  a  profound  disintegration  of  the 
Scandinavian  rocks  before  the  glacial  period,"  and  con- 
ceives the  present  relief  to  "  represent  the  surface  of  the 
unaltered  syenite  after  the  removal  by  the  glaciers  of  all 
the  decomposed  part." 

The  salient  rock-masses  of  the  Norwegian  coast  are, 
like  the  fiords,  arranged  in  a  north  and  south  direction, 
and  this,  according  to  Reusch,  corresponds  with  that 
of  fissures,  more  or  less  nearly  vertical,  which  traverse  the 
rock,  and,  as  he  well  remarks,  prepared  the  way  for  its 
disintegration  in  depth,  the  extent  of  which  would  depend 
upon  differences  in  the  nature  of  the  rock.  Many  of  the 
lake-basins  of  this  region  were,  in  his  opinion,  formed 
through  the  removal  by  glaciers  of  the  decayed  material 
*  Bull.  Soc.  Geol.  de  France,  xi.,  62-67. 


i&.  - 


VII.] 


THE  DECAY   OF  CRYSTALLINE   ROCKS. 


277 


from  depressions,  while  others  are  due  to  the  action  of 
moraines,  serving  as  dikes. 

§  49.  It  is  difficult  to  state  more  clearly  the  conse- 
quences which  follow  from  the  conception  that  the  decom- 
position of  rocks  is  "a  necessary  preliminary  to  glacial 
action  and  erosion,  which  removed  previously  softened 
materials."  Reusch,  however,  seems,  from  some  miscon- 
ception, to  regard  this  pre-glacial  disintegration  of  the 
rocks  as  distinct  from  kaolinization,  of  which  the  crum- 
bling of  the  granites  in  Corsica,  as  in  other  regions,  doubt- 
less represents  an  incipient  stage,  such  as  we  meet  with 
in  regions  where  the  superficial,  and  more  completely 
decayed  portions,  have  been  removed  (§  44). 

§  50.  The  points  insisted  upon  in  this  essay  may  be 
thus  briefly  resumed :  — 

1.  The  evidence  afforded  by  recent  geological  studies 
in  America,  and  elsewhere,  of  the  universality  and  anti- 
quity of  the  sub-aerial  decay  both  of  silicated  crystalline 
rocks  and  of  calcareous  rocks,  and  of  its  great  extent  in 
pre-Cambrian  times. 

2.  The  fact  that  the  materials  resulting  from  this 
decay  are  preserved  in  situ  in  regions  where  they  have 
been  protected  from  denudation  by  overlying  strata,  alike 
of  Cambrian  and  of  more  recent  periods;  or,  in  the 
absence  of  these  coverings,  by  the  position  of  the  decayed 
materials  with  reference  to  denuding  agents,  as  in  driftless 
regions,  or  in  places  sheltered  from  erosion,  as  in  the 
Appalachian  and  St.  Lawrence  valleys. 

3.  That  this  process  of  decay,  though  continuous 
through  later  geological  ages,  has,  under  ordinary  condi- 
tions, been  insignificant  in  amount  since  the  glacial  period, 
for  the  reason  that  the  timr  which  has  since  elapsed  is 
small  when  compared  with  previous  periods,  and  also, 
probably,  on  account  of  changed  atmospheric  conditions  in 
the  later  time. 

4.  That  this  piocess  of  decay  has  furnished  the  mate- 
rials not  only  for  the  clays,  sands,  and  iron-oxyds  from  the 


Ik 


278 


THE  DECAY   OF  CRYSTALLINE  ROCKS. 


[VII. 


beginning  of  paleozoic  time  to  the  present,  but  also  for 
the  corresponding  rocks  of  eozoic  time,  which  have  been 
formed  from  the  older  feldspathic  rocks  by  the  partial  loss 
of  protoxyd-bases.  The  bases  thus  separated  from  crys- 
talline silicated  rocks  have  been  the  source,  directly  and 
indirectly,  of  most  limestones  and  carbonated  rocks,  and 
have,  moreover,  caused  profound  secular  changes  in  the 
constitution  of  the  ocean's  waters.  The  decay  of  sul- 
phuretted ores  in  the  eozoic  rocks  has  given  rise  to  oxy- 
dized  iron-ores,  and  also  to  deposits  of  rich  copper-ores,  in 
various  geological  horizons. 

5.  That  the  rounded  masses  of  crystalline  rock  left  in 
the  process  of  decay  constitute  not  only  the  boulders  of 
the  drift,  but,  judging  from  analogy,  the  similar  masses  in 
conglomerates  of  various  ages,  going  back  to  eozoic  time  ; 
and  that  not  only  the  forms  of  these  detached  masses,  but 
the  outlines  of  eroded  regions  of  crystalline  rocks,  were 
determined  by  the  preceding  process  of  sub-aerial  decay  of 
these  rocks. 


m 


VIII. 

A  NATURAL  SYSTEM  IN  MINERALOGY. 

This  essay  was  presented  in  abstract  to  the  National  Academy  of  Sciences,  in 
Washington,  April  23. 1885,  and  subsequently  to  the  Royal  Society  of  Canada,  in 
Ottawa,  May  27, 1886.  It  is  published  in  full  in  the  Transactions  of  the  latter  society, 
vol.  III.,  sec.  iii.;  in  abstract  in  the  American  Naturalist  for  July,  1885;  and  also, 
with  some  farther  additions,  in  the  Canadian  Record  of  Science,  i.,  129-136  and  244-247. 

I.  —  HISTORICAL    INTRODUCTION. 

§  1.  The  examination  of  the  various  species  of  the 
inorganic  kingdom  which  constitute  the  crust  of  the  earth 
has  long  occupied  the  attention  of  students  of  natural 
history,  and  has  given  rise  to  descriptive  and  systematic 
mineralogy.  Botanists  and  zoologists,  by  making  known 
the  structure,  growth,  and  development  of  organic  species, 
have  meanwhile  performs  I  a  similar  task  for  the  vegetable 
and  animal  kingdoms,  and  have,  moreover,  arranged 
organic  species  in  genera,  families,  orders,  and  classes,  in 
such  manner  as  to  show  more  or  less  perfectly  their  origin 
and  affinities,  so  that  to-day  the  received  classifications  of 
plants  and  animals  merit  the  name  of  natural  systems. 

§  2.  Without  adverting  to  the  work  of  earlier  students, 
it  should  be  said  that  Werner,  about  a  century  since,  pro- 
posed for  the  mineral  kingdom  a  classification  which 
makes  an  epoch  in  the  history  of  mineralogy.  His  system 
was  based  on  "  the  natural  alliances  and  differences  which 
exist  between  minerals,"  and  of  him  it  is  said  that  he 
"  established  and  arranged  the  greater  number  of  species 
in  the  mineral  kingdom  solely  by  agreements  and  differ- 
ences in  external  characters ; "  grouping  the  various  mine- 
rals in  classes,  families,  genera,  species,  sub-species,  and 
kinds.     While  chemical   considerations  were   not  over- 


280 


A  NATUIIAL  SYSTEM   IN  MINKBAliOGY. 


tVIIL 


looked  in  the  larger  divisions,  Werner,  according  to  Jame- 
son, regarded  the  intervention  of  chemistry  as  but  a 
provisional  expedient,  and  doubted  tlie  possibility  of  con- 
structing a  philosophical  system  in  which  the  external  and 
the  chemical  characters  sliould  be  conjoined. 

§  3.  Werner  died  in  1817,  and  was  succeeded  at  Frei- 
berg by  Frederick  Mohs,  who  sought  to  complete  tlie  work 
of  his  great  predecessor  in  mineralogy.  His  early  publica- 
tions on  mineral  classification  go  back  to  1805,  but  it  was 
not  till  1822-24  that  he  gave  to  the  world  his  "  Grundriss 
der  Mineralogie,"  in  two  volumes.  This  was  translated 
into  English,  with  additions,  by  one  afterwards  famous  in 
science,  William  Haidinger,  who  declared,  in  the  preface  to 
that  translation,  published  in  Edinburgh  in  1825,  that  he 
had  been  a  student  in  mineralogy  with  Mohs  since  1812. 

Previous  to  1820,  however,  Mohs  had  visited  Edin- 
burgh, and  had  there  aided  Jameson,  then  preparing  the 
third  edition  of  his  "  System  of  Mineralogy,"  which  ap- 
peared in  three  volumes  in  Edinburgh  in  1820.  In  his 
preface  to  this  edition,  Jameson  gratefully  acknowledges 
his  aid,  and  says  that  the  arrangement  adopted  "  is  nearly 
that  of  my  celebrated  friend,  Mohs,  who  now  fills  the 
mineralogical  chair  of  the  illustrious  Werner."  He  adds, 
"  The  mineral  system,  as  it  appears  in  this  work,  is  to  be 
considered  as  realizing  those  views  which  Werner  enter- 
tained in  regard  to  the  mode  of  arranging  and  determining 
minerals."  This  system,  which  was  designated  by  Jame- 
son the  Natural  History  Method,  is,  according  to  him, 
"founded  on  what  are  popularly  called  external  charac- 
ters, and  is  totally  independent  of  any  aid  from  chemis- 
try." It  was,  moreover,  in  his  opinion,  the  only  method 
"  by  which  minerals  would  be  scientifically  arranged  and 
rightly  determined."  * 

*  For  a  further  notice  of  Werner's  views  of  mineral  classification,  the 
reader  is  referred  to  the  preface  to  Jameson's  worlt,  already  cited,  and 
also  to  Cleveland's  Treatise  on  Mineralogy  and  Geology,  in  1822,  where, 
in  vol.  i.,  pp.  77-83,  will  be  found  an  excellent  analysis  of  Werner's  min- 
eralogical system,  as  put  forth  by  him  at  Freiberg  in  1816. 


■"i ;! 


VIII.] 


A  NATURAL  SYSTEM  IN  MINEUALOGY. 


281 


§  4.  The  system  of  Mohs  at  once  found  favor  witli 
naturalists,  and  was  adopted  by  many  (notably  by  his 
successor,  Breithaupt),  not,  however,  without  certain 
modifications  as  to  the  divisions,  some  of  wliicli  may  here 
be  noticed,  in  order  to  give  a  general  idea  of  the  plan  of 
classification.*  In  the  order  Spar,  as  defined  by  Mohs, 
were  included  not  only  all  zeolites,  scapolites,  and  feld- 
spars, with  sodalite,  nephelite,  and  leucite,  but  petalite, 
spodumene,  and  cyanite,  as  well  as  pyroxene,  amphibole, 
wollastonite,  and  epidote,  the  latter  four  being  made  si)e- 
cies  of  one  genus,  Augite-Spar  (§  48).  Again,  in  the 
order  Gem  of  Mohs  we  find  garnet,  idocrase,  and  stauro- 
lite  grouped  together  as  species  of  the  genus  Garnet ; 
chrysolite,  axinite,  emerald,  tourmaline,  topaz,  andalusite, 
and  zircon,  types  of  as  many  genera;  together  with  the 
genus  Quartz^  including  the  species  iolite,  quartz,  and 
opal.  Corundum,  chrysoberyl,  and  spinel  are  also  united 
in  one  genus,  and  boraoite  and  diamond  constitute  other 
genera  under  this  order. 

§  5.  In  adopting  the  system  of  Mohs,  Charles  Uphara 
Shepard  sub-divided  the  order  Spar,  and  established  a 
new  order.  Zeolite,  in  which  were  included  with  the 
zeolites,  sodalite,  nepheline,  and  leucite,  the  other  genera 
in  the  order  Spar  of  Mohs  being  left  as  before.  J.  D. 
Dana,  on  the  contrary,  enlarged  this  order,  renamed  by 
him  Chalcinea,  by  adding  t-^  it  a  large  part  of  the  order 
Mica  of  Mohs,  including  all  the  true  micas  then  known. 
He,  on  the  other  hand,  removed  epidote  from  the  alliance 
with  pyroxene,  made  by  Mohs,  and  placed  it  in  its  proper 
position,  with  garnet  and  idocrase,  in  the  order  Gem, 
called  by  Dana  Hyalinea.  This,  for  the  rest,  embraced 
all  the  species  which  had  been  therein  included  by  Mohs, 
whom  Dana  followed  by  placing  cyanite  and  fibrolite  with 
the  Spars,  while  andalusite  was  arranged  with  the  Gems. 

§  6.   Bearing  in  mind  the  changes  just  noted,  we  have 

*  See,  for  the  system  as  modified  by  Weisbach  and  Breithaupt,  §  111, 
note. 


282 


A   NATUKAL  SYSTEM   IN  MINERALOGY. 


IVIII. 


r„   ; 


to  record  that  in  1835  the  classification  and  tlie  nonien- 
clatiire  of  Mohs,  as  tranahited  into  English  by  Haidinger, 
were  adopted  by  Shepard  in  the  first  edition  of  his  "  Treat- 
ise on  Mineralogy."  In  the  second  and  third  editions  of 
this  work,  however,  in  1844  and  1852,  Shepard,  while 
retaining  with  slight  modifications  the  classes  and  orders 
of  Mulis,  abandoned  the  characteristic  specific  names  of 
the  latter  for  the  trivial  names  generally  accepted.  The 
natural-history  system  of  Mohs  was  also  adopted,  in  the 
first  and  second  editions  of  his  "  System  of  Mineralogy," 
by  J.  D.  Dana,  in  1837  and  1844.  He,  however,  devised 
a  Latin  terminology  for  tlie  orders,  as  well  as  a  binomial 
Latin  nomenclature  for  the  genera  and  species. 

§  7.  In  abandoning  the  natural-history  system  in  his 
third  edition,  in  1850,  Dana  returned  to  the  trivial  nomen- 
clature. Referring  to  these  changes,  its  author  declared 
in  the  preface  to  a  fourth  edition  of  his  System,  in  1854, 
his  opinion  that  "  the  system  of  Mohs,  valuable  in  its  day, 
had  s  '^served  its  end,  and  that,  in  throwing  off  its  shack- 
les for  the  more  consistent  principles  flowing  from  recent 
views  on  chemistry,  the  many  difficulties  in  the  way  of 
perfecting  a  new  classification  led  the  author  to  an 
arrangement  which  should  serve  the  convenience  of  the 
student,  without  pretending  to  strict  science." 

A  so-called  "  purely  chemical  mineral  system  "  had  been 
proposed  by  Berzelius  as  early  as  1815,*  and  had  mean- 
while found  favor  with  chemists.  Towards  this,  the 
difficulties  of  the  natural-history  method  in  mineralogy 
directed  Dana,  who,  in  the  preface  to  his  second  edition,  in 
1844,  gave,  "  besides  the  natural  classification,  another, 
placing  the  minerals  under  the  principal  element  in  their 
composition,"  adding  that  "  various  improvements  on  the 
usual  chemical  methods  have  been  introduced,  which  may 
render  it  acceptable  to  those  who  prefer  that  mode  of 
arrangement."  The  chemical  scheme  then  given  by  him 
was,  as  he  informs  us,  taken  almost  entirely  from  Ramuiels- 

*  Berzelius,  Nouveau  Syst^me  de  Mineralogie,  Paris,  1819. 


VIII.] 


A  yATURAL  SYSTEM   IN   MINERALOGY. 


283 


berg's  treatise  on  Chemical  Mineralogy,  then  recently 
published.  In  1850,  in  the  latter  part  of  his  third  edition, 
Dana  put  forth  a  new  chemical  classification,  "  in  which 
the  Berzelian  method  was  coupled  with  crystallography  "  ; 
while  in  his  fourth  edition,  in  1854,  he  maintained  that 
*'  the  classification  of  minerals  must  *^'^w  directly  from  the 
principles  of  chemistry,"  and  accepted  what  he  now  called 
the  Berzelian  system,  which,  as  his  readers  are  aware,  is 
retained  in  his  fifth  and  last  edition,  that  of  1868.  It  is 
also  followed  in  the  "  Text-Book  of  Mineralogy "  of  his 
son,  E.  S.  Dana,  in  1883. 

§  8.  The  views  of  Berzelius,  as  adopted  and  modified 
by  Rammelsberg,  Naumann,  Dana,  and  others,  now  prevail 
among  students  of  mineralogy,  with  whom  the  results  of 
the  chemical  analysis  of  speci  s  are  generally  considered 
as  of  paramount  significance;  while  hardness,  specific 
gravity,  crystalline  form,  and  optical  characters  assume  a 
secondary  value  in  classification,  and  are  regarded  as  im- 
portant chiefly  in  connection  with  determinative  mineral- 
ogy. The  conception  of  a  true  natural  method,  which, 
although  but  partially  understood,  was  at  the  basis  of  the 
system  of  Mobs,  has  been  lost  sight  of;  the  order  which 
the  naturalist  finds  in  the  organic  is  no  longer  apparent  in 
the  inorganic  world,  as  presented  iii  modern  mineralogical 
text-books ;  and  this  state  of  things  has  contributed  not  a 
little  to  the  comparative  neglect  into  which  systematic 
mineralogy  has  of  late  years  fallen. 

As  to  the  complete  divorce  between  physical  and  chemi- 
cal characters  in  the  study  of  mineral  species,  maintained 
by  Werner,  Mohs,  and  his  followers,  there  seems  to  have 
underlaid  it  the  notion  of  framing  a  system  which,  as  in 
botany  and  zoology,  shall  be  available  for  the  purposes  of 
determination  without  the  destruction  of  the  individual. 
It  is  to  be  noted,  however,  that  characters  dependent  upon 
chemical  differences,  such  as  the  presence  or  absence  of 
certain  acids,  alkaloids,  and  groups  uf  essential  oils,  are 
not  without  significance  in  determining  the  natural  affini- 


t  '  i 


A  NATURAL  SYSTEM  IN   MINEUALGOY. 


[VIII. 


iCi- 


m  ■ 


"4\ 


ties  of  plants,  and,  moreover,  that  as  wo  descend  the  scale 
of  being,  from  the  highly  orgiinized  forms  of  the  animal 
an<l  vogetablo  world  to  the  simple  crystal  or  the  ainorphous 
colldid  mass,  the  external  characters  which  serve  to  show 
likeness  and  diflerenco  become  fewer,  and  are  often  ob- 
8(!ure  and  ill-delined.  Again,  a  natnral  system  is  not  one 
subordinate  to  the  end  of  identifying  s[)ecie8,  but  should 
consider  objects  in  all  their  alliances  and  relations.  Such 
a  system,  as  hmg  since  denned  by  John  Ray,  is  one  which 
neither  brings  together  dissimilar  species  nor  separates 
those  which  are  nearly  allied,  and  the  most  important 
resemblances  and  differences  in  the  mineral  kingdom  are, 
in  many  cases,  those  which  can  only  be  determined  by 
chemical  investigation. 

§  9.  If,  however,  we  regard  as  mistaken  those  who  in 
their  search  after  a  natural  system  in  mineralogy  have 
rejected  the  aid  of  chemistry,  it  must  be  said,  on  the  other 
hand,  that  the  chemical  mineralogists  who,  disregarding 
.he  relations  of  density  and  hardness,  or  relegating  them 
to  a  secondary  rank,  build  systems  on  the  results  of  chemi- 
cal analysis,  are  false  to  chemical  science  itself.  There 
exist,  in  fact,  inherent  and  necessary  relations  between  the 
physical  characters  and  the  chemical  constitution  of  inor- 
ganic bodies  which  serve  to  unite  and  reconcile  the  natu- 
ral-historical and  the  chemical  methods  in  mineralogy.  A 
physico-chemical  study  of  the  mineral  kingdom,  having  in 
view  these  relations,  will  enable  us,  while  remaining  faith- 
ful to  the  great  traditions  of  Werner  and  of  Mohs,  to 
frame  a  classification  which  it  is  believed  will  merit  the 
title  of  a  Natural  System  in  Mineralogy. 


II.  —  AN   ATTEMPT   AT   A   NATURAL   SYSTEM. 

§  10.  That  such  a  system  is  possible  was  maintained  by 
the  present  writer  in  a  series  of  papers  published  in  1853, 
1854,  and  1855,  to  be  noticed  in  detail  farther  on.  In 
putting  forth,  in  the  first-named  year,  my  conclusions  as 
to  the  extension  of  chemical  homology,  and  the  similarity 


f 


in 


VlIl.J 


A  NATUUAL  HYHTEM   IN   MINEltALOGV. 


285 


of  volunio  in  isomorphous  species,  it  was  said  that  *'  tiieso 
views  will  be  found  to  enliiige  and  simplify  the  pliin  of 
cheniicjil  science,  and  lead  to  u  correct  niineralogical  sys- 
teuj."  This  aim  was  again  clearly  defineil  in  a  communi- 
cation to  the  French  Academy  of  Sciences  in  18*)3, 
published  in  the  Conipte  l{endu,  and  also,  in  a  translation 
l)y  the  author,  in  the  American  Journal  of  Science,  in  the 
same  year.*  Therein,  while  adverting  to  an  earlier  note 
on  the  same  subject,  which  ap[)eared  in  the  Compte  Rendu 
for  July  9,  1855,  it  was  said  that  the  views  of  polymerism 
in  mineral  species,  and  of  the  coiniection  between  relative 
condensation  or  specific  gravity,  hardness,  and  chemical 
characters  are,  "as  I  have  already  elsewhere  shown,  of 
great  importance  in  mineralogy,  and  will  form  the  basis 
of  a  new  system  of  classification,  which  will  be  at  the 
same  time  chemical  and  natural-historical."  These  early 
papers,  however,  perhaps  from  the  general  and  abstract 
manner  in  which  the  subjects  were  then  treated,  have 
hitherto  received  but  little  attention  either  from  chemists 
or  from  mineralogists. 

§  11.  The  whole  subject  was  again  discussed  in  1867, 
in  an  essay  entitled  "The  Objects  and  Method  of  Mineral- 
ogy," in  which  the  iirgument  of  the  preceding  papers  was 
resumed.  It  was  therein  maintained  that  chemistry  is  to 
mineralogy  what  biotics  is  to  organography ;  that  both 
physics  (or  dynamics)  and  chemistry,  which  together  pre- 
side over  the  genesis  of  inorganic  si)ecies,  must  be  taken 
into  account  in  their  study,  and  that  chemical  characters 
must  be  greatly  depended  upon  in  niineralogical  classifi- 
cation ;  while  it  was  added  that  "  in  its  wider  sense  the 
chemical  history  of  bodies  takes  into  consideration  all 
those  characters  "  upon  which  the  natural-history  system 
is  based.f 

*  Compte  Rendu  de  I'Acad.,  June  29,  1863,  and  Amer.  Jour.  Science, 
xxxvi.,  426-428. 

t  Read  before  the  American  Academy  of  Sciences,  January,  1867, 
and  published  in  the  Amer.  Jour.  Science  of  tlie  same  year,  xliii.  203- 
200  ;  also  in  the  author's  Chemical  and  Geological  Essays,  pp.  453-458. 


'^^i! 


■5!  I 


286 


A  NATURAL  SYSTEM  IN   MINERALOGY. 


[VIII. 


§  12.  After  discussing  in  this  connection  the  question 
of  the  densities  of  certain  substances  of  high  equivalent, 
or  molecular  weight,  alike  in  vapor  and  in  liquid  and  solid 
forms,  it  was  said  :  '^  Starting  from  these  high  equivalent 
weights  of  liquid  and  solid  hydrocarbonaceous  species,  and 
their  correspondingly  complex  formulas,  we  are  prepared 
to  admit  that  other  orders  of  mineral  species,  such  as 
oxyds,  silicates,  carbonates,  and  sulphids,  have  formulas 
and  equivalent  weights  corresponding  to  their  still  higher 
densities ;  and  we  proceed  to  apply  to  these  bodies  the 
laws  of  substitution,  homology,  and  polymerism,  which 
have  ao  long  been  recognized  in  the  chemical  study  of 
the  members  of  the  hydrocarbon  series.  The  formulas 
thus  deduced  for  the  native  silicates  and  carbon-spars  show 
that  these  polybasic  salts  may  contain  many  atoms  of  dif- 
ferent bases,  and  their  frequently  complex  and  varying 
constitution  is  thus  rendered  intelligible.  In  the  applica- 
tion of  the  principle  of  chemical  homology  we  find  a  ready 
and  natural  explanation  of  those  variations,  within  certain 
limits,  occasionally  met  with  in  the  composition  of  certain 
crystalline  silicates,  sulphids,  etc.  ;  from  which  some  have 
conjectured  the  existence  of  a  deviation  from  the  law  of 
definite  proportions  in  what  is  only  an  expression  of  that 
law  in  a  higher  form.  The  principle  of  polymerism  is  ex- 
emplified in  related  mineral  species,  such  as  meionite  and 
zoisite,.dipyre  and  jadeite,  hornblende  and  pyroxene,  cal- 
cite  and  aragonite,  opal  and  quartz,  in  the  zircons  of 
different  densities,  and  in  the  various  forms  of  titanic 
oxyd  and  of  carbon,  whose  relations  become  at  once  intelli- 
gible if  we  adopt  for  these  species  high  equivalent  weights 
and  complex  molecules.  The  hardness  of  these  isomeric 
or  allotropic  species,  and  their  indifference  to  chemical  re- 
agents, increase  with  their  condensation  r>r,  in  other  words, 
vary  inversely  as  their  empirical  equivalent  volumes ;  so 
that  we  here  find  a  direct  relation  between  chemical  and 
physical  properties.  .  .  . 

§  13.   "Chemical  change  implies  disorganization,  and  all 


■i-m 


I '  ill 
i 


VIII.] 


A   NATURAL  SYSTEM  IN   MINERALOGY. 


287 


so-called  cheniical  species  are  inorganic  that  is  to  sa}',  un- 
organized, and  hence  really  belong  to  the  mineral  kingdom. 
In  i/his  extended  sense,  mineralogy  takes  in  not  only  the 
few  metals,  oxyds,  sulphids,  silicates,  and  other  salts  which 
aie  found  in  nature,  but  also  all  those  which  are  the  pro- 
ducts of  the  chemist's  skill.  It  embraces  not  only  the  few 
native  resins  and  hydrocarbons,  but  all  the  bodies  of  the 
carbon  series  made  known  by  the  researches  of  modern 
chemistry.  The  primary  object  of  a  natural  classification, 
it  must  be  remembered,  is  not,  like  that  of  an  artificial 
system,  to  serve  the  purpose  of  determining  species,  or 
the  convenience  of  the  student ;  but  so  to  arrange  bodies 
in  orders,  genera,  and  species,  as  to  satisfy  most  thoroughly 
natural  affinities.  Such  a  classification  in  mineralogy  will 
be  based  upon  a  consideration  of  all  the  physical  and 
chemical  relations  of  bodies,  and  will  enable  us  to  see  that 
the  various  properties  of  a  species  iire  not  so  many  arbi- 
trary signs,  but  the  necessary  results  of  its  constitution. 
It  will  give  for  the  mineral  kingdom  what  the  labors  of 
great  naturalists  have  already  nearly  attained  for  the  vege- 
table and  animal  kingdoms. 

§  14.  "In  approaching  this  great  problem  of  classifi- 
cation, we  have  to  examine,  first,  the  physical  conditions 
and  relations  of  each  species,  considered  with  relation  to 
gravity,  cohesion,  light,  heat,  electricity,  and  magnetism ; 
secondly,  the  chemical  history  of  the  species,  in  which  are 
to  be  considered  its  nature,  as  elemental  or  compound,  its 
chemical  relations  to  other  species,  and  these  relations  as 
modified  by  physical  conditions  and  forces.  The  quanti- 
tative relation  of  one  mineral  (chemical)  species  to  an- 
other is  its  equivalent  weight,  and  the  chemical  species, 
until  it  attains  to  individuality  in  the  crystal,  is  essentially 
quantitative.  It  is  from  all  the  above  data,  which  would 
include  the  whole  physical  and  chemical  history  of  inor- 
ganic bodies,  that  a  natural  system  of  mineralogical  classi- 
fication is  to  be  built  up.  .  .  .  The  variable  relations  to 
space  of  the  empirical  equivalents  of  non-gaseous  species. 


tiUH 


288 


A   NATURAL  SYSTEM  IN  MINEUALOUY. 


[VIII. 


i  ■  r    i ' 


or,  in  other  words,  the  varying  equivalent  volumes  (ob- 
tained by  dividing  their  empirical  equivalent  weights  by 
the  specific  gravity),  show  that  there  exist  in  different 
species  very  unlike  degrees  of  coiKhmsation.  At  the 
same  time,  we  are  led  to  the  conclusion  that  the  molecular 
constitution  of  gems,  spars,  and  ores,  is  such  that  tliose 
bodies  mast  be  represented  by  formuiit.  not  less  complex, 
and  with  equivalent  weights  far  more  elevated  than  those 
usually  assigned  to  the  polycyanids,  the  alkaloids,  and  the 
proximate  principles  of  plants.  To  similar  conclusions 
conduce  also  the  researches  on  the  specific  heat  of  com- 
pounds." In  the  paper,  published  in  18G7,  from  which 
the  above  extracts  are  taken,  it  was  farther  said  that  the 
views  there  set  forth  as  "  the  basis  of  a  true  mineralogical 
classification "  were  not  new,  but  had  been  brought  for- 
ward and  maintained  by  the  author  in  various  publications 
from  1853. 

§  15.  The  starting-point  in  this  inquiry  was  the  study 
of  the  chemistry  of  carbon.  It  was  in  1852  that  I  wrote, 
"  We  may  define  organic  chemistry  as  the  chemistry  of  the 
compounds  of  carbon,"  *  ?.  statement  which,  though  a 
common-place  to-day,  was  then  perhaps  made  for  the  first 
time.  I  then  insisted  upon  what  I  called  "the  carbon 
series "  and  "  the  silicon  series,"  the  latter  including  all 
the  known  silicon  compounds.  This  was  followed  in  1853 
by  an  essay  on  "  The  Theory  of  Chemical  Changes  and 
Equivalent  Volumes,"  t  wherein  the  question  of  equiva- 
lent or  so-called  atomic  volumes  was  discussed  with  rela- 
tion to  the,  investigations  of  Playfair  and  Joule,  and  the 
speculations  of  Dana.  It  was  then  and  there  suggested 
that  "  all  species  crystallizing  in  the  same  shape  have  the 
same  equivalent  volume,  so  that  their  equivalent  weights 

*  Essay  on  Organic  Cbemistry,  forming  part  iv.  of  the  Principles  of 
Chemistry  by  B,  Silliman;  3rd  revised  edition,  1852,  p.  378. 

t  Amer.  Jour.  Science,  March,  1853  (xv.,  226-2.34);  L.,  E.  &  D.  "Philos. 
Mag.  (4),  v.,  520,  and  in  a  German  translation  in  the  Cheraisches  Central- 
blatt  of  Leipsic  for  the  same  year  (p.  849);  also  in  the  author's  Chem.  and 
Geol.  Essays,  pp.  427-437. 


l«. 


mi. 


VIII.] 


A  NATURAL   SYSTEM  IN  MINEKALOGY. 


289 


^ob- 


iby 

rent 

the 

those 

iplex, 

those 

id  the 

Lisions 

•  com- 

which 

lat  the 

ilogical 

;ht  for- 

Lcations 


(as  in  the  case  of  vapors)  are  directly  as  their  densities, 
and  the  equivalents  of  mineral  species  are  as  much  more 
elevated  than  those  of  the  carbon  series  as  the  specific 
gravities  are  liigher." 

§  16.  Another  principle  there  set  forth  was  the  general 
application  of  the  law  of  progressive  or  homologous  series, 
first  enunciated  in  1842  by  James  Schiel  of  St.  Louis,  and 
soon  afterwards  adopted  by  Ch.  Gerha.dt,  but  hitherto 
applied  only  to  hydrocarbonaceous  or  so-called  organic 
species.  It  was  now  said  that  "  it  may  be  expected  that 
mineral  species  will  exhibit  the  same  relations  as  those  of 
the  carbon  series,  and  the  principle  of  homology  be  gn^atly 
extended  in  its  application.  The  history  of  mineral  species 
affords  many  instances  of  isomorphous  silicates  whose 
formulas  differ  by  WO2M2,  as  the  tourmalines,  and  the 
silicates  of  alumina  and  magnesia ;  while  the  latter,  with 
many  zeolites,  exhibit  a  similar  difference  of  WO2H2  [O  in 
these  formulas  =  8].  The  relation  is  in  fact  that  which 
exists  between  neutral,  surbasic,  and  hydrated  salts."  It 
was  further  declared  that  the  carbon-spars  must  be  repre- 
sented as  polycarbonates,  having  not  less  than  from 
"  twelve  to  eighteen  equivalents  of  base  replaceable  so  as 
to  give  rise  to  a  great  number  of  species " ;  while  the 
variations  in  the  calculated  atomic  volumes  of  these  car- 
bonates were  said  to  "indicate  the  existence  of  several 
homologous  genera,  which  are  isomorphous." 

§  17.  These  conceptions  of  progressive  series  of  more 
or  less  highly  condensed  molecules  of  polycarbonates  and 
polysilicates,  and  of  similai'ity  of  volume  for  isomorphous 
species,  were  developed  more  at  length  in  a  second  paper 
published  in  the  same  year,  1853,  on  "The  Constitution 
and  Equivalent  Volume  of  Mineral  Species."  *  It  was 
therein  explained  that  the  formulas  of  homologous  bodies 
may  be  represented  as  series  in  arithmetical  progression, 
in  which  the  first  term  may  be  either  like  or  unlike  the 

*  Anier.  Jour.  Science,  1853  (xvi.,  203-218),  and,  in  abstract,  in  the 
author's  Chem.  and  Geol.  Essays,  p.  438,  etc. 


290 


A  NATURAL   SYSTEM  IN   MINEKALOGY. 


IVIII. 


i!(ili 


common  difference ;  both  cases  being,  it  was  shown,  illus- 
trated in  the  chemical  history  of  mineral  species,  in- 
cluding carbonates,  silicates,  and  oxyds.  Similar  views 
were  also  then  extended  to  nitrates  and  sulphates,  as  well 
as  to  chlorids  and  to  sulphids. 

The  simplest  atomic  formula  of  the  carbonates  being 
CMO3  (C  =  6  and  0  =  8,  according  to  the  molecular 
weights  then  in  use),  the  rhombohedral  carbon-spars  were 
referred  to  three  genera  represented  by  ^(CMOa),  namely: 
(1)  calcite,  w  =  30 ;  (2)  dolomite,  siderite,  and  diallogite, 
w  =  36;  and  (3)  smithsonite  and  magnesite,  w  =  40.  For 
the  prismatic  species,  aragonite,  like  calcite,  belonged  to 
a  genus  with  w  =  30 ;  while  for  strontianite,  cerusite,  and 
bromlite,  n=  25 ;  and  for  witherite  n  =  22.  The  volumes 
of  the  rhombohedral  species  deduced  from  these  formulas 
were  from  550  to  560,  and  for  the  prismatic  species  from 
500  to  510.  These  arbitrary  molecular  weights  and  vol- 
umes were,  at  the  time,  supported  by  comparisons  with 
those  deduced  from  the  formulas  of  the  rhombohedral 
red-silver  ores  and  the  prismatic  bournonite,  and  farther 
by  the  volume  of  the  compound  of  glucose  and  sodium- 
chlorid,  regarded  as  homoeomorphous  with  calcite,  with  a 
density  of  1.563,  which,  doubling  its  empirical  formula, 
gave  a  volume  of  558.5.  The  various  alums,  if  their  for- 
mulas be  doubled,  give  in  like  manner,  as  was  shown,  vol- 
umes of  from  543  to  561. 

§  18.  Extending  to  the  silicates  the  same  notion  of 
polynierism  which  had  just  been  applied  to  the  carbon- 
ates, the  existence  of  various  polysilicates  was  admitted. 
Thus  the  formulas  of  spodumene,  diopside,  hudsonite,  and 
woUastonite  were  described  as  pr»  anting  a  homologous 
series  of  the  first  kind,  in  which  the  first  term  is  the  same 
as  the  common  difference,  "represented  by  ^(SiaMOa), 
the  respective  values  of  n  being  30,  26,  24,  and  22." 
Spodumene  was  then,  chiefly  on  crystallographic 
grounds,  compared  with  the  pyroxenes.  The  excess  of 
silica  above  the  bisilicate  ratio,  met  with  in  some  amphi- 


VIII.] 


A   NATURAL  SYSTEM   IN   MINERALOGY. 


291 


boles,  was  referred  to  as  an  example  of  a  homology  of  the 
second  kind,  in  which  the  common  difference  is  unlike  the 
first  term.  To  these  species  there  was  assigned  an  equiv- 
alent volume  approximating  to  460.  In  support  of  this 
vt)lume  it  was  noted  that  the  various  orthophosphates  and 
ortharseniates  of  sodium,  with  I2H2O  have,  according  to 
Playfair  and  Joule,  equivalent  volumes  of  from  233  to  235, 
while  ferrocyanid  of  potassium  gives  230,  lactose  234,  and 
piperine  (with  a  density  of  1.244)  476,  or  about  double 
tiiese  numbers.  Other  species,  as  it  wtis  pointed  out, 
iuive  apparently  an  equivalent  volume  of  430,  and  still 
others  about  200,  or  some  multiple  of  this  number. 
Whether  the  weights  thus  assigned  to  various  silicates 
iuid  carbon-spars  might  represent  their  chemical  equiva- 
lents, or  some  portion  thereof,  they  in  any  case  served  to 
show  the  relative  condensation  of  matter  in  the  different 
s[)ecies  compared. 

§  19.   This  subject  was  continued  a  few  months  later, 
in  a  paper  read  at  Washington   in    May,  1854,   before 
the  American  Association  for  the  Advancement  of  Sci- 
ence, entitled  "Illustrations    of  Chemical   Homology."* 
Therein  were  reviewed  and  re-affirmed  the  teachings  of 
the  two  papers  of  1853,  while  the  principles  of  homology 
were   farther   exemplified,    and   it   was   maintained   that 
homologies  may  exist  alike  between  species  differing  by 
/((M2O2)  and  ^(HaOa),  and  even  between  those  related 
s])ecies  which  differ  in  the  proportion  of  silica,  so  that  the 
liitio  between  silica  and  bases  has  but  a  specific  value, 
it  was  farther  contended  that  the  water  contained  in  a 
jj^i'eat  many  hydrated  species  often  described  as  altered 
silicates,  was  to  be  regarded  as  not  of  subsequent  intro- 
duction, but  an  original  and  essential  element  cf  the  spe- 
cies, as  is  admitted  to  be  the  case  in  the  zeolites. 
§  20.   In  the  second  paper  for  1853  was  considered  the 

*  Proc.  Amer.  Assoc.  Adv.  Science,  1854,  pp.  2.37-247;  also,  in  abstract, 
Atiier.  ,Jour.  Science  for  September  of  the  same  year,  and  noticed,  with 
extracts,  in  tlie  autlior's  Clicm.  and  (Jeol.  Essays,  p.  4:58,  et  seq. 


I,*;- ' 


llllfti 


292 


A   NATURAL   SYSTEM  IN   MINERALOOY. 


[vm. 


question  of  chemical  notation  and  formulas,  which  was 
farther  illustrated  in  the  paper  of  1854.  At  this  time  the 
question  of  the  atomicities  of  the  elements  had  n  ">t  yet 
been  discussed,  and  the  distinction  between  univalent  and 
bivalent  metals,  suggested  by  Cannizaro  in  1858,  was  un- 
recognized. The  symbols  then  used  for  both  of  these 
stood  for  one  atom,  or  for  the  proportion  which  in  the  so- 
called  protoxyds  is  united  with  eight  parts  by  weight  of 
oxygen.  In  sesquioxyds  like  alumina,  however,  recog- 
nizing the  trivalent  character  of  AljO^  (27-|-24),  it  was 
by  the  writer  regarded  as  corresponding  to  three  atoms 
of  oxyd  of  aluminium  =  3alO.  Silica,  which,  following 
Berzelius,  was  then  generally  written  SiOg  (21-|-24), 
became  3siO.  With  this  notation  were  constructed 
atomic  formulas,  the  elements  now  regarded  as  diatomic 
bejng  confounded  with  monatomic  elements,  and,  like 
these,  represented  by  capital  letters.  Thus  the  common 
atomic  formula  for  bisilicates,  as  given  above,  was 
written  ^(sigMOg),  and  spodumene,  w  =  30,  was  made 
si6o06o(al24Li4Na2)03o.  Similar  atomic  formulas  are  still 
employed  in  these  pages,  using,  however,  small  letters  to 
represent  an  atom  of  any  element,  whether  univalent,  like 
sodium  or  chlorine ;  bivalvent,  like  calcium  or  oxygen ; 
trivalent,  like  boron ;  quadrivalent,  like  silicon,  titanium, 
and  carbon;  or  sexvalent,  like  the  double  molecule  of 
aluminium.  The  above  general  formula  is  thus  now 
written  w(sir.mi03),  and  that  given  for  spodumene 
(si6oal24li4na2)o9o.  In  order  to  distinguish  the  atom  of 
ferrosum  =  ^Fe,  from  that  of  ferricum  =  ^Fe,  the  former 
is  written  fe,  and  the  latter  fi,  while  manganicum,  corres- 
ponding to  manganic  sesquioxyd,  is  mni. 

§  21.  The  M  in  the  general  formula  M2O2,  employed  in 
1853,  was  thus  made  to  represent  an  atom  either  of  prot- 
oxyd  or  sesquioxyd,  and  in  1854  a  farther  generalization 
was  attempted.  The  boric,  titanic,  tantalic,  and  niobic  an- 
hydrids  were  reduced  to  the  same  atomic  formula  as  silica, 
and,  moreover,  in  view  of  the  variations  in  the  silica-ratio 


II. 

ras 

bhe 

yet 

and 

un- 

tiese 

B  so- 

\i  of 

ecog- 

t  was 

^toins 

awing 

+■24), 

vucted 

atomic 

d,  like 

ommop 

^e,  was 

g  made 

Lxe  still 

tters  to 

ent,  like 

oxygen ; 
Itanium, 
ecnle  of 
us  now 
lodumene 
atom  of 
e  former 
,  corres- 

iployed  in 

Ir  of  pi'o^ 
jralizati'^'^ 
Iniobic  an- 
la  as  silica, 
Isilica-ratio 


VIII.] 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


293 


in  related  silicates,  like  feldspars,  sc*ipoHtes,  and  micas, 
and  the  supposed  rei)lacement  of  silica  by  alumina  in  cer- 
tain amphiboles,  it  was  suggested  that  the  old  distinction 
of  acid  and  base,  recognized  in  the  dualistic  hypothesis, 
might  be  set  aside.  M,  in  the  generalized  formula  as  then 
written,  n(M02),  would  then  represent  not  only  Na  and 
Ca,  but  al,  si,  b,  ti,  and  ta,  as  well,  and  "to  this  type, 
which  is  also  that  of  the  spinels,  all  silicates  may  be  re- 
ferred, except  a  certain  number  which,  like  eudialyte, 
sodalite,  and  pyrosmalite,  contain  metallic  chlorids; 
hauyne,  nosite,  an'^  lapis-lazuli,  which  contain  sulphates; 
and  cancrinite,  which  holds  a  portion  of  carbonate. 
These  are  respectively  basic  chlorids,  sulphates,  and 
carbonates,  and  are  represented  by  (MaOa)^.  MCI,  by 
(M202)w.  SaMjOg,"  etc.  To  these  should  of  course  be 
added  the  basic  fluorids,  or  oxyfluorids,  like  chondrodite 
and  topaz ;  and  oxysulphids  like  helvite  and  danalite.  It 
was  then  said,  "The  above  formulas  are  intended  to 
involve  no  hypothesis  as  to  the  arrangement  of  the  ele- 
ments, for  in  the  author's  view  each  species  is  an  individ- 
ual, in  which  the  pre-existence  of  different  species  that 
may  be  obtained  by  its  decomposition  cannot  be  asserted." 
The  importance  of  this  notation,  proposed  in  1854,  will  be 
apparent  when  we  come  to  consider  farther  the  question 
of  atomic  volume  in  its  relation  to  mineralogical  classifi- 
cation. 

§  22.  Another  and  an  important  question,  connected 
with  the  complex  constitution  which  had  been  assumed 
for  silicates  and  carbonates,  was  considered  in  the  paper 
now  under  review.  The  high  molecular  weight  assigned 
to  the  polysilicates  admitted  the  presence  therein  of  many 
atoms  of  base,  and  of  partial  replacements ;  while  the 
existence  in  crystalline  species  of  visible  mixtures  of  for- 
eign matters  also  served  to  explain  the  presence  of  small 
portions  of  many  elements  detected  therein  by  chemical 
analysis.  It  had,  however,  become  apparent  that  there 
are  variations  in  composition  which  can  scarcely  be  ex- 


294 


A  NATURAL   SYSTEM  IN  MINEKALOGY. 


tVIlI. 


!iifi:;ii"«fi 


plained  in  either  of  these  ways.  Delesse  had  already 
noticed  that  in  the  homoBomorphous  tiiclinic  feldspars 
the  silica-ratio  appears  to  vary  continuously  between 
albite  and  anorthite,  and  was  disposed  to  regard  the  feld- 
spars intermediate  in  composition  between  these  two  as 
varieties  only.*  Scheerer,  also,  had  in  like  manner  ex- 
pressed the  opinion  that  the  various  feldspars  were  to  be 
regarded  as  combinations  of  anorthite  with  labradorite, 
albite  or  orthoclase,  or  of  labradorite  with  albite.  Yon 
Waltershausen  had,  however,  given  a  more  definite  shape 
to  the  notion  already  in  the  minds  of  chemists,  when,  in 
1853,  he  proposed  to  admit  three  typical  triclinic  feld- 
spars, anorthite,  albite,  and  krablite;  the  latter  a  sup- 
posed highly  silicious  species  with  the  atomic  ratios, 
1:3:  24,  since  generally  regarded  as  a  mixture  of  albite 
with  quartz.  These  three  feldspars,  according  to  him, 
"  alone  have  the  right  to  be  regarded  as  species  in  miner- 
alogy. .  .  .  All  other  feldspars,  labradorite,  andesine,  oli- 
goclase,  etc.,  are  merety  mixtures  of  these,"  and  were 
conceived  by  him  to  be  built  up  "  of  infinitely  small  crys- 
tals of  anorthite  and  krablite,  or  of  anorthite  and 
albite."  f 

§  23.  At  the  time  of  writing,  in  1854,  I  was  ignorant 
of  the  lately  published  conclusions  of  Von  Waltershausen. 
I  had  then  made  an  extended  series  of  analyses  of  these 
feldspars,  from  the  Norian  recks,  and,  rejecting  the  hy- 
pothesis of  Scheerer,  to  which  I  referred,  attempted  to 
give  the  matter  a  more  definite  form  by  pointing  out  that 
anorthite  and  albite  might  be  represented  by  a  common 
formula,  which,  if  a  molecular  volume  of  about  402  were 
assigned,  would  be  32(M202)  ;  the  two  polysilicates  being 
respectively,  in  the  atomic  notation  adopted,  (sigiala^Cag) 

*  Delesse,  Ann.  des  Mines,  1853  (5)  iii.,  376.  Scheerer,  Pogg.  Ann. 
Ixxxix.,  19,  cited  in  L.  and  K.  Jahresbcriclit  for  1853,  p.  105. 

t  Sartorius  von  Waltersliausen,  Uber  die  Vullcanisclien  Gesteine  in 
Sicilien  und  Island,  GiJttingen,  1853.  For  this  reference,  and  for  other 
notes  on  the  literature  of  this  question,  I  am  indebted  to  my  friend, 
Dr.  G.  F.  Becker. 


1. 


VUI.J 


A   NATUKAL  SYSTEM  IN   MlNEltALOGY. 


296 


,V3 

en 

Id- 
as 

ex- 
be 

lite, 

Von 

inipe 

n,  iu 

feia- 

sup- 
atios. 
albite 
,  him, 
miner- 
ne,  oU- 
{  were 
,11  crys- 
be    n^nd 

rnovant 
^bauiscn. 
;{  tbese 
the  by- 
mted  to 
out  tbat 
jcommon 
t02  were 
ies  being 
Ig^aliMCas) 

•ogg.  An«- 

Jtesteine  i" 

[a  for  otlier 

my  friend, 


0^4  and  (si48ali2Na4)Oe4.  Petalite  having  the  vohime  of 
these,  and  its  composition  not  being  then  definitely  set- 
tled, was  referred  to  the  same  general  formula,  while 
orthoclase,  from  its  less  density,  was  conjectured  to  be 
30(M./)2).  As  regards  the  homoeomorphous  triclinic  feld- 
spars, it  was  then  said  that  "  between  anorthite  and  albite 
may  be  placed  vosgite,  labradorite,  andesine,  and  oligo- 
clase,  whost  composition  and  densities  are  such  that  they 
all  enter  into  the  same  general  fornn^la  with  them,  and 
have  the  same  equivalent  volume.  The  results  of  their 
analyses  are  by  no  means  constant,  and  it  is  probable  that 
many,  if  not  all  of  them,  may  be  variable  mixtures  of 
albite  and  anorthite.  Such  crystalline  mixtures  are  very 
common ;  thus  in  the  alums,  aluminium,  iron  and  chrom- 
ium, and  potassium  and  ammonium,  may  replace  one 
another  in  indefinite  proportions.  .  .  .  Heintz  has  shown 
by  fractional  precipitation  that  there  are  mixtures  of 
homologous  fatty  acids,  which  cannot  be  separated  by 
crystallization,  and  have  hitherto  been  regarded  as  dis- 
tinct acids.  The  author  insists  that  the  possibility  of 
such  mixtures  of  related  species  should  be  constantly 
kept  in  view  in  the  study  of  mineral  chemistry.  The 
small  portions  of  lime  and  potash  in  many  albites,  and  of 
soda  in  anorthite,  petalite,  and  orthoclase,  are  to  be 
ascribed  to  mixtures  of  other  feldspar-species." 

§  24.  These  conclusions  were  reiterated,  in  1855,  in  a 
paper  giving  the  results  of  my  chemical  studies  of  these 
feldspars  (when  Scheerer's  hypothesis  was  noticed),  and 
it  was  said  that  similar  views  "  must  also  be  extended  to 
the  scapolites."  *  Some  years  later,  in  1864,  Tschermak  f 
put  forth  a  view  similar  to  that  advocated  by  Von  Wal- 
tershausen  and  myself,  and  maintained  that  the  feldspars 
proper  were  reducible  to  three  species,  adularia  or  ortho- 

*  Examinations  of  Sc  ne  Feldspathic  Rocks;  L.,  E.  &  D.  Philos.  Mag., 
May,  1855. 

t  Tscliennak,  1864,  K.  K.  Academie  Wissenschaft,  Wien,  and  Pogg. 
Ann.,  1865,  v.,  139.  See  also  tlie  author's  Chem.  and  Geol.  Essays, 
p.  444. 


296 


A  NATURAL  SYSTEM   IN  MINERALOGY. 


IVIII. 


li/-: 


clase,  albite,  and  anorthite.  While  recognizing  the  fact 
that  certain  potash-soda  feldspars  (such  as  j)eithite)  are 
made  up  of  alternations  of  orthoclase  and  albite,  he  fur- 
ther concluded,  as  I  had  already  done,  "  that  oligoclase, 
andesine,  and  labradorite  appear  to  be  members  of  a  great 
series,  with  many  transitional  forms,  and  may  be  regarded 
as  isomorphous  mixtures  of  albite  with  anorthite,  some- 
times with  small  admixtures  of  orthoclase." 

§  25.  With  regard  to  this  conception  of  the  nature  of 
these  intermediate  feldspars,  it  should  be  noted  that  the 
chemical  difficulties  in  the  way  of  verifying  it  are  much 
greater  than  in  the  case  of  soluble  compounds,  where,  as 
in  th^  case  of  the  fatty  acids  just  mentioned,  solution  and 
separation  by  fractional  preci^^itation  are  possible,  or 
where  differences  in  volatility  may  be  appealed  to.  While 
a  definite  feldspar-species  having  the  composition  assigned 
to  labradorite  doubtless  exists  in  nature,  it  is  nevertheless 
true  that  a  mixture  of  proportions  of  anorthite  and  albite 
containing  equal  parts  of  alumina  would  give  a,  centesi- 
mal composition  identical  with  that  assigned  to  labra- 
dorite, just  as  the  composition  of  a  fatty  acid  may  be 
simulated  by  a  mixture  of  its  higher  and  lower  homo- 
logues.  In  so  far  as  the  view  of  Von  Waltershausen  and 
myself,  since  adopted  by  Tschermak,  is  true,  the  action  of 
acids  capable  of  attacking  the  basic  feldspars  will  enable 
us  to  discriminate  between  admixtures  and  definite  inter- 
mediate species.  That  the  latter  should  occur  in  nature 
is,  a  priori^  probable  from  the  composition  of  the  parallel 
series  of  the  zeolites,  in  which  appear  well  crystallized 
species,  having  the  atomic  ratios  (excluding  the  water) 
of  the  intermediate  feldspars,  and  also  from  the  evidences 
of  species  like  hyalophane  and  leucite.  The  late  observa- 
tions by  Tschermak  as  to  the  action  of  acids  on  various 
intermediate  scapolites,  to  be  noticed  farther  on  (§  75), 
go  far  to  show  that  these  are  not  admixtures  but  integral 
compounds. 

§  26.   In  concluding  the  paper  of  1854,  which  I  have 


11. 

ict 
ire 
ar- 
ise, 
•eat 
(led 
tme- 

te  of 

b  the 

nuch 

i-e,  as 

I  and 

e,   or 

While 

signed 

;hele8S 
albite 

entesi- 
labra- 

nay  be 
homo- 
en  and 

3tion  of 
enable 
inter- 
nature 
parallel 
staUized 
water) 
vidences 
observa- 
i  various 

1  (I  75), 
integral 


;e 


VIII.] 


A   NATURAL  SYSTEM    IN    MINEIlALOGY. 


297 


here  reviewed,  it  was  said  with  reference  to  the  problem 
of  a  natural  8y.stein  in  mineralogy,  then,  as  now,  before 
the  writer:  — 

"No  mineralogical  classification  can  be  complete  which 
does  not  take  into  account  both  the  chemical  and  the 
l)hy8ical  characters  of  species ;  and  the  connection  be- 
tween these,  which  is  shown  in  the  relation  of  equiva- 
lent weight  to  specific  gravity,  must  constitute  an  iir^^or- 
tant  element  in  a  natural  system.  Guided  by  their  physi- 
cal characters  and  composition,  we  bring  together  such 
homoeomorphous  species  as  belong  to  one  chemical  sub- 
type, and  from  the  densities  fix  their  formulas  ainl  com- 
parative equivalent  weights.  From  the  ct)mparison  of 
the  formulas,  and  the  associations  of  these  different  min- 
erals, we  must  also  decide  which  are  to  be  considered  as 
mixtures  and  which  are  true  species.  Until  we  shall  have 
determined  with  certainty  the  comparative  volumes  of 
dissimilar  crystalline  forms,  the  relations  of  species  differ- 
ing in  this  respect  must  be  decide'^,  by  their  affinities,  and 
their  places  in  a  homologous  series  must  remain  unde- 
termined. In  this  way  we  may  hope  to  arrive  at  a  miner- 
alogical classification  which  shall  satisfy  alike  the  chemist 
and  the  naturalist." 

§  27.  Before  going  farther,  it  seems  proper  to  advert 
to  the  history  of  the  notion  of  polymerism  in  silicates  and 
carbonates,  which  enters  into  the  views  maintained  in  the 
author's  papers  of  1853  and  1854 ;  and  to  show  its  rela- 
tion to  the  views  previously  put  forward  by  Auguste 
Laurent.  He  had  already,  in  1847,  proposed  to  reduce 
all  natuial  silicates  to  a  small  number  of  types,  correspond- 
ing to  the  observed  atomic  ratios.  These  yield  both  neu- 
tral and  basic  salts,  according  to  Laurent,  who,  moreover, 
in  his  notation,  admitted,  in  order  to  explain  the  complex 
results  of  chemical  analysis,  a  divisibility  of  molecules  to 
which  he  assigned  no  limit,  and  supposed  that  protoxyds 
and  sesquioxyds  might,  within  certain  limits,  replace  each 
other  indefinitely.     He  also  extended  a  similar  view  to 


298 


A  NATUUAL  SY8TKM   IN  MINEKALOOY. 


ivm. 


i 


the  bonitos,*  In  a  Hubsticjuent  memoir,  in  1841),  Laurent 
criticised  the  iul)itrary  formulusj  proposed  ly  chemical 
miiiendoyists,  and  showed  that  tlie  rehitions  therein  bet 
forth  were  often  but  ai>proxiinations.  It  was  j)ointed  out 
by  liim  that  in  many  rehited  species,  as  for  exami>le  in  the 
various  micas,  the  atomic  relations  between  sescjuioxyds 
and  ])rot()xyds  were  not  constant,  and  it  was  argued  that 
•tliese  two  chisses  of  bases,  and  water,  were  ca[)able  of 
rephiclng  each  other  mutually,  within  certain  limits,  in 
ratios  which,  as  represented  by  him  in  atomic  formulas, 
seemed  to  be  indelinite.  He  also  insisted  on  the  impor- 
tance in  silicates  of  small  portions  of  water,  which,  though 
generally  neglected  in  the  formulas,  ought  not  to  he 
regarded  as  accidental.  This  later  pai)er,t  however,  while 
rellecting  the  perplexed  state  of  chemical  mineralogy, 
fails  to  propose  any  solution  of  the  difficulties.  The 
reader  will  note  the  broad  distinction  between  the  simple 
formulas,  with  an  indefinite  divisibility  of  molecules, 
adopted  by  Laurent,  and  the  complex  formulas,  necessa- 
rily including  many  atoms  of  base,  employed  by  the  writer, 
further  supplemented  by  the  conception  of  crystalline 
admixtures  of  homceomorphous  species. 

§  28.  It  was  not  until  1860  that  the  doctrines  of  liigh 
equivalents,  and  of  the  existence  of  polycarbonates  and 
polysilicates,  maintained  by  the  writer  in  1852  and  1853, 
found  an  advocate;  when  Ad.  Wurtz  again  put  forth  the 
notion  of  polysilicates,  explaining  their  genesis  from  the 
union  of  several  molecules  of  silicic  hydrate  and  the  suc- 
cessive elimination  of  water.  He  cited  in  this  connection 
the  example  of  the  metastannates  of  Fr(imy,  which  contain 
five  quadrivalent  molecules  of  tin.  Wurtz  did  not,  how- 
ever, attempt  in  any  way  to  discuss  the  difficulties  pre- 
sented by  the  composition  of  the  native  pol^-silicates  (for 

*  Comptcs  Rendus  des  Trav.  de  Chimie,  July,  1S47,  from  Comptes 
Keiidus  de  I'Acad.  xxiii.,  1050,  and  xxiv.,  5)4.  For  an  analysis  of 
Laurent's  memoir  by  the  writer,  see  Amer.  Jour.  Science,  1848,  v.,  405. 

t  Sur  les  Silicates;  Comptes  liendus  des  Trav.  de  Chimie,  1849, 
pp.  250-288. 


VIII.) 


A    NATURAL  HYHTKM    IN    MINICItALOOY. 


299 


certain  of  which  ho  proposed  Btriustiirui  fonuuhis),  or  to 
fix  their  inolecuhir  weights,  uiul  he  seeiiis  to  hiive  over- 
looked the  previous  contributions  to  tlie  subject  by  the 
present  writer.* 

§  2\).  In  1859,  in  n  paper  on  "Euphotide  and  Saussu- 
rite,"  t  the  writer,  luiving  made  an  exteniK'd  ciuMuical  and 
luineralogical  study  ol'  the  typical  saussuritc,  as  found  in 
the  euphotide  of  Monte  Rosa,  in  Switzerland,  showed  that 
it  was  not  a  feldspar,  as  generally  supposed,  but  a  finely 
granular  or  compact  silicate  having  the  hardness  of 
quartz,  a  specific  gravity  of  3.305-3.385,  and  the  composi- 
tion of  a  lime-soda  ej)idote,  or  a  zoisite,  to  which  latter 
species  it  was  referred.  In  this  connection  he  called 
attention  to  the  observation  of  Rammclsberg,  that  zoisite 
is  apparently  identical  in  centesimal  composition  with 
meionite,  the  most  basic  of  the  scapolites,  which  has  a 
hardness  of  6.0,  a  specific  gravity  of  2.6-2.7,  and  is  readily 
decomposed  by  strong  acids.  It  was  further  noticed  that, 
while  boiling  concentrated  sulphuric  acid  did  not  attack 
pulverized  saussurite,  "  it  was,  however,  partially  decom- 
posed by  tliis  acid  after  having  been  strongly  ignited." 
Attention  was  then  called  to  changes  produced  in  the 
denser  silicates  by  heat,  and  it  was  noted  that  epidote, 
according  to  Rammelsberg,  has  its  density  reduced  from 
3.40  to  3.20  b}"-  ignition,  while  saussurite,  accoiding  to  the 
original  observation  of  Saussure  liimself,  is  converted  by 
fusion  into  a  soft  glass  having  a  density  of  2.8.  The 
specific  gravity  of  garnet  was  found  by  Magnus  to  be 
reduced  one  fifth  by  fusion,  and  that  of  idocrase  from  3.34 
to  2.94.|     The  silicates  thus  modified  by  heat  are,  like 

*  Ad.  Wurtz,  Rep.  de  Clilmle,  1800,  ii.,  464;  also  .lour.  Chem.  Soc.  of 
London,  1862,  p.  387;  and  Lemons  de  Philosophic  Chimique,  1864,  p.  ISO. 
See  farther,  on  polysilicates,  Naquet,  Principcs  de  Chimie,  1867,  i.,  175. 

t  Contributions  to  the  History  of  2uphotide  and  Saussurite,  Amer. 
.Jour.  Science,  ia">(),  xxvii.,  .3:l6-a4!). 

t  The  observations  of  Greville  Williams  on  beryl  show  that  this  min- 
eral, having  a  density  of  2.65-2.01),  when  fused  before  the  oxyhydrogen 
blowpipe,  gives  a  clear  glass,  which  may  be  scratched  by  quartz,  and  has 
a  density  of  2.40-2.42.    The  fusion  of  quartz  gives  in  like  manner  a  glass 


-ill 
hi 


\\ 


it,' 


300 


A  NATURAL  SYSTEM  IN   MINERALOGY. 


[VIII. 


f^HfJtf  11 


i| 


meionite  and  nephelite,  decomposable  by  acids,  and  all 
these  facts  were  adduced  as  evidences  that  the  action  of 
heat  is  to  reduce  such  complex  silicates  to  simpler  and 
less  dense  forms. 

§  30.  In  conclusion  it  was  said  that  "  the  two  silicates 
zoisite  and  meionite  offer  a  remarkable  example  of  that 
isomerism  in  mineral  species  upon  whose  importance  I 
have  long  insisted.  The  relation  of  the  specific  gravity 
to  the  empirical  equivalent  weights  of  minerals  must  enter 
as  an  essential  element  into  a  classification  which  shall 
unite  the  chemical  and  natural-historical  systems.  Simi- 
lar isomeric  relations  exist  between  cyanite  and  sillimanite 
(fibrolite),  rutile  and  anatase,  and,  as  I  have  elsewhere 
endeavored  to  show,  among  the  carbon-spars.  It  becomes 
necessary  in  the  study  of  mineral  species  to  determine 
their  relative  equivalent  weights,  to  which  specific  gravity 
must  be  the  chief  guide." 

§  31.  The  relations  of  the  members  of  the  scapolite 
group  *  as  a  series  parallel  to  the  feldspars,  already 
pointed  out  by  the  author  in  1855,  were  not  lost  sight  of, 
nor  their  connection  with  saussurite,  but  were  the  subject 
of  a  communication  to  the  French  Academy  of  Sciences, 
in  1863,  which  was  translated  by  the  author  and  published 
at  the  time,  in  the  American  Journal  of  Science,  as  already 

to  which  a  density  of  2.22  has  been  assigned.  Williams,  in  repeating  the 
experiment  with  rock-crystal,  of  density  2.65,  obtained  before  the  oxyhy- 
drogen  blowpipe  fused  globules,  which  in  five  experiments  gave  a  specific 
gravity  of  2.17-2.21.  He  noted,  moreover,  that  alumina  thus  fused,  as  in 
the  experiments  of  Gaudin,  becomes  crystalline  on  cooling,  and  has  a 
density  of  only  3.45;  that  of  corundum  being  about  4.00.  The  crystals  of 
alumina  got  by  the  method  of  Fremy  and  Feil,  which  consists  in  decom- 
posing an  aluminate  of  lead  by  fusion  in  contact  with  silica,  have,  how- 
ever, all  the  characteristics  of  corundum,  and  a  density  of  3.9-4.1  (Gre- 
ville  Williams,  Proc.  Roy.  Soc.  London,  1873,  p.  409,  and  also  Fouqu^ 
and  Michel  L^vy,  Synthase  des  Mineraux,  etc.,  p.  222). 

*  The  scapolites  have  very  lately  been  taken  up  and  discussed  from 
the  author's  point  of  view  by  Tschermak,  Monatshefte  der  Chemie, 
December,  1883,  as  will  be  noticed  farther  on.  The  slight  change  in  the 
empirical  formula  of  meionite  suggested  by '  schermak  does  not  atfect  the 
present  argument. 


VIII.] 


A   NATCJIIAL  SYSTEM   IN  MINERALOGY. 


301 


ng  the 
oxyhy- 
jpecific 
as  in 

has  a 
stals  of 
decom- 
e,  how- 

1  (Gre- 
Fouque 

.d  from 

hemie, 

e  in  the 

ffectthe 


noticed  in  §  10.*  In  this  paper,  after  recalling  the  general 
argument  so  often  set  forth  as  to  the  principles  of  a  new 
system  of  mineralogical  classification,  it  was  said,  "  Meio- 
nite,  with  the  oxygen-ratios  3  :  2  : 1,  is  the  most  basic  term 
known  of  the  series  of  the  wernerites  (scapolites).  The 
proportion  of  silica  in  these  minerals  augments  until  we 
reach  in  dipyre  the  ratios  6:2:1,  with  a  density  which 
does  not  exceed  2.66.  We  might  then  expect  to  find  a 
silicate  which  should  be  to  dipyre  what  zoisite  or  saussu- 
rite  is  to  meionite,  and  Mr.  Damour  has  recently  had  the 
good  fortune  to  meet  with  such  a  mineral  in  a  specimen 
of  jade  from  China,  of  which  he  has  given  us  the  descrip- 
tion and  the  analysis.  (Comptes  llendus,  May  4,  1863.) 
This  substance  closely  resembles  in  its  physical  and  chem- 
ical characters  the  saussurite  or  jade  from  Monte  Rosa,  of 
which  it  has  the  density,  3.34.  It  is  a  silicate  of  alumina, 
lime,  and  soda,  and  gives  the  same  empirical  formula  as 
dipyre.  We  may  expect  to  find  between  saussurite  and 
this  new  species,  to  which  Damour  gives  the  name  of 
jadeite,  other  jades,  having  formulas  which  will  correspond 
with  the  wernerites  intermediate  between  meionite  and 
dipyre.  ...  By  its  hardness,  its  specific  gravity,  and  its 
indifference  to  acids,  jadeite  is  completely  separated  from 
the  wernerite  group,  and  takes  its  place  alongside  of 
zoisite  or  saussurite,  with  the  garnets,  idocrase,  and  epi- 
dotes." 

§  32.  To  this  last  succeeded  the  paper  of  1867,  on 
"The  Objects  and  Methods  of  Mineralogy,"  already 
noticed  (§§  12-14),  in  which  was  given  a  review  of  the 
subject  as  discussed  by  me  in  various  publications  from 
1853  up  to  that  date.  Before  proceeding  to  show  the 
systematic  application  of  the  principles  already  set  forth, 
it  is  now  proposed  to  consider  farther  the  question  of  the 
relation  between  the  atomic  weights  and  densities,  so 
often  insisted  upon  in  the  above  publications.     The  study 

*  Compte  Rendu  de  I'Acad.,  June  29,  1863,  and  Amer.  Jour.  Science, 
,  1863,  xxxvi.,  426-428;  also  the  author's  Chem.  and  Geol.  Essays,  p.  .446. 


ff'i  ■-[ 


:^5|,| 


302 


A   NATURAL   SYSTEM   IN   MINERALOGY. 


[VTII. 


of  the  so-called  equivalent  or  atomic  volumes  of  solid  and 
liquid  species,  got  by  dividing  the  assumed  equivalent 
weight  of  these  by  their  specific  gravities, —  water  being 
taken  as  unity, —  has  occupied  the  attention  of  many 
chemists  since  the  early  investigation  of  the  subject  by 
Le  Royer  and  Dumas.  The  application  of  this  method  to 
hydrocarbonaceous  bodies,  or  to  hydrated  or  double  salts 
of  admitted  high  equivalent,  is  comparatively  simple,  but 
it  becomes  more  difficult  when,  wo  have  to  deal  with  such 
compounds  as  mineral  silicates,  for  which,  as  in  the  case 
of  feldspars,  micas,  epidotes,  and  tourmalines,  the  ingen- 
uity of  mineralogical  chemists  has  devised  chemical 
formulas  often  exceedingly  complex  and  difficultly  com- 
mensurable. For  all  such  cases  I  have  shown  that  the 
atomic  formulas  already  described  furnish  a  simple  solu- 
tion. 

§  33.  In  the  atomic  notation  adopted  by  me  since  1853, 
the  ordinary  cliemical  symbols  of  the  elements  are  em- 
ployed to  represent  one  part  by  weight  of  hydrogen,  or 
eight  parts  by  Aveight  of  oxygen,  and  the  proportions  of 
other  elements  which  unite  with  these  respectively.  In 
other  words,  the  coefficients  of  the  symbols  of  the  elements 
in  the  ordinary  notation  are  multiplied  by  the  atomicities 
of  the  respective  elements,  for  the  atomic  notation.  The 
symbols  in  the  latter  are  distinguished  from  those  repre- 
senting molecular  weights  by  the  use  of  small  letters,  and, 
to  |)revent  the  confusion  which  might  otherwise  arise  from 
the  abseiice  of  capital  letters  in  the  formulas,  a  coefficient 
is  in  all  cases  employed  after  the  symbol  of  the  element ; 
while  in  constructing  condensed  formulas  the  values  of 
"m"  may  be  represented  by  fractions.  Thus,  the  general 
formula  of  pyroxene  in  the  atomic  notation  being  w(si2mi03), 
if  the  value  of  n  be  30,  and  m  =(ca6mg^fe6),  the  proper 
atomic  formula  of  pyroxene  will  be  si6o(cai5mgiofe5)o9o. 

§  34.  But,  as  we  have  elsewhere  shown  (§  21),  the 
variable  relations  between  silica,  alumina,  and  protoxyds, 
in  closely  related  species ;  the  intervention  of  boron  and 


VIII.] 


A  NATURAL   SYSTEM  IN  MINERALOGY. 


808 


II. 

nd 

ng 
my 

by 
I  to 
alts 
but 
iucb 
case 
igen- 
iiical 
com- 
,t  tbe 
solu- 


titanium,  on  the  one  hand,  and  of  sulphur,  fluorine,  and 
chlormc,  on  the  other,  permit  a  farther  generalization,  by 
which  silicates  are  affiliated  to  quartz,  on  the  one  hand, 
and  to  corundum  and  spinels,  on  the  other.  We  thus 
arrive  at  a  general  atomic  formula  n(A-}-E),  in  which  A 
represents  an  atom  of  silicon,  boron,  or  titanium,  or  of 
hydrogen  or  any  metal,  and  E,  an  atom  of  oxygen  or  sul- 
phur, or  of  fluorine,  chlorine,  or  oxysulphion.  Dividing 
now  the  molecular  weight  of  the  compound  bj-  w,  we  get 
the  value  of  A+E,  which  is  the  mean  weight  of  the  indi- 
vidual or  atomic  unit  of  the  species,  whether  this  be  oxyd, 
silicate,  oxyfluorid,  oxychlorid,  or  oxysulphid.  It  is  this 
weight,  designated  a;-;  P,  which  for  each  such  species  must 
be  the  term  of  comparison  in  fixing  the  atomic  condensa- 
tion of  the  spec'cs.  The  mean  unit-weight  thus  deduced, 
divided  by  the  specific  gravity  of  the  species,  Avater  being 
unity,  gives  the  v^dume,  V,  of  the  atomic  unit.  In  sili- 
cates, the  value  of  P  is  deduced  by  dividing  that  of  the 
empirical  atomic  formula  by  the  whole  number  of  oxygen 
atoms,  to  which,  in  the  case  of  oxyfluorids,  oxychlorids, 
or  oxysulphids,  the  number  of  atoms  of  fluorine,  chlorine, 
or  sulphur  is  to  be  added.  In  this  way  only  is  it  possible 
to  obtain  direct  comparisons  of  volume  between  different 
mineral  species,  as  was  indicated  in  1852,  and  will  be  fully 
shown  in  the  third  part  of  this  paper.* 

§  35.  The  principles  hitherto  maintained  by  the  author 
as  the  basis  of  a  natural  system  in  mineralogy,  may  be 
resumed  as  follows :  — 

1.   The    conception   of  high    equivalent    or   molecular 

*  Dana,  in  his  inquiry  into  the  subject  of  atomic  volumes  in  1850 
(Amer.  Jour.  Science,  ix.,  221),  proposed  to  divide  tlie  volumes  tieduced 
from  the  empirical  chemical  formulas  by  the  number  of  atoms  of  ele- 
ments in  these  formulas.  Thus  (0=8),  SiOa,  AljOi,  and  CaO,  were,  in 
the  notation  adopted  by  him,  supposed  to  contain  respectively  four,  five, 
and  two  elemental  atoms,  whereas  in  atonuc  notation  they  evidently 
correspond  to  thre;-,  three  and  one  oxyd-units.  Ilenc(>,  as  I  long  since 
showed,  the  results  obtained  by  such  a  discussion  of  atonuc  vohunes  were 
fallacious.     (Amer.  .lour.  Science,  1853,  xvi.,  214.) 


'■'i,: 


304 


A  NATURAL   SYSTEM    IN    MINERALOGY. 


[VIII. 


'nil 


weights  like  those  of  the  carbon  series  in  so-called  organic 
chemistry,  extended  to  all  mineral  compounds;  as  was 
especially  maintained  for  th^  carbon-spars,  the  spinels,  and 
tl'o  various  natural  silicates,  and  illustrated  by  the  hypo- 
thesis of  polysilicates  and  polycarbonates,  with  many  atoms 
of  base. 

2.  The  conception  that  the  laws  of  progressive  or  ho- 
mologous series,  previously  recognized  only  in  hydrocar- 
bonaceous  bodies,  must  be  extended  to  mineral  species, 
and  are  of  universal  application. 

3.  The  conception  that  the  variations  observed  in  the 
chemical  composition  of  such  mineral  species  are  due,  not 
only  to  their  highly  poly  basic  character,  but  also,  in  cer- 
tain cases,  to  indefinite  admixtures  of  homoeomorphous 
species,  as  pre  piously  indicated  by  Delesse,  Scheerer,  and 
Von  Waltershausen,  extended  and  generalized  by  myself, 
and  subsequently  adopted  by  Tschermak. 

4.  The  attempt  to  fix  the  molecular  weights  of  such 
compounds  as  the  polysilicates  and  polycarbonates  from 
their  densities  as  compared  with  those  of  species  the  mini- 
mum molecular  weights  of  which  are  otherwise  determined ; 
and  the  assumption  that  for  homoeomorphous  solids,  and 
probably  for  all  solids,  tlie  molecular  volumes  are  identical. 

5.  The  adoption  of  atomic  formulas  to  represent  the 
•composition  of  mineral  species,  and  the  showing  that  com- 
parisons of  the  volumes  or  spatial  relations  of  complex 
species,  like  the  silicates,  should  be  based  on  the  numbers 
which  are  deduced  from  these  atomic  formulas,  and  which 
lapresent  the  relative  volumes  of  the  unit-weight  in  the 
species  compared.  P  being  the  unit-weight  got  by  divid- 
ing the  empirical  molecular  weight  by  the  number  of  oxyd- 
atoms  in  the  formula  (including  any  chlorid,  fluorid,  or 
sulphid  atoms  which  may  be  present),  and  D  the  specific 
gravity,  the  volume  of  the  unit,  designated  as  V,  is  repre- 
sented by  the  quotient  obtained  by  dividing  P  by  D. 

6.  The  showing  that,  in  related  and  homologous  species, 
the  hardness  and  chemical  indifference  are  inversely  as  the 


VUI.] 


A  CLASSmcATIOK  OF  SILICATES. 


One 

value  of  V:  or  in  ni-u 

the  co„de„sati„;,  tkTrZZ7^'  "'"'  f'^  "'"'^"^o  "ith 

?36     rn''^""   "'"''"™^™'^  ™'  ™'CATES 

oWfi,,„„„  „,  „  ■»  J;h    -eo„d  part  of  this  papL.  to  "t'C 
Silicates,  for  the  reason  tLt    '',  I    J'  ''^°"'"  *''e  Natural 
<="..T.lex  a„d  the  la.^es"': /''^^ '"«-''  "''^  ">"«' 
P'ysical  and  their  chemieal^v?  ''^ ""*■>'<'  species,  their 
t'oiong,,,,  studied  tClor:?:*^ .T"  ''»^°  ■»°- 
this  It  may  be  added  that  the  t  f     7  "**''  S™"P-    To 
employed  a  olassifloat  on  blsedl  H  '"'  '°^  """'/vears, 
""".gement  of  his  own  pr  vate  e  7!-''""""'"''^  ^"^  *he 
»"'oates.      These  „,ay  be  re^J^d       '°"  "'  '^'  """^ 
great  natural  order  and  t-If*'    ^''  "^  '^onstitutinj;  one 
i'"Po.;ta„ee  of  coSdert TrLr'",  '"^^'■■«"="  *°  "- 
chenueal  and  tl,e  physical  hil?        f  ™'  '>''*em  alike  the 
that  a  fundamental  SuonZr  T''''' "  """^  "^^  ^-^ 
hy  their  chemical  eons  t"Hn  •°^"'  '^  """  Presented 

o^yl  or  sesqnioxvd°d    o^'h^i""'"*'-^  <='*-'  P™t- 
«aso„theorlrSmca^1s^^L^^''"''^''•    ^""^  ^hieh 

P™t„siHcate,Protope:S"1rd^:!^'''7  ™ 

The  names  of  protow.!  7  J         ^eradicate, 
pounds,  and  of  peCyd^i'lP-'^lt  for  ferrous  com-    ' 

a"d  sesquisalt,  for  fe,i.io  com„  '       '     ""^^  »f  sesquioxyd 
■sfs:  and  when,  in  naminrr      K"'"'f'^""""'"- *»  <=hem- 
hecame  necessaiV  to  sele  fa  er™".  T''^^  "^  ^'"^"tes,  it 
impounds,  aluminic  comlu  1    'Vr®"""'  "'^^  ferric 
»"d  aluminie  ^esqnioxyZ  partMv       7""'  ''"^''  fe™" 
sutured  to  substitute  for  sesoS   ?     "  '"'^  °'^'"'  I 
"■hoate  the  shorter  and  mornun)^'-"  "'"^  P^tosesqui- 
^f  e  and  Protopersilicate     With  r"""  "'""'  "^  P^'i"- 
''h.oh  also  include  chrome  and  1''"'"°''^''  hases, 
'-.rco„i«,  since,  uotwithstond'nt?h   *'"";  "^''^'  '^  '™ged 

^"""■""-■'-■^■-■-^""^atsraSr::,:^^^^^^ 


306 


A   NATUllAL   SYSTEM    IN    MINERALOGY. 


[VIIX. 


( i    i;; 


place  it  at  ihe  side  of  alumina.  Here  also  bismuthic  oxyd 
probably  belongs.  Boric,  titanic,  niobic,  and  tantalic 
oxyds,  all  of  which  are  found  in  silicates,  are  ranged,  as 
already  stated,  with  silica,  which  they  are  regarded  as 
replacing. 

§  37.  Inasmuch  as  zirconia  and  chromic  and  manganic 
oxyds  are  but  exceptionally  present  in  silicates,  and  ferric 
oxyd,  though  more  commonly  found  than  they,  is  much 
less  frequent  therein  than  the  alumina  which  it  sometimes 
replaces,  it  may  be  said  that  it  is  essentially  the  relations 
of  alumina  to  the  protoxyds  and  to  silica  which  we  are 
now  called  to  consider.  Native  silicates  may  be  divided 
into  those  with  and  those  without  alumina,  the  latter  di- 
vision constituting  the  first  sub-order  —  Protosilicate. 
Again,  the  aluminiferous  silicates  either  contain  combined 
protoxyds,  constituting  the  second  suu-order  —  Protoper- 
aillcate  ;  or  are  without  protoxyds,  making  the  third  sub- 
order—  Persilicate.  The  presence  or  absence  of  combined 
water,  —  it  being  an  element  widely  diffused  in  nature,  — 
is  of  subordinate  importance  in  the  study  of  the  silicates. 
Upon  the  general  distribution  of  silica  and  alumina  in  the 
crust  of  the  earth,  and  the  relations  of  these  to  each  other, 
to  protoxyd-bases,  and  to  igneous  and  aqueous  solvents, 
is  based  the  whole  genetic  history  not  only  of  the  three 
sub-orders  of  silicates,  but  of  quartz,  and  the  non-silicated 
oxyds. 

The  .affinities  which  determine  the  nearly  contempora- 
neous formation  of  protosilicates  and  of  protopersilicates 
are  displayed  in  many  different  and  unlike  conditions, 
which  merit  especial  consideration.  This  distil  ction  is 
well  seen  in  the  basic  crystalline  rocks,  wherein  pyroxene 
and  chrysolite,  often  with  magnetite,  are  found  side  by 
side  with  feldspars.  Whether  this  separation,  which  may 
be  supposed  to  have  taken  place  in  a  plutonic  magma,  was 
effected  with  or  without  the  intervention  of  water,  is  im- 
material to  our  present  inquiry,  since  we  know  that  the 
chemical  affinities  involved  lead  to  similar  results  alike  iu 


\* 


vm.] 


A   CI,ASSmcAT,ON  OP  SIUCATKS. 


»;.ecessively,  chrysolite"  mateUe^^'''"^  basic  ,„ag,„a, 
That  3m.ilar  affiniUes  eonS'l^^™''""'  "'"'  '"'^ar 
f  :  '^™'^<'  temperatures  s  sW^'^^  "i  ''™'''"=^  "^  ^v^ter 
cret,o„ary  granitoid  veins  wW    \^  ""'^^^^  '«  "on- 
»d  pyroxene  are  fo„„d  ~ilT    1'?"'''  '"''P''i'>ole, 
•te,  ,„icas,  garnet,  and  epidote  of     '""j '!,'*pai.,  scapo- 
tlie  one  hand,  and  with  n  amet,/       •'""'  '''^  'J'"«'t2.  on 
on  the  other.  "'aguetUe,  spinel,  and  oorundLm" 

P™topm-siHoaTst''prt!nTed''r'l"   °'  P™'o«ilicates  and 

"■^t-  .  In  the  veins  rdgeodst  T"''""'  *"■»  ^^^ 
seen,  side  by  side    fhl    ^  ?         "'""<'  '"  such  rock,  »,.„ 

"atolite,  a„dV:';h„  :  ^d'th  "'"'  P-'^^e.  otnite 
sented  by  prehnite,'^>pid;te  and  thr"*"?'™"""''^  'W 
"■ore  rarely  by  orthoclase  and  lu  7"""'  '"'^'''^  and 
™aime,-b„th  quartz  andtt^e  ^  V'?"™'  ""<•  *°- 
The  same  distinction   is  owf.  ''""«^  "'«<>  P™en' 

forming  in  the  channels  of  .."'  .'"  ""^  P'oducts  now 
P!-tolitic  and  ^eoliti  1  lilte"  Ir  *''"™'"  "^""^^  wherl 
^'fferentiation  less  marked  wL'     "'^•'"'f '^d.    Nor  is  the 
Da»br«e,  water  at  a  high  teml  '."^  '"  "'"  «'^Perin,ents  of 
P''otosilicate  allied  to  Xnitl?  If "!  ""'^  "P°«  g'«««-    A 
PKoxene  and  quartz,  fte  X  f/"  '"""'"''  '»ge?her  with 
^'l'°a,  with  a  portion  of  »,„'""■'  '°'»««n  ^etainin^ 
i'eated  solutions,  holdinJ  oh'"'-      ^"'"'  ^™ilar  super 
*-»encs,  crystal's  of  t  fo Se  0?^"°""  "^  '"-^ X 

8   39     Tn  fV. 

'^  known  that  thc^ula  ^1  r"^  ""'f  *™"«f<'™atirs     ft 

"■»  --  of  atmos'pht::\ttreCir*-^-«'' 

-  ^"^^^«  *^ieir  complete 


308 


A  NATURAL  SYSTEM   I^    MINERALOGY. 


[VIII. 


decomposition.  The  lime  and  magnesia  of  amphibole, 
pyroxene,  and  chrysolite,  are  thereby  dissolved,  together 
with  a  large  proportion  of  the  silica  itself;  a  part  of  this, 
however,  according  to  Ebelmen,  remains  behind,  together 
with  the  iron,  changed  from  a  ferrous  condition  to  that  of 
ferric  hydrate.  In  the  sub-aerial  decay  of  such  protoper- 
silicates  as  the  feldspars  and  closely  related  species,  the 
protoxyd-bases,  chiefly  alkalies  and  lime,  pass  into  solu- 
tion, together  with  a  large  part  of  the  silica ;  and  the 
alumina,  united  with  the  remainder  of  the  silica,  and  with 
a  portion  of  water,  remains  as  an  insoluble  compound, 
which  in  many  cases  has  the  composition  of  kaolin.  This 
decay  of  the  feldspars  plays  an  important  part  in  terres- 
trial chemistry.  The  process  is  slow  and  gradual,  and  the 
feldspar  softens  and  becomes  disintegrated  before  the  loss 
of  protoxyds  is  complete,  so  that  the  clays  thus  formed 
still  retain,  in  many  cases,  a  portion  of  alkali,  which  may 
amount  to  two  or  three  hundredths  (a?i^e,  page  254).  The 
decomposition  of  the  more  basic  feldspars  and  feldspathic 
minerals  will  be  considered  farther  on,  as  also  the  genesis 
of  various  micaceous  and  colloid  or  clr.y-like  persilicates. 

§  40.  From  the  subsequent  transformation  of  clays 
more  or  less  completely  deprived  of  alkalies,  are  appar- 
ently derived,  in  many  cases  at  least,  muscovitic  micas 
and  tourmaline,  together  with  the  crystalline  persilicates, 
kaolinite,  pyrophyllite,  andalusite,  cyanite,  fibrolite,  and 
related  species.  The  micas  just  mentioned  are  more 
stable  under  atmospheric  influences  than  the  feldspars, 
while  those  which,  like  phlogopito  and  biotite,  abound-  in 
protoxyds,  yield  readily  to  decay.  The  harder  and  gem- 
like protopersilicates  resist  to  a  greater  extent  this  pro- 
cess, and  the  more  common  species  of  these  —  garnet, 
epidote,  and  tourmaline  —  are  found  unchanged  in  sands, 
together  with  persilicates,  such  as  andalusite,  topaz,  and 
zircon,  and  with  quartz,  corundum,  spinel,  and  menaccanite. 

Thus  the  natural  processes  of  sub-aerial  decay  destroy 
the  protosilicates,  and  transform  the  predominant  types  of 


VJII.j 


A  CLASarriCAl..^   OB-   slLrOATES. 


309 
protopersilicates  either  inf^ 
more  stable  ty,.:'*/  ,''::;:,  '■"'i'^  "'"■'""'-  nnd 
oate»,  m  all  cases  with  the  stm,.,,  f '  '"'  """  l'««"i- 

protosilicates,  that  is  to  savT  x""'  "^  "'"  "^"'"^"^o  of 
W  these,  v.l,ile  iron  I  lilt''"  "'"'  ''■'""-y'l-bases 
,         »tote,  the  alkalies  ami  li„  e  "  'f/ , '"  ;,'"  """'"We  ferric 
protoslioates,  pass  i,.,„    he    „I  litio'     1  '""S"'^'"  '^  ">« 
s.I,ea  hei.^  liberated  in  a  so,„h  :'!'  ^  "'  ""■'"'""'-■  "- 

-ereted  i„  basic  rrcks,  IjZ":'    -"--  -cl    those 
I>rocess  of  solution  of  s  licatL  „  ""'"'  ^'■l'to™nea„ 

conditions  as  yet  in.ne  f^!  .T'"'"'"''' ^oes  on  under 
•■■"  er  the  inmrence  oHlS  S.r'"'"'  """^  '^''"•'ly 
•;atters  thus  dissolved  co^e  not  ont'?,  "'"""''*•    J"™"  "'e 
''ei>os.ted  in  the  forms  of  zeo  14!,°^ .   !■  f  "'"l^^'ioates 
garnets,  and  tourmalines,  but  a  so  tl      °\  '''''^"■■"•^'  '«'<"'^' 
protos,lieates  which  take  the  fo"f  ""'''"=  »'"'  »"«'ine 
okemte,apoi,hyl,ite,and  wollalle    'f 'f  *'  ™"-"«te, 
solutions,  coming  in  content  ^""^  Protosilicate 

dioxyd,  would  bf  decompred  w^i  "'"""P!'"'''  """""'io 
»tes,  but  with  dissolved  ZlZ-      "T"'"""  <"'  »•■"*"»- 
;!ouble  exchange  silic^ts^slc,   as'sf'^r''''  ^'^"'  by 
fne,  enstatite,  chrysolite  am  7h       ^^P'^''^'  We,  serpen- 
and  pyroxenes.    It  wi    C    menXrrlf  ^"^  "'"P'"'^"'- 
s.l.cates  may,  like  the  felds  Z  b/f         ."'  ''"''  P™'"" 
0..S  and  by  igneous  processeTand  th  fT' '"'''''  ""^  "'l''^- 
■■>»  to  origin  must  be  drawn  betwltt  "  '"'""'  <"«'in<=tio.. 
cates,  of  both  8ubK,rdeTwhic,rr    ]  "'"  »■' Vdrous  sili- 
S'tion,  and  are   oftl?  "  ''""'  '"  "q^oous  de--,- 

q»rt.,  and  the  sa,  e  sprcir'";:' J"""'  -'-'«  "■"•  with 
"'cks,  and  may  be  thfrl  Z'f  ^'^  *""'"'  ''»  P'ftonic 
-'oling  igneous  n,  ss  Cone  tT'""""'""  *™"  " 
reactions  with  magnesian  saft?  "u  '""''""°''''  ^y  "''^ 
S've  rise  to  eompomX  i"  '  T^'  ^  ''°""''  ««^<=hange, 
and  the  chlorites"  whi  e  th r.'  '''.*'''  "■■'^"^*'"'>  »*»« 
Wy  to  be  sough    TZ  relr'^t  "^  »'''™'""'<' '«  Proba^ 


'Iff 


hh 


M. 


'r'i 


!l.. 


I  ' 


310 


^  ^ATUBAL  SYSTEM  IN   MINEUALOOY. 


[VIII. 


U  giving  ovigiu  to  the  l^^fji'^^.e  latter,  by  »ub-ae.>al 

oates,  it  is  the  ^"^Z^^,.^  «-  Fot^yi""--' 
aquenus  action,  wluUi,  uj 

generates  the  V^'-f"'f'-.„„^  between  the  sub-orders 
^  «  42.  While  the  d"""  "*  °™  ^,,1,  genetic  history  a  e 
wllh  have  been  ^/^rj,*'  "  a  t  holevev,  remarkable 
generally  well  -l^fi''^'^'  ^^'..ect  the  protosilieates  with 
Ixanrples  which  serve  *»  «°^^^"^^  ^  i^  species  of  am- 
the  protopersilieates.  ^''"^'tosiUoates,  there  have 
phibole  and  pyroxene,  wh.ch  a  e  V  ,„  j,  „hich,  while 

hitherto  been  »«''«l^'l  "^''^^^  ;„  'external  characters, 
apparently  identica    «''h  ^f^^^;,.,.    Taking  as  a  type  of 
contain  notable  P0'-«^»«  °   f  ,"„e-magnesia  pargas.te,  we 
the  aluminons  a^P'''^"'''';  „*J"  yds,  alumina,  and  silica, 
td  for  the  atomic  '»'-  " ^mdle,  silica  42.2.    This, 
2  : 1 :  S,  which  >^«f«^\Sw,  as  has  been  suggested, 
it  the  alumina  ^^P^^f  ^^^Xwe  tbe  ordinary  amphibole 
a  portion  of  the  silica,  ^™"W  S'v  .„topers.l.ea  e, 

ratio  of  2  :  4.  It  is,  l^^^f  f '  „,,ilite;  while  the  alu- 
having  the  same  f  °""^,  *'\: ^the  analysis  of  Liver- 
„i„ous  species,  S^<^:'"°f^'''fl^i  gastaldite,  a  still  more 
ridge,  gives  the  ratios  3  ^  2  j^8,  a_^  J  ^^^^^^^^  „a,,,ed  by 
aluminous  species,  \-f-^-  ^  ical  characters  have 
species  like  these,  which  from    p  y  writing  man- 

b'een  compared  with  amphAole  ^^^  .,^  ^j^,,,  . 

„er  the  importance  of  «^«™"^^';°„    „gasite  iu  its  ato™'" 
ogy.     Analuminousa.igit«=ueartop    g  213). 

"fations  has  also  been  examined  by^Fo"q^  J^  ^^  ^^^    ^^^ 
From  gastaldite  in  "'^1*  the  ato  ^    ,^  ^^^  ^^^. 

and  alumina  are  1 :  2,  '» J  '"""P^hich  the  ratio  becomes, 

gasite  1  :  i.  we  h"^,  "  f   '  d   o  o"  ">  *'=  ''^^  '^""T"' 
lin  humboldtilite,!  :  iV^d^o  °         ^^^^^^^  ^  .  ^  „, 


[I. 


VIM.] 


A  CLASSIFICATION    OF   SILICATES. 


311 


,te 

iW, 

Ate 
jili- 

ises, 

:der9 
y  are 
kable 
with 

i  ixm- 
ebave 
,  w\iUe 
cacters, 
type  of 
site,  we 
Ld  silica, 
».    ThiSi 
[ggested, 
npWbole 
•vsUicate, 
B  the  aUi- 

oi  Liver- 

stiU  more 

ffered  by 

•ters  bave 

^^  minerai- 
its  atomic 

If  protoxya 
k  and  par- 
^o  becomes, 
aluminous 

,s  1  ••  1^'  "' 
aese  species 


to  the  protosilicates.  In  like  manner,  towards  the  otlier 
limit  of  tiie  prot()i)ursilicates,  we  tiiul  this  ratio  changing 
from  1  :  6  to  1  :  9  ayd  1  :  12,  in  iiulieolite,  rubellite,  and 
the  muscovitic  micas ;  thus  marking  the  transition  to  gem- 
like  persilicates  like  andalusite  and  topaz,  and  to  persili- 
cate  micas  like  kaolinite  and  pyrophyllite. 

§  43.  We  may  conceive  the  relation  of  the  three  snb- 
orders  to  each  other  to  be  represented  by  a  design  of  two 
bands  of  equal  breadth,  but  of  unlike  color,  and  of  dimin- 
ishing intensity  of  color,  protracted  in  opposite  directions 
alowg  a  common  course,  for  a  considerable  part  of  which 
the  two  bands  overlie  or  rather  blend  with  each  other. 
The  unmingled  iJortions  of  these  two  color-bands  repre- 
sent the  protosilicates  and  the  persilicates.  As  a  result  of 
such  an  arrangement,  the  protopersilicates,  towards  the 
protosilicate-end  of  the  continuous  series,  include  com- 
paratively little  alumina,  as  in  melilite,  pargasite,  and 
phlogopite,  while  towards  the  persilicate-end  they  hold  but 
little  protoxyd,  as  seen  in  indicolite,  rubellite,  the  musco- 
vites,  and  pinite. 

§  44.  It  follows  from  what  has  been  already  set  forth 
that  the  more  or  less  arbitrary  ratios  generally  assigned 
by  chemists  to  various  silicates,  and  deduced  from  empiri- 
cal formulas  which  in  many  cases  represent  but  approxi- 
mately the  results  of  chemical  analysis,  are  not  always  to 
be  regarded  as  exact.  Thus,  in  examining  the  various  for- 
mulas hitherto  devised  for  protosilicates,  we  find  that  for 
the  whole  succession  from  chondrodite  to  apophyllite,  the 
atomic  proportions  between  the  bases  and  the  silica  may 
be  represented  by  some  twelve  simple  ratios  between  4 :  3 
and  1:7.  It  is  probable,  in  view  of  the  complex  constitu- 
tion, involving  from  twenty  to  thirty  atoms  of  base,  which 
we  have  assigned  to  these  polysilicates,  that,  while  some 
of  these  ratios  are  exact,  others  represent  but  approxima- 
tions to  the  truth.  The  same  remark  applies  with  equal 
force  to  the  persilicates,  where  a  like  number  of  similar 
ratios  is  made  to  include  all  of  the  known  species.    In  ,he 


;^ 


812  ^  NATURAL  RVai^.i 

,    1       .f  thpir  composition,  how- 

'ever,  U,e  "-''^"V  "-l-'^'';2;;:v'"^  tor  th.  t.l.u.a. 
silica  are  .eta.nca    m  ,,i,i„,tV  gWen  farther  on 

views  ot  i,roto».l.«. U«  •  "U  1  <^  sui,-order»  we  note 

«  45.   In  tl.o  study  "f  >>»'''  ecies  which 

„„f„y  n,iuevalogical  -»en.b       -     ',^.  ,.,,.,.  ,,,„,„v,,ances 
.litfer  widely  in  '*"»  "  'f  ^  „„  ,ve  exau.ine  the  lavgev 
become  »tiU  move  -M'!""""' ,    .  ^  protoneraiUoates.     Here, 
'„d  more  complex  B;-"')  .  "J,  ('1,^ .eolites,  the  feldspars, 
£„r  example,  in  the  ''"'    "^^       ^^^^    similar  and  hom-BO- 
„,d  the  "capolites,  we    nd  l,hj^      J  ,  „Uo  o£  prot. 

„orphou»  species  "^ ^^^^  ,„i„uie.    The  same  tlnng 
oxydsa«dalununa,thes.Uca  s  ^^,^  ,„,,.ovder;  as 

may  be  observed  among  the  n  .^  ^,^  „,„.g„. 

X  eorundophibte  -  -"f '^e   latter  also  present 
ite  with  certain  ■»«,»™;f;.^;  .opposition,  for  in  ditferen 
another  type  ot  variations  m  eo    P        ^^  ,„,^„i     yd  and 

analyses  oi  "">»<"'""=•;„,!,  it  of  the  protoxyds,  repre- 
siUca  remains  unchanged,  that  J  ^^^^^  ,,,„,i,, 

sented  by  alkalies,  IS  vaiiahle.  ,^^  physieally 

pear  in  the  t""'™'' "  XSmervariation,  in  the  ratio  ot 
similar  present,  at  tlie  ^"'^^iZ  that  of  alumina  to  sd.ca. 
pMoxyd-bases  to  »l"™»';;f;^^  Zlv^^on,  without  sen^- 
These  divergences  in  fT^^     ^^ovi  strong  arguments 

^^0^  i;:::r:lt^"'  »^  -^^  -^ «— '^ '-  ^^  "^ 

o,|d.metals,  on  the  »-  >>»'l;-f,  j^j  devices  have  been 
placing  elements,  on  the  ofter  .^  ^^  ,, 

proposed  by  ehemists,  °*  y'^^'jt^ue  letters  respectively. 
Ihe  employment  of  R;~?j!;''i,  „sed  for  an  atom  of 
Accordingly,  in  these  P^S^'  ehromicum,  bismuth. 


\' 


vin.] 


A   CLASSIFICATION    OK   SILICATKS. 


aia 


I 

li- 
te 
ch 
jes 
ger 
3ve, 

»UBO- 

n"ot- 

iiing 
.;  as 

ivgar- 

•eseut 

Eerent 

d  and 
vei)ve- 

lea  ap- 

■sically 

Iratio  of 

silica. 

X  sensi- 

•uments 

a  a  true 


of  m  :  si ;  tliose  of  tlio  iicM-siliciitcs,  m  :  si ;  and  those  of  the 
protopersiliciitcs,  in  :  m  :  si. 

§  47.  Having  sliovvn  the  wide  chemical  differences 
existing  between  tlie  three  great  divisions  of  the  (.rder 
Silicate,  we  [)roceed  to  consider  tiiose  dillerences,  alike 
chemical  and  physical,  which  are  found  hetween  species 
often  having  identical  or  similar  centesimal  composition. 
Physical  characters,  irrespective  of  chemical  composition, 
constitute,  in  the  language  of  Mohs,  the  "  characteristic  " 
of  mineral  species,  aiid  served  as  the  basis  of  his  system  of 
classification.  We  propose  to  show  that,  by  a  re-examina- 
tion of  these  characters  in  the  light  of  modern  chemistry, 
it  is  possible  to  devise  a  new  mineralogical  method,  which 
shall  letain  all  that  was  good  in  the  Natural  History 
System,  ai  I  at  the  same  time  bring  it  in  accordance  with 
the  facts  of  chemistry,  thus  giving  a  veritable  Natural 
System  to  Mineralogy. 

§  48.  The  great  divisions  marked  by  external  charac- 
ters were  made  by  Mohs  and  his  school  the  basis  of  a 
system  of  classification,  as  is  exemplified  in  his  orders  of 
Mica,  Spar,  and  Gem,  already  noticed  in  §§  5-6.  We 
have  there  seen  the  heterogeneous  nature  of  the  order 
Spar,  wherein  —  besides  the  genera,  Sehilltr-Spar  ;  Dis- 
thene-Spar,  including  cyanite  ;  Triphene-Spar,  comprising 
spodumene  and  prehnite ;  Petal ine-Spar,  for  petaiite  ; 
Azure-Spar,  for  lapis-lazuU  and  lazulite ;  Augite-Spar,  in- 
cluding pyroxene,  amphibole,  wollastonite,  and  epidote ; 
Felcl-iSpar,  embracing  adularia,  albite,  anorthite,  Icorado- 
lite,  and  scapolite  —  there  was  a  genus,  Kouphone-Spar,  in 
which  were  gi'ouped  not  only  leucite  and  sodalite,  but  the 
characteristic  zeolites,  mesotype,  laumontite,  harmotome, 
analcite,  chabazite,  stilbite,  and  heulandite.  With  these 
was  also  placed  apophyllite,  while  datolite  was  assigned  to 
another  genus,  Dystome-Spnr.  When,  in  1844,  Shepard 
divided  the  order  Spar,  by  the  separation  from  it  of  a  new 
order,  Zeolite,  he  transferred  to  this  the  whole  of  the 
species  of  the  latter  two  genera.      The  order  Spar  of 


6". 


■i* 


!  Mil 


.;M'fi:|; 


MMM 


mtm 


1*11*'  >  l< 


M' 


'J  1 


Cii 


314 


A   NATURAL   SYSTEM  IN   MINERALOGY. 


[VIII. 


Mobs,  and  the  united  orders  of  Spar  and  Zeolite  of 
Shepard,  thus  included  alike  protosilicates,  protopersili- 
cates,  and  persilicates  of  very  various  degrees  of  hardness 
and  chemical  unlikeness ;  since  not  only  datolite,  apophyl- 
lite,  and  pyroxene,  but  mesolite  and  stilbite,  leucite  and 
albite,  spodumene  and  epidote,  and  even  cyanite,  found  a 
place  therein.  A  still  more  heterogeneous  assemblage  was 
seen  in  Dana's  order,  Chalcinea,  which  comprised  not 
only  the  order  Spar  of  Mohs,  but  also  the  protopersilicate 
micas  of  his  order  Mica. 

§  49.  We  propose,  while  keeping  in  view  the  great 
chemical  sub-orders  already  defined  in  »ur  system,  to 
group  mineral  species  with  more  regard  to  these  external 
characters  than  has  hitherto  been  done.  The  obvious  dis- 
tinctions of  structure,  hardness,  and  density,  which  separate 
protopersilicates,  like  garnet,  staurolite,  and  tourmaline, 
from  the  micas,  on  the  one  hand,  and  from  the  feldspars, 
scapolite,  and  zeolites,  on  the  other,  though  but  imperfectly 
appreciated,  underlay  the  division  by  Mohs  into  Gem, 
Mica,  and  Spar,  and  the  necessity  of  a  sub-division  of  the 
sparry  or  spathoid  type  was  soon  felt  by  Shepard.  The 
need  of  this  is  most  apparent  in  the  great  sub-order  of 
the  protopersilicates,  where  it  will  be  seen  that,  alike  on 
chemical  and  physical  grounds,  the  natural  line  of  division 
coincides  with  that  betAveen  hydrous  and  anhydrous  spe- 
cies, —  the  latter  including  the  feldspars,  leucite,  sodalite, 
and  scapolites,  and  the  former,  or  hydrospathoid,  the  zeo- 
lites. A  similar  distinction  of  hydrous  and  anhydrous 
spathoids  is  equally  marked  in  the  protosilicates.  Upon 
the  foregoing  distinctions,  and  upon  the  still  farther  one 
which,  in  each  sub-order,  separates  all  these  crystalline 
species  from  amorphous  colloid  compounds,  we  may  pro- 
ceed to  divide  the  various  sub-orders  into  Tribes. 

§  50.  Beginning  with  the  Protosilicates,  we  recog- 
nize first  among  them  a  type  of  crystalline  hydrous  species, 
of  inferior  hardness  and  comparatively  low  density,  which 
are  decomposed  by  strong  acids  with  the  formation  of  a 


«♦ 


a 

ot 
ite 

eat 
to 
i-nal 
dis- 
irate 
iline, 
ipars, 
fectly 

ai  tlie 
The 
er  of 
ke  on 
tvvisiou 
s  spe- 
dalite, 
tie  zeo- 
ydvous 
Upou 
ler  one 
stalline 

ay  Pi'o- 

e  recog- 

species, 

ly,  wbicb 

lion  o£  a 


vm.] 


A  CLASSIFICATION  OF  SILICATES. 


315 


jelly,  or,  to  use  Graham's  phrase,  pectise  with  acids.  These 
hydrospathoids,  which  are  represented  by  pectolite,  apo- 
phyllite,  datolite,  calamine,  etc.,  may  be  conveniently 
designated  as  the  tribe  of  the  PectoiitoUh.  A  second 
type,  not  very  dissinnlar  lo  the  first,  but  somewhat 
harder,  and  anhydrous,  though  still  pectising  with  acids, 
is  represented  by  willemite,  tephroite,  helvite,  wollas- 
tonite,  etc.  These  anhydrous  spar-like  species  we  designate 
as  the  tribe  of  the  Protospathoids.  In  the  third  place,  we 
note  a  group  of  species  not  unlike  the  second  in  general 
aspect,  and,  like  them,  generally  anhydrous;  which  are, 
however,  harder,  and  considerably  denser,  as  appears  from 
the  reduced  value  of  V.  This  group  is  represented  by 
chondrodite,  chrysolite,  phenacite,  amphibole,  pyroxene, 
danburite,  titanite,  etc.  Many  of  these  species  present  a 
hardness  and  transparency  which  caused  them  to  be  in- 
cluded by  Mohs  and  his  school  in  the  order  Gem,  and  this 
gem-like  or  adamantoid  character  suggests  for  them  the 
tribal  name  of  Protadamantoids.  As  regards  their  rela- 
tion to  acids,  it  may  be  noted  that  while  the  spathoid 
wollastonite  is  readily  decomposed  thereby,  the  corre- 
sponding adamantoid  bisilicates,  amphibole  and  pyroxene, 
are  unattacked.  The  highly  basic  chrysolite  pectises  with 
acids,  but  the  more  condensed  phenacite  and  bertrandite, 
with  the  same  atomic  formula,  resist  their  action.  The 
case  of  titanite,  a  titanosilicate,  is  peculiar,  for  the  reason 
that  the  titanic  oxyd,  of  which  it  contains  so  large  a  pro- 
portion, is  soluble  in  chlorhydric  acid.  This  deconiposi- 
tion  of  titanite  was  long  ago  studied  by  the  writer,  who 
showed  that  the  titanic  oxyd  thus  dissolved  presents 
chemical  reactions  very  different  from  that  got  from 
menaccanite  by  the  same  solvent,  or  from  titanite  itself 
by  the  action  of  hot  sulphuric  acid,  and  then  described  it 
as  a  peculiar  modification  of  titanic  acid.* 

§  51.   We  recognize  in  the  fourtli  place  among  the  pro- 
tosilicates  a  group  characterized  by  a  hardness  less  than 
.  *  Araer.  Jour.  Science,  1852,  xiv.,  346. 


I 


W 


t  ?'  , 


iH 


li 


i.U 


ill 


316 


^  NATUBAL  SYSTEM  IN  MINEKALOGY. 


[VIII. 


bib  -^  ^^"   1    J 

tHatof  t.e  t,.ee  J^^S^ltX^^^ 
basal  cleavage,  y"'''!''*  ™X  foliated  sevpentiueB  H.  ^ 
^ell  seen  i.i  talc,  and  ">  the  i  j,^,jer,  is  largely 

lyve,  l.nt  sparingly  «  '-'"  "  ^^^^^  eWorites  ot  the  second, 
fevelopcd  in  t^>e  '""';'«  J^j'f,  „,;u,.aUy  designated  as 

Stay  Ue  ^^X^C'^^'^^  ff^ 
in  this  ordev  a  «'"«>'l<='*'; C  by  much  that  is  called  sei- 

chiefly  ™»g"^«>»\.?P'!!!"ute  chrysocolla,  etc.     To  these 
pentincbydeweyUe,  ee.ohte  c^^y^^^  ^^^^^^^^         ^ 

the  tribal   dos'gna"""  f      P  They  are,  for  the 

G,eek  name  for  ^"Te"*'"';;^  L  acids  witlrout  peotasa- 
rnost  part,  readdy  d^c"  "P^W  substances.  The  cryst"^" 
tion,  and  are  amorphous  collma  jj^;^,  i„  physical 

line  silicates  which  apP>^oach  thes^  ^^^  .^       ^^ 

and  chemical  eh»acters--m  pat  p^y^^^  .^  ^^^  j^^^,^,, 

nerhaps,  spathoids,— will  oe 

discussion  of  the  ophitoids.  ,„,,^,der,  that  of  the 

R  52.  Piissing  now  to  the  secona  ,<,to,iUoates, 

P Lov.KB,ucATES,  we  recognue.  as  .^^^^  J^^^  ^^ 

five  tribes,  which  ^oP^f.^^^/Jf  ti,e  great  family  of  the 

•ust  noticed.    The  fi.^t«*'"^^\  Jed  species,  wh.ch 

Lolites,  with  f  o^-"*;  ^"/^„  ;:thoid  tribe,  convemently 

together   constitute  a  ''jdre^P*  resemblances,  as  regards 

designated  as  ZeoUt^.d^-  J^^J^\,  „e,„,,ence.  between 

.  hardness,  density,  aspect,  MIC  m  pectolitoids  are 

this  tribe  of  hydrous     "/^j^e  difference  in  chemi- 
.uch  that,  -*-*tTi?eou:  pectolitoids  have  generally 

^3 ::2dtith  -  — ,„,er.  constituting  the 
"'The  spathoids  of  the  second  ^^  °  ,  ,,,ge  number  of 
tribe  of  the  •?"«»?/ '''"''itiMe,   gehlenite,  ilvaite,   the 


it 


VIII,] 


A   CLASSIFICATION   OP   SILICATES. 


317 


I 

s 
is 

d, 
as 
to- 
ins 
tes, 
ser- 
lese 
tlie 
•  the 
itisa- 
ystal- 
ysical 
,  part, 
iirther 

of  the 
Ucates, 
those 
of  the 
which 
nieixtly 
regivi'ds 
etweeTi 
Olds  are 
chemi- 
enerally 

iting  tlie 
[umber  of 
laite,   the 
leucite, 
lecies  are, 

^^,e  Proto- 


peradamantoids  form  a  large  and  important  tribe  of  hard 
and  gem-like  species,  inchiding  pargasite,  glaucophane, 
gastaldite,  idocrase,  garnet,  beryl,  euclase,  ardennite, 
axinite,  epidote,  spodumene,  sapphirine,  staurolite,  and 
the  tourmalines;  besides  allanite,  the  titanic  species, 
keilhauite  and  schorlomite,  and  the  remarkable  ferric 
species,  segirite,  acmite,  and  arfvedsonite.  These,  though 
differing  in  this  regard  among  themselves,  have  all  of 
them  a  more  condensed  molecule  than  the  densest  of  the 
spathoids,  and  it  is  to  be  noted  that  their  resistance  to 
acids  is  correspondingly  greater.  The  highly  basic  ada- 
mantoids  of  this  sub-order,  such  as  garnet,  epidote,  and 
zoisite,  are  not  attacked,  while  the  basic  spathoids  (as 
scapolites  and  feldspars)  are  readily  decomposed,  by  acids. 
The  phylloid  type  in  this  sub-order  is  represented  by  the 
great  group  of  the  micas  and  chlorites,  constituting  the 
tribe  of  Protoperphylloids  and  including  a  large  number 
of  species,  both  hydrous  and  anhydrous,  which  are  more 
condensed  than  the  spathoids,  though  less  so  than  the 
adamantoids. 

In  the  fifth  place,  we  find  the  uncrystalline  colloidal 
species  of  this  sub-order  represented  by  the  tribe  of  the 
Pmitoids,  named  for  the  typical  species,  pinite,  and  corre- 
sponding to  the  ophitoids,  with  which  they  have  man;" 
analogies.  This  tribe  includes  several  species  which  are 
essentially  hydrous  silicates  of  alumina,  with  more  or  less 
alkali.  With  the  true  pinitoids  are  probably  confounded 
other  substances  which  are  compact  forms  of  the  corre- 
sponding phylloids.  The  h3^drous  silicates  palagonite  and 
pitchstone,  and  the  anhydrous  tachylite  and  obsidian, 
though  not  definite  mineral  species,  are  placed  in  this 
tribe,  as  being  colloidal  protopersilicates. 

§  53.  The  hydrospathoid  and  spathoid  tribes  are 
scarcely  represented  among  the  less  protobasic  silicates  of 
the  second  sub-order,  and,  with  the  exception  of  westanite, 
which  seems  to  be  a  Pcrzeolltoid^  and  the  bismuthio 
silicates,  eulytite,  agricolite,  and  bismutoferrite,  apparently 


!• 


318 


A   NATURAL  SYSTEM  IN  MINERALOGY. 


[VIII. 


'J'    . 


I"  ' 


Perspathoids,  are  as  yet  unrecognized  in  the  sub-order  of 
the  Persilicates.  The  Peradamantoids,  however,  con- 
stitute an  important  tribe,  including  andalusite,  topaz, 
dumortierite,  fibrolite,  xenolite,  cyanite,  and  the  zircons. 
The  Perphylloid  tribe  is  rep'-'^sented  by  a  few  micaceous 
species,  such  as  pholerite,  talcosite,  kaolinite,  and  pyro- 
phyllite ;  while  the  uncrystalline  or  colloid  type  in  this 
sub-order,  which  we  have  designated  the  Argilloid  tribe, 
includes  the  various  clays  or  amorphous  hydrous  silicates 
of  alumina,  from  schrotterite  through  allophane  .aid  halloy- 
site  to  cimolite  and  smectite,  together  with  wolchonskoite 
and  chloropal. 

§  54.  In  the  preceding  scheme  it  will  be  seen  that  the 
first  place  has  been  given  to  the  great  chemical  distinctions 
which  are  embodied  in  the  three  sub-orders  of  silicates.  It 
might  be  thought  that  the  well  marked  physical  types  which 
we  have  seen  recurring  in  the  different  sub-orders  should 
be  made  the  ground  of  a  first  subdivision  of  the  order 
Silicate,  rather  than  the  chemical  distinctions  here  adopted. 
These  resemblances,  dependent  upon  similar  molecular 
aggregations,  and  upon  physical  structure,  are,  however, 
less  fundamental  than  those  based  upon  elemental  consti- 
tution. These,  as  we  have  sought  to  show,  are  genetic,  and 
should,  therefore,  have  assigned  to  them  a  greater  signifi- 
cance than  the  analogies  based  on  similarity  of  aggrega- 
tion and  structure,  which,  although  of  much  importance 
in  chissifica^ion,  are  essentially  mimetic.  The  foundations 
alike  of  the  order  and  the  sub-orders  are  wholly  chemical, 
and  the  division  of  each  of  the  sub-orders  into  tribes  is 
primarily  and  essentially  chemical  and  genetic.  On  the 
other  hand,  the  remarkable  resemblances  between  the  cor- 
responding tribes  in  the  different  sub-orders,  which  are 
chemically  distinct,  is  imitative  or  mimetic,  and  should, 
therefore,  be  assigned  a  subordinate  rank  in  classification. 

§  55.  In  arranging  still  farther  the  different  families, 
genera,  and  species  in  each  tribe,  the  question  arises,  what 
kind  of  chemical  variation  should  take  precedence.     Con- 


1i. 


VIII. 


A  CLASSIFICATION   OF   SILICATES. 


319 


a- 

IS. 

us 

ro- 

his 

ibe, 

ites 

Aoy- 

Loite 


sidering  the  general  persistence  of  type  in  series  of  proto- 
persilicates  like  those  of  the  zeolites  and  the  feldspars,  in 
each  of  which  the  ratio  of  protoxyds  to  alumina  is  con- 
stant, that  of  the  silica  being  variable,  I  have,  in  a  tabular 
view  of  the  sub-order,  arranged  species  so  related  on  the 
same  horizontal  lines;  while  species  belonging  to  the  same 
tribe,  but  having  different  relations  between  the  protoxyds 
and  the  alumina,  are  arranged  in  successive  horizontal 
lines ;  those  with  the  larger  proportion  of  protoxyds  being 
above,  and  those  with  the  smaller  proportion  below,  so  as 
to  represent  the  passage  towards  protosilicates,  in  the  one 
direction,  and  to  persilicates,  in  the  other.  It  should  here 
be  remarked  that  in  many  cases,  as  in  tourmalines  and  in 
micas,  the  species  thus  vertically  arranged  present  physi- 
cal resemblances  not  less  close  than  those  between  species 
on  the  same  horizontal  line,  within  the  tribe,  as  may  be  seen 
in  the  synoptical  table  of  the  protopersilicates,  mentioned 
below.  As  regards  the  relative  condensation,  the  suc- 
cessive species  or  genera  of  a  tribe  on  a  given  line  may 
be  placed  with  regard  to  the  value  of  V,  —  the  denser,  or 
those  with  the  lesser  atomic  volume,  following  those  which 
are  less  dense. 

§  56.  For  the  better  understanding  of  the  formulas 
given  in  the  accompanying  tables  of  the  various  tribes  of 
silicates,  it  may  be  well  to  recall  the  values  of  the  chemi- 
cal symbols  here  employed,  which  are  atomic,  —  the  small 
letters  representing  atoms  of  the  elements.  Hence,  while 
for  univalent  elements,  or  monads,  like  sodium,  chlorine, 
and  fluorine,  the  symbols  represent  the  received  molecu- 
lar weights,  these  weights  for  dyads,  like  glucinum,  cal- 
cium, ferrosum,  oxygen,  and  sulphur,  are  divided  by  two ; 
for  triads,  like  boron,  aluminium,  chromicum,  ferricum, 
manganicum,  and  bismuth,  by  three  ;  for  the  tetrads,  sili- 
con, titanium,  zirconium,  and  thorium,  by  four ;  and  for  a 
pentad,  like  niobium,  by  five.  Thus  the  numerical  values 
of  the  symbols  here  used,  hydrogen  being  unity,  are  as 
follows :  — 


A  NATUKAL  SYSTEM  IN  MINEKALOGY. 


IVIII. 


Atomic  Symbols  and  Weights. 


.  9.00 

.  8.00 

.  10.00 

.  19.00 

.  35.50 

.  7.00 

.  23.00 

.  39.00 


cs  . 

gl  . 
nig 
ca  . 
sr  . 
ba  . 
fe  . 
mn 


3.3.00 

cu  . 

.  31.05 

4.50 

ni  . 

.  20.00 

12.00 

zn  . 

.  32.50 

20.00 

ce  . 

.  47.00 

43.75 

yt  • 

.  44.50 

68.50 

b    . 

.     3.66 

28.00 

al  . 

.    9.00 

27.50 

cri 

.  17.33 

fl  . 

inni 
bi  . 
si  . 
ti  . 
zr  . 
th  . 
nb . 


18.66 
18.50 
69.33 

7.00 
12.50 
22.50 
58.00 
18.80 


§  57.  The  sub-orders  and  tribes  of  tlie  order  Silicate,  as 
already  set  forth,  are  here  presented,  and  are  followed  by 
a  list  of  the  principal  species  in  each  tribe.  The  several 
minerals  of  the  various  tribes,  in  their  sequence,  will  then 
be  briefly  noticed,  and  tables  of  them  will  be  given,  show- 
ing the  atomic  formulas  of  the  species,  and  the  values  of 
P  and  V  as  calculated  therefrom.  For  the  crystalline 
tribes,  the  form,  when  known,  will  be  designated  in  these 
tr,bles  under  X,  initial  letters  being  used,  as  follows :  I, 
Isometric ;  T,  Tetragonal ;  O,  Orthorhombic ;  C,  Clino- 
rhombic ;  A,  Anorthic  or  Triclinic ;  H,  Hexagonal,  and 
R,  llhombohedral. 

This  will  be  followed,  in  a  fourth  part  of  the  essay,  by  a 
brief  discussion  of  the  non-silicated  oxyds  or  Oxydates, 
and  the  non-oxydized  metallic  ores  or  Metallates,  together 
constituting  two  additional  orders,  the  places  of  which  are 
then  assigned  in  a  general  scheme  of  classification  that 
includes  all  native  mineral  species.  Following  this,  is  a 
discussion  of  the  question  of  molecular  weights,  and  its 
bearing  on  a  new  departure  in  chemistry.  Finally,  the 
principal  minerals  of  each  sub-order,  arranged  under  their 
respective  tribes,  in  the  sequence  already  explained,  will 


It 


ate,  as 
vedby 
several 
ill  then 
^,  sbow- 
lalues  of 
stalline 
^1  these 

o\vs".  ^-1 
,,  CUno- 
nal,  and 


VIII.] 


A  CLASSIFICATION  OF  SILICATES. 


821 


be  presented  in  synoptical  tables,  giving  at  a  single  view 
the  new  classification  of  the  silicates.* 

Order  SiLtrATE. 

StTB-OBDEB  I.     PkoTOSILICATB. 

Tribe  1.  Hydroprotospathoid  (Pectolitoid). 

Tribe  2.  Protospathoid. 

Tribe  3.  Protadaniantoid.  , 

Tribe  4.  Protophylloid. 

Tribe  5.  Protocolloid  (Ophitoid). 

Sub-Order   II.      Protopersilicatb. 

Tribe   6.  Hydroprotoperspathoid  (Zeolitoid). 

Tribe   7.  Protoperspathoid. 

Tribe   8.  Protoperadainantoid 

Tribe   9.  Protoperphylloid. 

Tribe  10.  Protopercolloid  (Pit  toid). 

SUB-OrDEB  III.      PiJBSILICATE. 

Tribe  11.  Hydroperspathoid  (Perzeolitoid). 

Tribe  12.  Perspathoid. 

Tribe  13.  Peradaraantoid. 

Tribe  14.  Perphylloid. 

Tribe  15.  Percolloid  (Argilloid). 

Tribe  1.  Pectolitoid.  Calamine,  Thorite,  Cerite,  Gyrolite,  Friede- 
lite,  Pyrosmalite,  Xonaltite,  Plombierite,  Dioptase,  Pectolite,  Datolite, 
Apopliyllite,  Okenite ;  together  with  Villarsite,  Matrieite,  Picrosmine, 
Picrolite,  and  Chrysotile.     (Table  I. ) 

Tribe  2.  Protospathoid.  Danalite,  Willemite,  Batrachite,  Tephro- 
ite,  Knebelite,  Gadolinite,  Helvite,  Leueophanite,  Wollastonite, 
Tscheffkinite.    (Table  II. ) 

Tribe  3.  Protadamantoid.  Chondrodite,  Monticellite,  Chrysolite, 
Phenacite,  Bertrandite,  Amphibole,  Rhodonite,  Pyroxene,  Enstatite, 
Guarinite,  Titanite,  Danburite.     ( Table  III. ) 

Tribe  4.  Protophylloid.  Thermophyllite,  Marmolite,  Talc.  (Ta- 
ble IV.) 

Tribe  5.  Ophitoid.  Serpentine,  Retinalite,  Deweylite,  Genthite, 
Aphrodite,  Cerolite,  Chrysocolla,  Spadaite,  Rensselaerite,  Sepiolite, 
Glauconite.     ( Table  V. ) 

*  As  regards  the  designation  of  the  tribes,  the  use  of  a  term  which 
ends  in  a  syllable  expressing  likeness,  to  include  not  only  bodies  resem- 
bling a  given  type,  but  the  type  itSelf,  is  justified  by  the  meaning  given 
to  such  words  as  haloid,  albuminoid,  and  colloid,  and  also  by  the  use  in 
botany  of  the  name  of  Aroideos  for  an  order  which  comprises  not  only 
Araceae,  but  the  typical  genus  Arum. 


1 

1 

T 

m 

y 

iSwi' 

i 

fiSI 

k 

^^^^V   1 

1*" 


822 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


tvin. 


.  I  ■'. 


Tkibe  6.  Zeolitoid.  Xanthorthite,  Hamelite,  Catapleilte,  the  various 
Zeolites;  wltli  Cancrlnite  ai  i  Ittnerite,  Edlngtonite,  Sloanite, 
Forestlte.     ( Table  VL) 

Tbide  7.  PnoTOPEKSPATHOiD.  Melilitc,  Eudialyte,  Wohlerite,  Hum- 
boldtllite,  Ilvalte,  Gehlenite,  Sarcolite,  Mllarite,  Barylite,  Meionite, 
with  Marialite  and  intermediate  Scapolites,  Sodalite,  Nosite,  Hauyne, 
Lapis-lazuli,  Leuclte,  Hyalophane,  Orthoclase,  Microcllne,  Neplielite, 
Paranthite,  Eucryptite,  Anorthite,  Albite  and  intermediate  Feld- 
spars, lolite,  Petailte.     (Table  VII. ) 

Tribe  8.  Protopebadamantoid.  Pargasitc,  Eeilhauite,  Idocrase, 
Glaucophane,  Schorlomite,  Garnet,  -.Egirite,  Allanite,  Beryl,  Euclase, 
Prehnile,  A-rfvedsonite,  Ardennite,  Axinite,  Epidote,  Zoislte,  Jadeite, 
Gastaldite,  Acmite,  Spodumene,  Sapphirine,  Staurolite;  and  the 
Tourmalines,  including  Coronite,  Schorlite,  Aphrizite,  Indieolite, 
Rubellite.    (Tar'eVIIL) 

Tbibe  9.  Pbotopebphylloid.  Astrophyllite,  Phlogopite,  Pyroscle- 
rite,  Penninite,  Ripidolite,  Prochlorite,  Cronstedite,  Leuchtenbergite, 
Venerite,  Corundophilite,  Biotite,  Voigtlte,  Cryophylllte,  Seybertite, 
Thuringite,  Jefferisite,  Annite,  Willcoxite,  Chlorltoid,  Lepidomelane, 
Zinnwaldite,  Oellaclierite,  Lepidollte,  Margarlte,  Euphyllite,  Cooke- 
ite,  Damourite,  ParagOiilte,  Muscovite.     (Table  IX.) 

Tbibe  10.  Pinitoid.  Jollyte,  Fahlunite,  Esmarkite,  Bravaisite,  Sorda- 
valite,  Hygrophllite,  Pinite,  Cossaite;  with  Palagonite,  Tachylite, 
Pitchstone,  and  Obsidian.     ( Table  X. ) 

Tbibe  11.  Perzeolitoid.    No  species  known  except  perhaps  Westanite. 

Tbibe  12.  Perspathoid.  No  species  known  to  represent  this  tribe 
except  Eulytite  and  other  related  bismuthic  silicates. 

Tribe  13.  PEBADAMANTOin.  Dumortierite,  Topaz,  Andalusite,  Fibro- 
lite,  Cyanite,  Bucholzite,  Xenolite,  Worthite,  Lyncurite,  Malacone, 
Zircon,  Auerbachite,  Anthosiderite.     ( Table  XI. ) 

Tbibe  14.  Perpuylloid.  Pholerite,  Talcosite,  Kaolinite,  Pyiophyllite. 
(Table  Xn.) 

Tbijb  15.  Abgilloid.  Schrotterite,  Collyrite,  Allophane,  Samoite, 
Halloysite,  Kaolin,  Keramite,  Hisingerite,  Wolchonskoite,  Montmor- 
lUonite,  Chloropal,  Cimolite,  Smectite.    (Table  XIII.) 


Tribe  1.  Pectolitoid. 
§  58.  We  notice  first  in  this  tribe  the  hydrated  sili- 
cates of  lime,  often  with  alkali,  most  of  which  are  fre- 
quently found  among  the  secretions  of  basic  rocks,  and 
which  include  pectolite,  xonaltite,  gyrolite,  plombierite, 
datolite,  okenite,  and  apophyllite.  The  name  selected  for 
the  tribe  recalls  at  the  same  time  the  most  common  of 
these  species,  and  also  the  property  which  belongs  to 
most  of  them  of  pectising  or  being  decomposed  by  strong 


VIIIO 


A  CLASSIFICATION  OP  SILICATES. 


323 


us 
te, 

im- 
ilte, 
yne, 
jUte, 


acids,  such  as  chlorhydric,  with  the  separation  of  gelati- 
nous silica.*  It  has  also  the  advantage  of  distinguishing 
them  from  the  zeolitoids,  the  corresponding  type  in  the 
next  sub-order,  with  which  they  are  generally  associated, 
and  sometimes  confounded.  Differing  considerably  in  the 
proportion  of  combined  water,  the  pectolitoids  have  a 


irase, 

iclase, 

idelte, 

d  t^e      . 

IcoUte, 

yrosc\e- 

ybertite, 

,  Cooke- 

,e,  Sorda- 
lacbyWe, 

'estanite. 
this  tribe 

Malacone, 

Satoolte, 
['  Montmor- 


Table  I.  —  Pbctolitoids. 


Species. 

Formula. 

P 

D 

V 

.! 

Calamine      .    .    . 

(zn,8i,)o,  -f-  Jaq 

24.00 

3.60 

6.87 

0. 

Thorite    .     . 

(th,si,)Oj-(-Jaq 

32.62 

5.30 

6.16 

I. 

Cerite  .    .    . 

(ceiSi,)oj-f-Jaq 

29.80 

4.90 

6.08 

P 

Gyrolite  .    .    . 

(ca,8i3)06-|-laq 

18.33 

.... 

.... 

P 

Friedelite     .    . 

(mnj8i3)06  -\-  2aq 

19.14 

3.07 

6.23 

R. 

Pyrosmalite 

(fea8i3)0s  +  laq 

21.68 

3.17 

6.80 

H. 

Chrysotile     . 

(mg3si4)0:  +  2aq 

15.33 

2.22 

6.98 

P 

Xonaltite 

(caisi,)os-f-{aq 

18.53 

2.71 

6.83 

p 

Flombierite 

(caisij)03  +  2aq 

15.20 

•  •  •  • 

•  •  •  • 

P 

Dioptase  .    . 

(cnisij)08  +  laq 

19.67 

3.34 

6.88 

R. 

Pectolite  .    . 

(cassiij)iK  +  laq 

18.27 

2.78 

6.57 

C. 

Datolite   .     . 

(cas8i4b3)oo  +laq 

16.00 

2.99 

6.35 

C. 

Apophyllite  . 

(ca,8i4)Os  +  2aq 

16.14 

2.35 

6.44 

T. 

Okenite   .    .    , 

(c^si4)04  +  2aq 

15.14 

2.35 

6.44 

0. 

hardness  below  that  of  quartz,  and,  with  but  few  excep- 
tions, a  comparatively  large  atomic  volume.  In  the  case 
of  apophyllite  a  little  fluorine  is  present,  and  in  datolite  a 
large  amount  of  boric  oxyd,  which  in  our  atomic  formula 

*  The  name  pectolite  is  said  to  be  from  the  Latin  pecten,  in  alhision 
to  the  comb-like  structure  of  some  varieties  of  the  mineral,  but  it  at  the 
same  time  suggests  the  Greek  thjxtos  (curdled  or  congealed),  from  which 
have  been  derived  the  chemical  terras  pectose  and  pectin,  and  the  verb 
to  pectise,  employed  by  Graham  to  denote  the  gelatinizing  property  of 
certain  substances. 


Ik 


324 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VIII. 


is  represented  as  replacing  a  portion  of  silica.  They  are 
all  native  species,  some  of  which  'lave  also  been  artificially 
formed,  and  at  least  one  of  them,  apophyliite,  is  found  of 
recent  origin  in  the  channels  of  the  thermal  waters  of 
riombi^rcs,  in  France,  where  another  species,  plombierite, 
his  also  been  met  with.  An  unnamed  pectolitoid  was 
got  by  Daubr(;e  as  a  pioduct  of  the  action  of  super- 
heated water  on  glass.  Delonging  to  this  same  tribe  are : 
the  zinc-silicate,  calamine ;  the  rare  species,  thorite  and 
cerite ;  the  manganeslan  silicate,  friedelite ;  pyrosmalite, 
a  ferro-manganesian  species  containing  ciilorino ;  and  the 
copper-silicate,  dioptuse.  The  composition  of  tritomite  is 
not  certain,  but  appi  caches  that  of  cerite.  Here,  also, 
mosandrite  probably  belongs. 

§  69.  We  place  here  also  chrysotile,  which  constitutes 
the  common  amianthus,  and  has  hitherto  been  regarded 
as  a  variety  of  serpentine,  with  which  it  agrees  in  centesi- 
mal composition.  It  is,  however,  distinguished  therefrom 
by  a  lower  specific  gravity,  and  by  its  fibrous  character, 
which,  like  that  of  ar.uanthoid  amphibole,  indicates  a  pris- 
matic crystallization.  As  will  be  shown  farther  on,  at 
least  two  other  species,  one  phylloid,  and  another  ophitoid, 
have  been  confounded  under  the  name  of  serpentine. 
While  the  density  of  these  last  is  2.60,  or  higher,  that  of 
chrysotile,  according  to  three  determinations,  is  2.142, 
2.220,  and  2.238,  the  first  and  the  last  of  these  being  by 
E.  S.  Smith,  and  according  to  his  analyses,  corresponding  to 
specimens  containing  respectively  2.23  and  3.36  of  ferrous 
oxyd.*  If  this  oxyd  be  to  the  magnesia  as  1 :  30,  it  would 
give  for  P  a  value  of  16.51,  which,  with  a  density  of  2.22, 
would  make  V=6.98. 

Fibrous  silicrles  having  the  same  centesimal  composition 
as  the  last  are,  however,  met  with,  having  a  much  higher 
specific  gravity.  A  well  defined  mineral,  described  many 
years  since  by  the  writer,  from  Bolton  (Quebec),  under  the 
name  of  picrolite,  is  separable  into  long,  rigid,  elastic 

*  Amer.  Jour.  Science,  1885,  xxix.,  32. 


!♦ 


LI. 

re 

o£ 

o£ 

•ite, 

iper- 
are : 
and 
lalite, 
d  the 
nite  is 
,  also, 

ititutes 

jgarded 

centeai- 

leveirom 

lavacter, 

;s  a  pris- 

sr  on,  at 
)phitoid, 

jrpentine. 

L  that  oi 
is  2.142, 
being  by 
ponding  to 
oi  ierrous 
)  itwonld 
ty  of  2.22, 

imposition 
iclx  bigl^er 
tibed  many 
,^^ndertbe 

Igid,  elastic 


vm.i 


A   CLASSIFICATION   OP   SILICATES. 


325 


fibres,  and  lias,  with  a  specific  gravity  of  2.G07,  the  com- 
position, silica  43.70,  iimguesia  40.68,  forroua  oxyd  3.51, 
with  traces  of  oxyds  of  nickel  and  chromium,  and  12.45 
of  water,  =  100.34.* 

§  60.  While  the  above  species  of  unlike  density  agree 
in  having  the  serpeiitine  ratio,  3:4:2,  there  are  several 
other  hydrous  silicates  of  magnesia  which  present  other 
ratios,  and  should,  like  these,  be  included  among  hydro- 
spathoids.  Such  are  the  orthorhombic  sparry  villarsite, 
with  D  =  2.98,  which  has  been  described  as  a  hydrous 
chrysolite,  and  is  represented  by  the  atomic  formula 
(mgi8ii)o3-}-^aq;  and  the  fibrous  crystalline  matricite,  with 
I)  =  2.53,  more  hydrous  in  composition,  with  the  formula 
(mgisix)o2-l-laq,  nearly.  The  sparry  orthorhombic  picros- 
mine,  with  D  =  2.66,  which  is  sometimes  fibrous  and 
asbestiform,  is  a  hydrous  bisilicate,  represented  by 
(mgisi2)o3-|-^aq,  and  Terrell  has  very  recently  described 
as  chrysotile,  from  an  unnamed  locality  in  Canada,  with 
D=  2.56,  an  asbestiform  silicate,  which  is  at  once  more 
basic,  more  hydrous,  and  heavier  than  ordinary  chrysotile, 
and  approaches  matricite  in  composition.  His  analysis 
gives  silica  37.10,  magnesia  39.94,  ferrous  oxyd  5.73,  alu- 
mina, traces,  water  10.85=: 99.62.  This  corresponds  very 
closely  to  (mg(5.5feo.5si8)oi5-f-6aq.t  These  various  prismatic 
hydrous  silicates  of  magnesia,  including  chrysotile  and 
picrolite,  constitute  an  important  group  of  what  may  be 
designated  as  magnesian  pectolitoids,  which  have  for  the 
most  part  an  atomic  volume  approaching  to  dioptase  and 
to  datolite,  and  demand  farther  study,  but,  with  the  excep- 
tion of  chrysotile,  have  not  been  placed  in  our  table. 

§  61.  In  the  accompanying  table  (No.  I.)  of  the  prin- 
cipal pectolitoids,  are  given  their  atomic  formulas  as 
deduced  from  chemical  analysis,  the  unit-weight,  P,  cal- 
culated from  these,  the  density,  D  (water  =  1.00),  and  the 
atomic  volume,  V,  which  =  P  -;-  D.     ^n.  calculating  the 

*  Geology  of  Canada,  ISfiS,  p.  472. 

+  Coiupte  lleiulu  Ue  "Acad,  des  Sciences,  January  26,  1885. 


i 


l« 


A  NATURAI.  SYSTEM  IN  MINER ALOOY. 


tviii. 


value  of  P  for  these  silicates,  we  have  to  consider  that 
two  or  more  protoxyd-bases  are  often  present,  and  that 
the  proportions  of  these  must  be  estimated  as  nearly  as 
possible.  As  the  specific  gravity  of  species  is  in  many 
cases  inexactly  determined,  we  have,  where  more  than 
one  value  of  D  is  given  by  mineralogists,  selected  tliat 
which  seemed  most  probably  correct,  and,  where  determi- 
nations of  density  are  wanting,  have  left  a  blank  in  the 
table.  Of  the  species  in  this  table,  datolite  is  a  borosili- 
cate,  pyrosmalite  a  chlorosilicate,  and  apophyllite  a  fluoro- 
silicate. 

§  G2.  It  has  been  thouglit  well,  for  reasons  which  will 
be  apparent  when  we  compare  the  pectolitoids  with  other 
tribes,  to  represent  their  contained  water  by  the  symbol 
aq,  preceded  by  the  sign  -}-•  It  will  be  noted  that  in  the 
atomic  formulas  here  employed,  the  symbols  of  the  metals, 
with  those  of  silicon,  boron,  and  titanium,  afe  placed 
within  parentheses,  and  those  of  oxygen,  sulphur,  fluorine, 
and  chlorine,  together  with  water,  without.  From  this  it 
will  be  clear  that  the  atomic  weight  deduced  from  these 
formulas  must,  in  order  to  arrive  at  P  (the  weight  of  the 
atomic  unit),  be  divided  by  the  number  of  these  units; 
that  is  to  say,  by  the  sum  of  the  coefficients  of  the  ele- 
ments outside  of  the  parenthesis.  The  present  table  is  far 
fiom  complete ;  the  determinations  of  density  are  in  many 
cases  uncertain,  those  assigned  to  the  same  species  by  dif- 
ferent observers  often  presenting  wide  variations.  Again, 
the  value  of  P  in  cerite  is  calculated  as  if  it  were  simply  a 
silicate  of  cerium,  while  it  contains  unknown  proportions 
of  lanthanum,  didymium,  and  samarium.  In  calculating 
the  value  of  P  for  pyrosmalite,  it  is  regarded  as  a  ferrous 
silicate  in  which  p^  is  replaced  by  cl|,  equal  to  3.46  of 
chlorine.  The  general  agreement  in  the  value  of  V  is 
noticeable,  save  in  two  cases, —  that  of  dioptase,  for  which 
another  recorded  determination  of  D  =  3.28  gives  V=  6.00, 
and  that  of  datolite,  whose  volume  shows  a  condensation 
approaching  to  that  of  the  adamantoid  protosilicates. 


w 


•(A 


VIII. 


A  CLASSIFICATION  OF   SILICATES. 


827 


.t 
it 

an 
i\at 
lui- 
t\ie 

.»iU- 
Loro- 

i  wiU 
other 

in  tVie 
netalSi 
placed 
uori^e, 

this*  it 
ft  these 

of  the 

units; 
[the  ele- 

Ae  is  far 
tn  niany 
Is  by  dif- 
^gain, 

isimp^y  '^ 
kportions 

[iculating 

la  iervous 

3.46  of 

p  of  V  is 

[for  which 

V  =  6.00, 

.densatiou 

jates. 


Tribe  2.  Protospathoid. 
§  68.  In  the  second  tribe,  whicli  wo  have  called  Proto- 
spathoids,  shown  in  tuhlo  No.  II.,  are  tlie  sparry  silicates 
of  zinc  and  manganese,  willoniite  and  tephroite,  and  the 
ferro-niangane«uin  species,  knebelite, —  all  having  the  ratio 
of  unisilicates.  To  these  are  joined  tlie  iloiihlo  silicate  of 
lime  and  magnesia,  batrachite,  with  gadolinite,  a  silicate 

TaBLK    II.  —  PuOTOSPAXnOIDS.* 


Species. 


Form  i;  LA. 


Danalite.  -  - 
Willemite.  - 
Batrachite.  - 
Tephroite.  -  - 
Knebelite.  -  - 
Gadolinite.  - 
Helvite.  -  - 
Leucophanite. 
Wollaatonite.  - 
Tscheffkinite. 


(m,8ig)o„  -  (m  =  gl,  fe,  an) 

(zn,8ii)o, 

(m,8i,)o,  -  (m  =  cao.smgo.5) 
(innisi,)0j      -    -    -    -    - 
(m,8ii)0j  -  (m  =feo.5mno.5) 
(mi8i,)o,  -  (m  =gK  yt,  fe) 
(mi8ii)0j  -  (m  ==  gl,  mn)  - 
(mjsiiioT  -  (m  =  gl,  ca,  na) 

(ca,8ij)o, 

(m,sij)os  -  (m  s=  ce,  ca,  fe) 


22.15 
27.75 
19.50 
25.25 
25.37 
25.60 
20.16 
18.05 
10.33 
27.00 


D 


8.43 
4.18 
3.03 
4.12 
4.12 
4.20 
3.30 
2.97 
2.92 
4.26 


0.76 
0.63 
6.43 
6.13 
6.15 
«.10 

6.r 

6.07 
6.62 
6.34 


I. 

n. 
o. 
o. 

o. 

1. 
o. 
c. 
? 


chiefly  of  yttria,  giving  apparently  the  same  atomic  ratios, 
and  helvite,  a  silicate  of  glucina  and  manganese,  remark- 
able for  containing  a  large  amount  of  sulphur ;  in  which 
respect  it  resembles  the  more  basic  silicate  of  glucina, 
iron  and  zinc,  danalite,  belonging  to  the  same  tribe. 
With  these  are  also  placed  leucophanite,  which  is  interest- 
ing as  being  a  fluoriferous  silicate  of  glucina,  lime,  and 

*  The  formulas  employed  in  calculating  the  values  of  P  and  V 
for  the  following  species  are 

a.  Danalite  —  (gl3.ofe3.onino.5zni,68i8  ,,)oi9.oSi.o. 

6.  Gadolinite  —  (gl».noyt2.oofeo.T6ceo.26si4.oo)oB.w  . 

c.  Leucophanite  —  (ca5.ogl5.onaa,o.«:ij.o)o»8.o' 

d.  Tscheffkinite — [Damour]  (ce9.i»feo,»(,ca^.,6si,.aotio.7o)Qi.oo. 


328 


A  NATURAL  SYSTEM   IN   MINERALOGY. 


[VIII. 


soda,  having  the  same  atomic  ratio  for  its  bases  as  serpen- 
tine and  chrysotile.  Among  bisilicates  we  find,  in  this 
tribe,  wollastonite,  a  simple  lirae-silicate,  and  tscheffkinite, 
a  titanosilicate  of  lime  with  cerous  and  ferrous  oxyds. 
All  of  the  silicates  of  this  tribe  are  decomposed  by  acids 
with  pectisation. 

Tribe  3.  Protadamantoids. 
§  64.  We  next  proceed  to  note  the  adamantoid  proto- 
silicates  or  Protadamantoids,  closely  connected  with  the 
Protospathoids,  but  distinguished  from  them  by  a  more 
condensed  molecule  and  a  greater  resistance  to  acids. 
First  in  order  comes  the  fluoriferous  magnesian  silicate, 
chondrodite,  next  the  double  silicate  of  lime  and  magnesia, 
monticellite  (which,  from  its  recorded  specific  gravity, 
would  seem  to  be  a  denser  silicate,  isomeric  with  the  spath- 
oid  batrachite),  and  the  chrysolites,  belonging  to  a  more 
condensed  type  than  either.  The  genus  chrysolite  in- 
cludes not  only  the  ordinary  more  or  less  ferrous  species, 
but  forsterite,  on  the  one  hand,  and  hortonolite  and  fayalite, 
on  the  other.  To  this  succeed  the  two  glucinic  species, 
phenacite  and  bertrandite,  the  former  of  which  is  the  most 
highly  condensed  protadamantoid  known,  while  the  latter 
is  remarkable  for  containing  a  portion  of  water.  Next  in 
order  comes  the  manganesian  species,  rhodonite,  together 
with  the  amphiboles  and  pyroxenes,  two  important  genera, 
or  rather  families,  which  (with  the  apparent  exception  of 
certain  amphiboles  having  the  atomic  ratio  of  bases  to 
silica  of  4  :  9)  are  bisilicates.  While  rhodonite  and  pyrox- 
ene are  clinorhombic  in  crystallization,  the  magnesian 
species  enstatite,  with  hypersthene  and  diaclasite,  is  or- 
thorhombic.  Anthophyllite  appears  to  be  an  ortho- 
rhombic  species  having  the  composition  of  amphibole,  and 
kupfferite,  a  magnesian  amphibole.  Their  very  varied 
composition,  and  the  great  number  of  bases  which  enter 
into  the  composition  of  some  of  the  amphiboles  and  the 
pyroxenes,  are  illustrations  of  the  polybasic  character  of 


..  ^ 


I- 

is 

>e, 

Is. 

ds 


VIII.] 


A  CLASSIFICATION  OF   SILICATES. 


329 


the  silicates.  With  the  pyroxenes,  some  mineralogists 
have  grouped  spodumene,  gegirite,  arfvetlsonite,  and  acmite, 
the  association  being  based  on  similarity  of  crystalline 
form,  and  supported  by  a  misconception  of  their  chemical 
relations.     All  of  these  species  find  their  position  in  the 


''  '"ill 


['•■:re 


Table  III.  —  Pkotauamantoids. 


Lte  in- 


.e 


Spbcihb. 

Formula. 

F 

D 

V 

X. 

Chondrodite.  -    - 

(mg^Bia)©; 

18.64 

3.20 

5.82 

0. 

Monticellite.  -    - 

(misil)©.,  -  (m  =  mgo-jcao-s)  -    - 

19.50 

3.25 

6.00 

0. 

Forsterite.     -    « 

(mgisijoj 

17.50 

3.30 

5.30 

0. 

Chrysolite  (1).    - 

(miBii)Oi,  -  (m  =  mgo.»feo.i   -    - 

18.30 

3.40 

5.38 

0. 

Chrysolite  (2).    - 

(misi J02  -  (m  =  mgo-gfeo-j    -    - 

19.10 

3.50 

5.45 

0. 

Bertrandite.  -    - 

(gli8i:)02+Jaq 

13.22 

2.59 

5.10 

0. 

Phenacite.      -    - 

(g^lSJiK 

15.75 

3.00 

4.58 

R. 

Amphibole  (1).   - 

(mi8ij)03  -  (m  =  mgo.75,cao.25)  - 

17.33 

2.97 

5.88 

C. 

Amphibole  (2).  - 

(misij)03  -  (m=mgo.6cao.3feo.i)- 

18.00 

3.00 

5.88 

C. 

Rhodonite.     -    - 

(mnisi2)o, 

21.83 

3.00 

6.06 

C. 

Pyroxene  (1)      - 

(misij)03  -  (m  =  cao-smgo-s)  -    - 

18.00 

3.27 

5.50 

C. 

Pyroxene  (2).     - 

(misi2)03  -  (m  =  cao.5mgo.5)  -    - 

18.00 

3.28 

5.48 

C. 

Pyroxene  (3).     - 

(m,8i2)0s  -  (m  =  cajmgs)    -    - 

17.55 

3.22 

5.45 

C. 

Pyroxene  (4).     - 

(mi8i2)03  -  (m  =  cajmgffe J)    - 

18.66 

3.41 

5.47 

c. 

Enstatite  (1).      - 

(mi8i2)o3  -  (m  =  mgo-gfeo-i)  -    - 

17.20 

3.10: 5.54 

1 

0. 

Enstatite  (2).     - 

(m,si2)03  -  (m  =  mgo.gfco.j''  -    - 

17.73 

3.25  5.45 

0. 

Titanite.    -    -    - 

(ca,8iiti2)05 

19.80 

3.50  5.65 

c. 

Guarinite.  -    -    - 

(oaisi2ti2)o5 

19.80 

3.50  5.65 

1 

T. 

Danburite.     -    - 

(cai8i4b3)08 

15.37 

3.00|  5.12 

0. 

next  sub-order,  and  the  place  of  the  last  three  is  near  to 
garnet  and  to  epidote.  We  have  already  shown,  in  §  42, 
how,  on  similar  grounds,  the  aluminous  species  pargasite, 
glaucophane,  and  gastaldite  have  been  erroneously  placed 
with  amphibole. 


tammm 


330 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VUL 


*;  .* ' 


(i!;!: 


§  65.  The  relations  of  amphibole  and  pyroxene  to  each 
other  and  to  wollastonite,  as  shown  in  the  unlike  degrees 
of  condensation  made  evident  by  the  different  values  of 
V,  were  pointed  out  by  the  present  writer,  in  1853,  as  ex- 
amples of  isome-ism  in  polysilicates,  when  the  three  were 
represented  as  belonging  to  as  many  homologous  types 
(§  18).  These  relations,  so  far  as  amphibole  and  pyrox- 
ene are  concerned,  were  mentioned  some  years  later  by 
Dana,  in  1868,  when  he  noticed  that  the  pyroxenes  have  a 
spccitic  gravity  about  one  tenth  greater  than  that  of  the 
corresponding  amphiboles.*  The  chemical  difference 
between  these  species  and  the  corresponding  spathoids  is 
seen  in  the  resistance  of  both  amphibole  and  pyroxene 
to  acids,  which  decompose  wollastonite.  Rhodonite, 
a  manganesian  species  with  the  crystalline  form  of 
pyroxene,  appears,  from  its  volume,  to  be  more  closely 
related  to  amphibole,  and  is  partly  decomposed  by 
acids.  Different  and  unlike  varieties  of  pyroxene  agree 
closely  with  each  other,  with  enstatite,  and  with  chryso- 
lite, in  the  value  of  V,  as  will  be  made  evident  by 
ihe  accompanying  table.  No.  III.  In  this,  the  four 
pyroxenes  compared  were  examined  and  analyzed  by  the 
writer. 

To  this  tribe  of  Protadamantoids  we  add  titanite  and 
guarinite,  two  titanosilicates  of  unlike  crystalline  form, 
but  of  identical  composition  and  specific  gravity.  The 
solubility  of  titanitt  in  acids  has  already  been  noticed,  in 
§  57.  Here,  also,  is  the  place  of  danburite,  a  borosilicate, 
remarkable  for  having  a  value  of  V  near  to  that  of  the  pec- 
tolitoid  borosilicate,  datolite.  The  amphiboles,  rhodonite, 
chondrodite,  and  monticellite,  are  the  adamantoids  which 
approach  nearest  to  the  spathoids,  from  the  denser  species 
of  which,  tephroite,  hel .  ite,  and  leucophanite,  they  are 
not  far  removed  in  volume. 


*  System  of  Mineralogy,  5th  ed.,  p.  240. 


;• 


I. 

lb 

es 
ot 

JX- 

ere 
pes 
•ox- 

ve  a 

the 

ence 

ds  is 
)xene 
onite, 
m    of 
jlosely 
ed   by 
5  agree 
chryso- 
ent  by 

e  iour 

by  ^'be 

Lite  and 
[e  form, 
y.    The 

Iticed,  in 
)silicate, 
tbe  pec- 
lodonite, 
Is  wbicb 
jsr  species 
tbey  are 


VIU.] 


A  CLASSIFICATION  OF  SILICATES. 


331 


Tribe  4.  Protophijlloids. 
§  66.  The  phylloid  type  in  the  protosilicates  is  repre- 
sented by  a  small  number  of  magnesian  minerals,  of  which 
the  best  known  is  talc,  apparently  including  two  species 
with  different  atomic  formulas,  but  indistinguishable  save 
by  chemical  analysis.  To  these  must  be  added  one  or 
more  of  the  species  generally  classed  under  the  head  of 
serpentine.  Among  them  is  thermophyllite,  having  a 
recorded  density  of  2.56-2.61,  while  marmolite,  with  a  simi- 
lar composition,  should,  if  its  density  be  really  2.41,  con- 
stitute   another    Protophylloid   species,   as  indicated  in 

Table  IV.  —  PROTOPHYLLOios. 


Species. 

FOBMULA. 

P 

D 

V 

X. 

Thennophyllite. 
Marmolite.     -    - 
Talc.     .... 
Tala     -    -    -   - 

(mgjsii)©,  +  2aq     - 
(mg3si>j  +  2aq     - 
(mg,8iio)Oj4+laq  - 
(mgjSijK  +  f aq   - 

15-33 
15-33 
16-93 
15-82 

2-61 
2-41 
2-70 
2-60 

5-87 
6-35 
5-90 
6-07 

? 
? 
0. 

o. 

Table  IV.  From  the  structure  of  these  minerals,  Dana 
has  suggested  that  serpentine  may  be  micaceous  in  crys- 
tallization, like  talc  and  chlorite.*  This  is  so  far  true  that 
a  silicate  having  the  centesimal  composition  of  serpentine 
assumes  a  phyllcid  type,  as  seen  in  thermophyllite  and  in 
marmolite ;  but  it  also  takes  on  a  prismatic  fibrous  type  in 
chrysotile  and  in  picrolite,  silicates  of  unlike  density, 
already  mentioned  in  §  65,  and  is,  moreover,  found  as 
an  amorphous  colloid  species  included  in  the  next  tribe, 
that  of  the  Ophitoids,  of  which  it  may  be  regarded  as 
the  type. 


*  s 


System  of  Miueralogy,  5th  ed.,  p.  465. 


.  jflS 


A, 


'.ill    a 


u  ■■:  V 


m. 


''y. 


''its 


mSSSSSBk\ 


I     I 


832 


A  NATU'  ^Ji  SYSTEM  IN  MINERALOGY. 


[VIIL 


'* 


Trife  5.  OpJiitoids. 
§  67.  Irx  considering  this  tribe,  we  begin  by  noting 
certain  differences  in  composition  and  in  specific  gravity 
among  the  maguesian  silicates,  wnich  (besides  thermo- 
phyllite,  marmolite,  picrolite,  and  chrysotile)  have  hitherto 
been  grouped  under  the  name  of  serpentine.  A  density 
of  from  2.60  to  2.70  is  generally  assigned  to  this  silicate, 
but  bowenite,  according  to  the  analysis  of  J.  Lawrence 

Table  Y.  —  Ophitoids. 


Species. 

Formula. 

P 

D 

V 

Serpentine.    -    - 

(mg.,si4)07  +  2aq 

15-33 

2-65 

5-78 

Eetinalite.     -    - 

(mgaSiOo;  +  2Jaq 

15-00 

2-40 

6-2.5 

Deweylite.     -    - 

(mgjSislOj  +  Saq 

14-00 

2-25 

6-22 

Genthite.  -    -    - 

(nij8i3)05  +  3aq 

18-25 

2-40 

7-60 

Aphrodite.     -    - 

(mgisi2)03  +  ^aq 

15-13 

2-21 

6-84 

Cerolite.    -    -    - 

(mgisi2)03  +  ljaq 

14-11 

2-30 

6-13 

ChrysocoUa.  -    - 

(cuisi2)03  +  2aq 

17-53 

2-24 

7-82 

Spadaite.   -    -    - 

mg58i,2)o„  +  4aq 

15.04 

? 

•  a  •  • 

Eenaselaerite.     - 

(mg4siio)oi4  +  laq    15-93 

2-70 

5-90 

Sepiolite.   -    -    - 

(mgisi3)04  +  laq 

14-80 

? 

•  •  >  • 

Glauconite.    -    - 

t  •  •  • 

o  »  m  • 

•  '  •  • 

Smith  and  Brush,  is  a  nearly  pure  serpentine,  with  a 
density  of  2.69  to  2.78,  and  a  hardness  of  5.5  to  6.0.  Rt'i- 
nalite,  a  clearly  marked  ophitoid  or  amorphous  species, 
which  includes  much  of  the  serpentine  of  the  Laurentian 
limestones,  is  a  very  pure  magnesian  silicate,  distinguished 
from  ordinary  serpentine  by  its  lower  density,  and  its 
larger  proportion  of  water,  which,  from  several  analyses, 
the  writer  found  to  be  over  fifteen  hundredths.  The  spe- 
cific gravity  of  retinalite  is  2.^6  oo  2.38,  or  nearly  that 
assigned  to  the  phylloid  species  marmolite.     The  name  of 


lao- 

vto 

sity 

ate, 

jnce 


f8' 

i5 

22 

60' 
84 
13 
82 

•  •  • 

•90 


witli  a 
lO.   Be'i- 


VIII.] 


A  CLASSIFICATION  OF  3ILICATES. 


833 


serpentine  may,  perhaps,  be  retained  for  the  amorphous 
silicate  with  density  2.6  to  2.7,  which  must  be  dis- 
•  tinguished  from  retinalite,  as  well  as  from  chrysotile, 
from  picrolite,  from  thermophyllite,  and  from  marmolite. 
This  last  requires  farther  study,  as  does,  likewise,  bowe- 
nite,  which  merits  particular  notice  from  its  superior 
density  and  hardness,  and  requires  optical  examination. 

§  68.  Following  serpentine  and  retinalite  in  Table  V. 
are  deweylite  an  J.  genthite, — the  latter  a  niccoliferous 
ophitoid,  as  chrysocolla  is  a  cupric  one.  With  the  latter 
are  placed  the  bisilicates  aphrodite  and  cerolite,  which 
last  appears  to  have  the  volume  of  retinalite  and  of  dew- 
eylite. After  these  we  have  placed  spaJaito.  as  also 
rensselaerite  or  pyrallolite  (which  is,  perhaps,  a  compact 
phylloid  rather  than  an  ophitoid),  and  sepiolite.  Along- 
side of  this,  a  position  has  been  conjecturally  assigned  to 
glauconite  as  not  improbably  a  ferrous  potassic  ophitoid, 
of  which  a  large  part  of  the  iron  has  subsequently  passed 
into  the  ferric  condition.  ^See,  for  a  discussion  of  its 
composition,  pages  196-198.) 

§  69.  The  significance  of  this  tribe  of  amorphous 
hydrous  silicates  in  mineralogy  will  be  more  apparent 
when  wo  come  to  study  the  corresponding  tribes  among 
the  othcx  two  sub-orders  of  silicates,  and  among  the  non- 
silicated  oxyds.  In  each  of  these  we  find  a  group  of  com- 
pounds which,  although,  in  parallel  tribes,  occasionally 
assuming  crystalline  form,  require  for  their  crystallization 
conditions  not  always  present.  The  particular  silicate  of 
magnesia  which  constitutes  serpentine,  although  some- 
times crystallizing  in  hydrous  forms,  as  in  thermophyllite 
and  chrysotile,  appears  incapable  of  forming  an  anhydrous 
species  like  the  more  and  the  less  basic  crystalline  sili- 
cates of  the  same  base,  such  as  chrysolite  and  enstatite. 
Hence  we  often  find  the  hydrous  colloid,  serpentine,  still 
associated  with  the  one  or  the  other  of  these,  into  a  mix- 
ture of  which  it  is  resolved  when  its  dehydriitiou  and 
fusion  are  effected  by  heat. 


'  if 


834 


A   NATUKAL  SYSTEM    TN   MINERALOGY. 


[vm. 


Tribe  6.    ZeoUtoids. 

§  70.  The  sixth  tribe,  being  the  first  in  the  sub-order . 
of  the  Protopersilicates,  has  been  designated  Zeolitoid  for 
the  reason  that  it  includes,  and  is  chiefly  represented  by, 
that  large  family  of  silicates  familiarly  known  as  zeolites, 
which  have  been  aptly  described  as  hydrated  feldspars. 
These  are  double  silicates  of  a  protoxyd-base  and  alumina, 
the  atomic  ratio  between  the  two  being  1  :  3,  and  the  pro- 
toxyds  essentially  lime  and  alkalies,  occasionally  with 
baryta  and  strontia,  —  magnesia  being  for  the  most  part 
absent,  or  found  only  in  traces.  The  proportion  of  silica 
varies  from  that  of  thomsonite,  which  gives  the  ratios 
1  :  3  :  4,  to  stilbite  and  related  species,  with  1  :  3  :  12. 
The  water  is  also  subject  to  great  variations,  and  is  held 
with  different  degrees  of  force  —  some  species,  such  as 
lauraontite  and  chabazite,  parting  with  a  portion  in  dry 
air  at  ordinary  or  slightly  elevated  temperatures,  while 
others  are  much  more  stable.  The  intumescence  before 
the  blowpipe-flame,  which  is  characteristic  of  many  species 
of  this  family,  and  which  suggested  the  name  of  "  zeo- 
lite," would  seem  to  indicate  that  a  partial  melting  of 
these  takes  place  before  the  complete  expulsion  of  water, 
or,  in  other  words,  that  the  silicate  fuses  in  its  water  of 
crystallization.  The  zeolites  are  attacked  by  acids,  gener- 
ally with  pectisation,  and  are  but  little  condensed,  having 
high  values  for  V.  We  have  given,  in  the  accompanying 
table  (No.  VI.),  some  of  the  more  important  species  of 
this  large  family.  Pollucite,  from  the  analysis  of  JKam- 
melsberg,  is  a  zeolite,  in  which  two-thirds  of  the  protoxyd- 
base  is  oxyd  of  caesium. 

§  71.  In  the  same  tribe  of  Zeolitoids  we  place  several 
other  hydrous  silicates,  which  are  distinguished  from  the 
zeolites  by  presenting  different  ratios  between  the  prot- 
oxyd  and  sesquioxyd  bases.  The  species  here  called 
hamelite  was  described  by  the  writer  many  years  since 
as  a  crystalline  hydrous  silicate  of  ferrous  oxyd,  magnesia. 


a. 


ler . 
for 

by, 
tes, 
lars. 
Ana, 
pro- 
witli 
part 
silica 
ratios 
1 :  12. 
J  held 
icli  aa 
in  dry 
,,  while 
,  beiore 
species 
"  zeo- 

Iting  of 
water, 
rater  oi 

^,  gener- 
having 

[panying 
rjecies  oi 
[oi  Kara- 
Irotoxyd- 


VIII.] 


A  CLASSIFICATION   OF   SILICATES. 

Table  VI.  —  Zkolitoids. 


835 


Species. 

Formula. 

P 

D 

V 

X 

Xanthorthite.- 

( mialisia  )o4  +  2aq  -  ( 

m=< 

3e,  fe)  -    -    - 

•  •  •  • 

2.90 

•  •   • 

c. 

Hamelite.  -   - 
Catapleiite.    - 

(m,al,sis)08  +  laq-( 

,m- 

=  mg,fe,na) 

•  «  •  • 

18.09 

•  •   • 

2.80 

•  •  • 

? 

TT 

^mjZrgSitjOg  T^  zaq  - 

" 

0.40    ii..  1 

Cancrinite.     - 

(na,al,88i„)05,+  3CiCaiO,+4iaq    -    - 

.... 

2.42 

•  «  * 

II. 

Thomsonite.  - 

(mials8i4)08  +  2}aq- 

(m 

=  cainai)   - 

13.58 

2.38 

6.54 

O. 

Gismondite.  - 

(caial38i4.5o)o8.5o  +  4Jaq 

14.38 

2.26 

6.36 

o. 

NatroHte.  -    - 

(naialjSi8)Oio+2aq 

15.83 

2.25 

7.03 

0. 

Scolecite.   -    - 

(caialj8i8)o,o  +  3aq  - 

16.08 

2.40 

6.28 

c. 

Mesolite.   -    - 

(mial3Si8)Oio  +  3aq  - 

(m 

=»  cafnaj)    - 

15.15 

2.40 

6.31 

c. 

Levynite.  -    - 

(caial3ei8)o,o+4aq 

- 



14.64 

2.16 

6.77 

K. 

Pollucite.  -    - 

(mjalasig)©,,  +  laq  - 

(m 

a=  csSnaJ)    - 

21.46 

2.90 

7.40 

I. 

Analcite.   -    - 

(na,als8i8)Oij  +  2aq  - 

- 

15.71 

2.29 

6.86 

I. 

Eudnophite.  - 

(naial38i8)Oij  +  2aq 

- 

i  .71 

2.27 

6.92 

0. 

Laumontite.  - 

(caialjsig)©,,  +  4aq 

- 

14.68 

2.30 

6.38 

C. 

Herschelite.  - 

(mialsBi8)o,2  +  5aq- 

(m: 

=  na|ki)-    - 

14.76 

2.06 

7.16 

O. 

Phillipflite.     - 

(mial3si8)Oi2  +  5aq  - 

(m 

=cai|naj)    - 

14.41 

2.20 

6.55 

0. 

Chabarite.     - 

(caial3si8)oi2  +  6aq- 

- 

14.05 

2.19 

6.41 

R. 

Gmelinite. 

(mi8l38i8)oij+6aq- 

(in  = 

=  cajnaj)    - 

14.11 

2.17 

6.50 

R. 

Faujasite.  -    - 

(mial3si,)Ois-h9aq- 

(m 

=rnajcaj)  - 

13.45 

1.92 

7.00 

I. 

Hypostilbite  - 

(caial38i9)Oi3+6aq  ■ 

- 

14.10 

2.20  6.40 

? 

Harmotome.  - 

(mial38iio)Oj4+5aq 

.(m 

sasba^-nai^o) 

16.73 

2.45 

6.82 

o. 

Epistilbite.     - 

(caial38ii2)oi8  +  5aq 

- 

14.47 

2.25 

6.43 

0. 

Brewsterite.  - 

(mial38ij2)Oi6+5aq 

.  (m 

=  BrSnaJ)    - 

15.27 

2.45 

6.23 

c. 

Stilbite.      -    - 

(caial38i„)oi6+6aq 

• 

14.23 

2.20 

6.46 

0. 

Heulandite.   - 

(caial3sii2)Oi8  +  5aq 

- 

14.47 

2.20 

6.58 

c. 

Edingtonite.  - 

(baial48i7)oi2  +  4aq 

- 

17.84 

2.71 

6.58 

T. 

Sloanite.    -    - 

(caial58i7)oi3  +  3aq 

• 

15.31 

2.44 

6.27 

O. 

Forestite.  -    - 

(caial«|Bi,2)Oi9  +  6aq 

- 

14.56 

2.40 

6.06 

0. 

and  soda,  which  is  found  filling  the  pores  of  a  paleozoic 

crinoid,*  while  catapleiite  is  a  zirconic  zeolitoid,  in  which 

zirconia  takes  the  place  of  alumina.     Here  also  we  have 

*  Ampf.  Jour.  Science,  1871.  i.,  379;  see  also  ante,  p.  104,  for  details. 


336 


A  NAT  U  UAL  SYSTEM  IN  MINEIIALOGY. 


[VIII. 


placed  xanthorthite,  a  hydrous  species  which,  by  its  com- 
position and  its  low  density,  is  widely  separated  from  the 
a;  lyd-ous  dense  adamantoid  orthite,  or  allanite,  to  be 
>  >uce(l  farther  on.  While  the  species  just  noticed  are 
f  'e  protobasic  than  the  zeolites,  there  are  not  wanting 
t.:ui,  ijples  of  zeolitoid  species  less  protobasic  than  these. 
Sucii  ■  the  curious  barytic  silicate,  edingtonite,  to  which 
analysis  assigns  for  protoxyds  and  alumina  the  ratio,  1:4; 
sloanite,  zeolitic  in  habit,  with  a  ratio  of  1  :  6,  and  for- 
estite,  a  species  closely  resembling  stilbite,  to  which  is 
given  the  ratio,  1  :  6.  The  hydrous  carbosilicate,  can- 
crinite,  and  the  sulphatosilicate,  ittnerite,  which  properly 
belong  to  the  zeolitoids,  will  be  noticed  under  the  follow- 
ing tribe,  in  §§  83,  84. 

Tribe  7.   Protoperspathoida. 

§  72.  We  Tiave  next  to  consider  the  Protoperspathoids, 
which  include,  besides  the  feldspars  and  the  scapolites,  a 
number  of  other  species  of  double  silicates,  chiefly  alumi- 
nous. The  species  of  this  tribe  are  distinguished  from  the 
preceding  by  their  higher  density,  superior  hardness,  and 
greater  resistance  to  acids ;  since,  while  the  whole  of  the 
zeolites  and  zeolitoids  are  decomposed  thereby,  generally 
with  pectisation,  only  the  more  basic  of  the  protoper- 
spathoids are  thus  attacked. 

The  feldspars,  like  the  zeolites,  have  the  atomic  ratio 
between  the  protoxyds  and  alumina  represented  by  1  :  3, 
the  silica  in  both  being  subject  to  the  same  variations. 
As  in  the  zeolites,  the  protoxyd-bases  are  alkalies  and 
lime,  rarely  with  baryta,  while  magnesia  and  ferrous 
oxyd  are  but  exceptionally  present.  Unlike  the  zeolites, 
they  are  anhydrous,  or  contain  occasionally  one  or  two 
hundredths  of  water. 

§  73.  The  feldspar  family  includes,  first,  the  feldspars 
proper,  represented  by  the  anorthite-albite  genus;  sec- 
ondly, orthoclase,  microcline,  and  hyalophane,  near  which 
may  be  placed  nephelite  and  paranthite;    and,  thirdly. 


Hy 


vep 


vm.] 


i- 

36 

re 

ng 

ich 
:4; 

for- 
h.  is 
can- 

pevly 


bhoids* 
lites,  a 
alumi- 
om  til® 
ss,  and 
of  tbe 
nerally 
rotoper- 


jic  ratio 

Iby  1  •  ^' 

Itiations. 

[lies  and 
ferrous 
zeolites, 
or  two 

feldspars 
inus;  sec- 
lear  Nvliicft 
thirdly^ 


A  CLASSIFICATION   OF  SILICATES. 
Tablk  VII.  —  Protoperspatkoids. 


337 


Species. 

Formula. 

P 

D 

V 

X 

Melilite.     -    - 

(oa2m,8i3)Og-(m  =  alifiJ)    -    - 

20.46 

3.10 

6.60 

T. 

Eudialyte. 

(in4zrj8ii,)o,8  -  (m=nai.5cai.5fei.o) 

20.80 

3.00 

0.70 

R. 

Wohlerite.-    - 

• 

•   ■   t    • 

3.41 

•   •    • 

C. 

Humboldtilito. 

(oa3al2si5)oio 

I'lTO 

2.00 

0.05 

T. 

Ilvaite.  -    -    - 

(m;,fli8i3)oio  ■  (m  =  feScai)  ^ 

.     iii 

3.71 

0.15 

O. 

Gehlenite.  -    - 

';ca,.om,.o8ii.3)o3.s  -  (m  ==  al«     ^ 

.,  .,.? 

3.00 

6.48 

T. 

Sarcolite    -    - 

(ca,al,si2)04 

18.75 

2.93 

0.40     T. 

Milarita    -    - 

(in,al,8i8)Oio  -  (m  =  cao.8ko.j) 

1;-J.88 

2.59 

0.51 

0. 

Barylite.    -    - 

(bajal38i,)Oia       ...         -    - 

25.75 

4.0;^ 

6.38 

? 

Meionite.  -    - 

(ca4al98i,j)025  -   -    -    - 

17.80 

2.74 

0.49 

T. 

Wernerite.     - 

(m4al98iie)029 

17.41 

2.70 

6.44 

T. 

Ekebergite.    - 

(m4al9sii8)03, 

17.42 

2.74 

6.32 

T. 

Mizzonite. 

(uiialBsiaOosi 

17.20 

2.62 

6.56 

T. 

Dipyre.  -    -    - 

(m,al98i24)037  -    ------ 

16.89 

2.64 

6.39 

T. 

Marialite.  -    - 

(m4alaSi3e)049 

16.43 

2.  .57 

6.39 

T. 

Sodalite.    -    - 

(na,al98i,2)024cli 

19.88 

2.30 

8.28 

I. 

Nosite.  -    -    - 

(naial38i4)08  +  Jnai8i04     -    -    - 

20.28 

2.40 

8.25 

^, 

Hauyne.    -    - 

(naial38i4)08  +  ?caiSi04     -    -    - 

21.60 

2.50 

8.64 

^* 

Lapis  lazuli.  - 

•  •  •  • 

2.45 

LeiTcite.     -    - 

(kial3si8)Oia 

18.16 

2.56 

7.09 

I, 

Hyalophane.  - 

mial38i8)Oi2  -  (m  sbajkj)   -    - 

19.39 

2.80 

6.92 

C. 

Orthoclase.     - 

(kial38i,2)Oia 

17..37 

2.54 

6.83 

C. 

Microcline.     - 

(kial3sii2)Oi8 

17.37 

2.54 

6.83 

A. 

Nephelite.  -    - 

(naialjSi4.5)08.6 

17.58 

2.66 

6.00 

H. 

Paranthite.    - 

{caial38i4)08 

17.37 

2.75 

6.31 

T, 

Eucryptite.     - 

(Iiial38i4)08 

15.75 

2.67 

5.93 

H. 

Anorthite.  -    - 

(caial38i4)08 

17.37 

2.75 

6.32 

A. 

Barsowite; 

(caialasi5)09 

17.11 

2.73 

6.27 

? 

Labradorite.  - 

(mial3si8)oio  -  (m  =  cafnaj)     - 

16.97 

2.70 

6.28 

A. 

Andesita  -    - 

(inial38i8)oj3  -  (m  =  cajnaj)     - 

16.70 

2.68 

6.23 

A. 

Oligoclase. 

(inial3si9)oi3  -  (m  =  nafcaj)     - 

16.63 

2.65 

6.27 

A. 

Albite.  -   -   - 

(naial38ii2)Oig 

16.37 

2.62 

6.24 

A. 

lolite.   -    -    - 

(mial38i5)09  -  (m = mgjfej)     - 

16.81 

2.67 

6.29 

H. 

Petalite.     -    - 

(Ii,al48i2o)o25 

15.32 

2.42 

6.83 

C. 

^'  'it    '3 


if  J- 


f 


: '      1 


^rsM 


338 


A    NATURAL  SYSTEM   IN   MINEUALOGY. 


[vm. 


1 


n 


u 


leucite.  These  distinctions,  as  may  be  seen  from  the 
table  No.  VII.  correspond  to  different  values  ,of  V. 
lolite,  a  ferro-magnesian  feldspathide,  tliough  peculiar  in 
composition,  and  differing  in  crystallization  from  thp  feld- 
8i)ar8,  agrees  in  volume  with  anorthite  and  albite.  Eu- 
cryptite,  which  has  the  formula  of  a  lithia-anorthite,  seems 
to  differ  from  these  in  possessing  a  more  condensed  mole- 
cule. The  possibility  of  a  more  silicious  feldspar  than 
albite,  corresponding  to  the  supposed  krablite  of  Forch- 
hammer,  with  its  ratios  of  1  :  3  :  24,  should  not  be  over- 
looked. The  specific  gravities  of  orthoclage  and  micro- 
cline  show  for  these  species  a  considerably  greater  atomic 
volume  than  for  albite  and  its  related  species,  a  fact  which 
was  noted  in  1854  by  the  writer  as  a  reason  for  referring 
orthoclase  to  a  less  condensed  molecule  than  these  (§  30). 
Nephelite  also  shows  a  volume  near  that  of  orthoclase,  aa 
does  the  baryta-potash  feldspar,  hyalophane,  which  has 
the  same  general  atomic  formula  as  andesite ;  while  leu- 
cite, with  the  same  atomic  formula,  has  a  still  larger 
volume. 

§  74.  The  history  of  that  feldspar  genus  which  in- 
cludes the  species  anorthite  and  albite  has  been  noticed 
at  length  on  pages  294-296,  where  was  discussed  the 
view  that  the  feldspars  intermediate  in  composition  be- 
tween these  may  be  mixtures  of  two  homoeomorphous 
species.  The  notion  was  there  expressed  that  while  such 
mixtures  are,  as  was  long  since  suggested,  not  uncommon 
in  nature,  many  if  not  all  of  these  intermediate  feldspars 
are  really  definite  species.  The  careful  studies  of  the 
late  George  W.  Hawes  have  thrown  much  light  on  this 
subject,  by  showing  that  in  similar  and  apparently  identi- 
cal rocks  the  feldspathic  element  may  be  represented  by 
two  associated  feldspars  of  the  same  genu.s  —  in  one  case, 
apparently,  anorthite  and  albite ;  in  another,  labradorite 
and  andesite.  The  diabase  which  along  the  Atlantic 
border  of  North  America  is  found  irrupted  among  meso- 
zoic  strata,  from  Neva  Scotia  to  North  Carolina,  is  singu- 


VIU.J 


A  ci^sair,c.ATro«  o.  s.ucatks. 


839 


wh.oh  ..,«  bee,,  represe.t    C  1  7''."  '™""'«  fel<l»I«. 

however,  observed  tint,         ,  T''"'''' ■•'»'"<'»••    Hu     . 
Rock,  New  Have,,    r     ""». ''"•I'-^e,  as  f„„„d  J  w    .' 

-wch  the  ia,.g  ;'Li:;;:°«^-\"'oi»de«  «,.„,,  i.^: 

feltptllt'^eWnf  i^f^t,^'"^,"?  ^'^P-'^ition  of  the 
-«.  t)«t  f„  „e  Pair  T./'lbrC"  '"^  -^« 
.  "^- .  The  feldspar  from  thi-   .  "udso,,  at  Jerser 

jngredients  by  the  aid  of\    ' ,'.  r'"""'/"  ^"■•""  "'«  "".er 
.o<.,d  of         j,„  gravit/ 2,90  w^;/,  Potassio-mevou," 
ot  2  69,  clearly  divided  into  tJ„       I  "  '""''"■•  ^o'ution, 
W,er,  which  gave  by  analvl     ^'"'*"'"'''  »  '«hter  and  a 
'■on  very  nearly  of  amS;*  ^^""''ely,  u,e  eompo  i! 

regard  to  these  facts,  that  sliX        """^  "■«'««»«  with 
'ions  of  cooling  i„  a  TL  ^^      va,.,ations  in  the  condT 

'he  separation  ?f  the  ildlr'  l""^''*  ''''«™"'e    itht' 
fes,  anorthite  and  alb  eTtul^  '"''"'  "^  ">^  '"o  spe 
■ntermediate  species      He  '„^':  fT'™  "'  •"''  «'  »ore 
«qu,site  balance  of  comnnV    '     '*''  '''*■■«  'n^'ght,  "An 
he  necessary  to  orystalfee' su  h  »  '""^,'''-»"^'-™ee  Wo,dd 
par,"  and  conceives  tl      we  tve'T    7'*''  "  ^'"g"^  ^d- 
focks      ,  rarely  simple  arret"!':;""'?,  ">">'  ""•»>« 
-ent,t  as  was  previously  shoXby  FouT,.  f  T'""  '"''■ 
•  See  J.  D.  Dana  .„      ,  ^      ^""^  *»  ''eeent 

urn  lor  J8bl,  pp.  J29-134. 


;  *( 


-^ 


I:  M, 


I'   i- 


840 


A   NATURAL  SYSTEM   IN  MINEUALOOY. 


tviir. 


lavas  of  Santoriii  (ante,  page  213).  Meiinwhile  it  will 
remain  to  be  decided  for  each  individual  case,  whether  a 
feldsjpathic  material  intermediate  in  composition  between 
albite  and  anorthite  is  an  integer,  or  an  admixture  of  two 
integers,  which  may  themselves  be  either  the  extremes  of 
the  series  or  integral  hitermediate  species. 

Ment'oTi  should  here  be  made  of  petalite,  a  species  in 
many  resi)ects  closely  related  to  the  feldspars,  but  present- 
ing the  ratios  1  :  4  :  20.  As  regards  the  proportion  be- 
tween protoxyds  and  alumina,  it  is  important  as  the  one 
spathoid  which  corresponds  v/itli  the  rare  and  less  proto- 
basic  zeolitoids ;  while  if  krablite  be  rejected,  petalite  is 
the  most  silicious  species  known.  Its  atomic  volume  is 
identical  with  that  of  anorthite,  albite,  and  iolite. 

§  75.  The  scapolites  apparently  constitute  a  single 
genus  of  silicates  which,  approaching  in  composition,  hard- 
ness, and  density  the  feldspars,  were,  from  an  early  time, 
compared  with  them,  so  that  when,  in  1854,  the  writer 
attempted  to  generalize  the  notion  of  Von  Waltershausen 
as  to  crystalline  intermixtures  in  the  intermediate  feld- 
spars, he  extended,  as  already  shown  (§  31),  a  similar  view 
to  the  scapolites.  The  ratio  between  the  protoxyds  and 
alumina  in  the  scapolites  has,  until  recently,  generally 
been  regarded  as  1  :  2,  and  the  writer,  in  1863,  in  farther 
discussing  the  relations  of  the  scapolites,  described  them 
as  a  group  of  which  the  extreme  terms  were  meionite,  with 
the  ratios  1:2:4,  and  dipyre,  with  1:2:6;  including 
intermediate  species  which  might  be  regarded  as  crystal- 
line admixtures  of  the  two  isomorphous  silicates. 

Very  recently,  however,  Tschermak  has  reviewed  the 
scapolites,*  and  has  reached  the  conclusion  that  the  atomic 
ratio  of  the  protoxyds  to  alumina  therein  is  not  1  :  2,  as 
hitherto  supposed,  but  4  :  9,  or  1  :  2\.  In  other  words, 
if  we  would  compare  them  with  the  feldspars  by  multiply- 
ing their  atomic  formulas  so  as  to  get  in  each  the  same 
amount  of  silica,  while  anorthite  becomes  (ca3al98ii2)024, 

*  Monatshefto  fiir  Chemie,  December,  1883. 


seii 


1,1^1 


VIl!.] 


A   CLASSIFICATIOX  OF  BtLlCATEH. 


841 

»'"">  of  ca,o,.     liu'l      f    '     ■■",■"  "  »"  "*''""■'  ..f  a 
*enn  of  ".e  ^ene.'r    '      '  J  j,"  '  "-  .""•■e  t,,„  „t,.:'; 
lli>».i..  acco,-,l„ncf  with  Xr  "''"""  ^^polito. 

^  =  2  .■  9,  „,,  muUiplvill  ,.„  '"  '^^'""».'-  """"i"".  would  be 
"'X^'  into  accorc/anoe  ,v  'tT  '''^.*"  '"""'6  "'«  fo" 
9  =  36.    lieverting  to  til'  ' '',''''""»1< »  conclusion,  4- 

d.£ferfromanorthite,„„  L  '  °'/''-'!°'''  "*<"■■■  ,erie, 
°'"'  tlm-d  of  an  a  to"'!  d  ioC"°',"'  ""■"■■'""ng  each 
(o».al,„,)o„  +  i,„,„,„„^,       "^'°"»'   'i  ,''™"'V'l.    being 

«8  by  three,  to  com,,are    v  ■H^^h^^■  +  ^'l""-    *'"'"My 
ov  nnnonite,  ,ve  have  for  th    L   '!,  '',"'""""  «''™"  "l"'"' 

num.  deseribod  by  Von,  KaU,'  '"  '""""'"o  "^  fi»- 

^MoHne,l":hr::;tp'Ts  rr  --  -  - 

">;mall  quantities  in  meio'nUeT;  ""?  ■^'  ""'"'■  *^"""<1 
?;48  per  eent,  though  an  .„.,'",'"'""'"«' <»""nples 
The  theoretica  chlorifLt  '  i^.  "''''""  "'  """-'"lite 

■"g  to  Tschermak.  a  mt  °  L  r""?'.'*?  '"' '""'""-  accord- 
«uia,  one  atom  of  oxygr,! '','"?','' '""'  "'«  »'«'ve  for- 
cent),  or,  in  other  worfs  L  7Tt  ^^  '^'""""^  (^-20  per         ' 
the  additional  basic  elem™t  hi    '  ,<^'""''»'*''")"..  +  Jna/cl„ 
^yd-     In  the  sca„on  erTs  i^;;'^  ?',?  "'''™''  "«to»<    o  . 

the  series,  there  a  .pears  a  ml       ^"^'^"P"'''  "'  "lending 
^hich  gradually  rlE  ".P™?"^^'™  '"crease  in  alkalies 
".arialite  ,ve  fild  cotfeaWe   od  """!  '"  '"^^"""o  » 
general  decrease  in  dens   ^  fe  at  th;"    '°""  P"'"^'''    ^ 
but  more  accurate  determiLatio",   '„^\r';  """^  "P'^rent, 
fo>: the  scapolites.    VVe  have  T  t.       "  *"=''"'  "<>  needed 
83T,  revised  the  atomic  o™,"      '  ""'""^'"S  t'^'*-  pago 
the  ratio  of  4 :  9  for  prott^^^  '!a  .d^t  '"■  "'^^P™"  -W' 

The  tntermediate  sennolftes  of  H  """"■'• 
«e.'.es  are  imagined  by  I'ohe^ak  t    be'Tr""""'''^'"* 

^^'  ^""^^  as  proposed 


ft. 


>:'-^Mm«^i^7t&ifr-:^'^''^fSi'3m 


342 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VIIL 


by  Von  Waltershausen  and  myself,  crystalline  intermix- 
tures, but  binary  combinations,  in  different  proportions,  of 
the  two  silicates,  meionite  and  marialite.  He  notes,  (1) 
compounds  holding  one  equivalent  of  marialite  to  two  of 
meionite,  which  are  almost  or  completely  soluble  in  acids ; 
(2)  compounds  with  one  of  meionite  to  two  of  marialite, 
—  incompletely  soluble ;  and  (3)  compounds  with  less 
than  the  latter  proportion  of  marialite,  —  insoluble  in 
acids.  This  variation  in  solubility  will,  in  the  chemist's 
eyes,  be,  as  already  shown  (§  32),  a  reason  for  rejecting 
the  notion  that  they  are  admixtures,  while  he  will  at  the 
same  time  repudiate  the  attempt  to  perpetuate  in  their 
formulas  the  dualistic  notions  of  a  former  day.  These 
intermediate  scapolites,  like  the  feldspars,  labradorite,  and 
oligoclase,  and  the  various  zeolites  between  thomsonite 
and  stilbite,  must  be  regarded  as  distinct  species. 

§  77.  In  close  relation  to  the  scapolites  comes  a  remark- 
able group  comprising  sodalite,  nosite,  and  hauyne.  Soda- 
lite  has  the  atomic  formula  of  a  cblorinated  soda-meionite, 
being  (na4al9sii2)o2icli.  Nosite  is  a  similar  species,  in 
which  the  chlo  iie  is  replaced  by  oxysulphion,  while 
hauyne  is  another  species,  in  which  the  proportion  of 
protoxyd-base  is  greater  than  in  these,  giving  the  ratio 
5 :  9 :  12.  The  relations  of  these  various  species  to  an- 
orthite  and  to  each  other,  may,  if  anorthite  be  writ- 
ten (ca3al9sii2)o24.,  be  represented  as  follows:  meionite, 
(ca3al9sii9)o24  -f-  caiOi  ;  sodalite,  (nai,al9sii2)o24  -j-  najcli  ; 
nosite,  (na3al9sii2)o24  +  naiSi04;  hauyne,  (na3al9sii2)o24  + 
2(caiSi04).  Both  of  these  sulphatic  species  -contain  also 
small  amounts  of  chlorine.  Ittnerite  is  a  hydrous  species 
related  to  these,  but  containing  a  smaller  proportion  of 
sulj>hates  than  either,  and,  like  the  associated  scolopsite, 
requires  farther  study.  Lapis-lazuli,  a  sulphatic  and  sul- 
phuretted species.  '  3  composition  of  which  is  not  accu- 
rately determineu,  is  apparently  related  to  the  sodalite 
group.  Notwithstanding  the  resemblance  in  composition 
between  these  silicates  :ind  the  scapolites,  they  differ  very 


!• 


Vill.J 


A  CLASSIFICATION  OP  SILICATES. 


*J»  Wte,  „.  .„aeea  tin  L^wS™  itJrJ 

elude  under  the  general  nami  \°1'""'3"'<',  which  we  in- 
-^  to  understand^Te  .aturfofl      ^'"'■''"'^  ^""P.  '>Z 
to  nephelite.    This  latter  spterwhfh  T'  ''^  ''""■- 
volume  near  that  of  orthoZe    s  a  tn       '  ""  '"°™'' 
than  anorthite,  and  its  atominfl  "  """'"  «''<=ioi« 

".ay  be  multiplied  by  six, taUnJ  •  '""  "•  f"''-<^'^-^''->)'>,.,, 
more  simply  its  relatioi   to  "?„    P'.!'^''««'^')o=„  to  show 

»hich  was  formerly  im™„,*^;X"  %  '""^  '"''"^"J. 
donate  of  lime  wi'th  a  hydtted  n  T  ,'!''""«"'^  "f  carl 
rece«t  studies  to  be  an  hftel,    "?:''''  "PP'^"^  &»» 

*.th  the  sulphatosilieat  s  LTdthl    ,°?     ■*•  "°"P^™'"<' 

^odahte  and  soapolito  grou™     Th  ""°™^"i'=''tes  of  the 

.    *'th  a  speeific  gravity  of  245  Jl'  ""f  "'"'^  <>*  Miask, 

«p.esented  by  (na.al  Ji^xfro"'  """'f  ^^  "-r  RaulF,  is 

while  the  canerinito  o"  Dtoo  to!o  '1  """'^  +''^'"1  (°  =  6). 

-  portion  of  potash,  and  XkZt^  *"  ^och,  contains 

f  r  *"™"'''  '»  the  amounte  of  r  ™"'',"'™  '™'°  «>« 
hydrous  carbosilicate,  life  ?he  h  i"™  ""^  ^'"«'-  This 
ntnerite,  will  fi„d  «  ilace    ''„  ^  'T  ^'P^atosilicate 

we\Ive  thrrcmarkaUe°  b"mio'^"^  ?"''"^'"'^'<=  ^P^^oids, 

-g.the  anomaly  of  a  hig2  L'' '"?  ''"'•^"''>  P™»ent 

''""ug  the  ratios  2:3:7   Z^T  "'^T'  *W<^''.  "'hile 

spars  and  scapolites,  is  said  tn        !  ™'''™<'  "^  the  feld- 

M'larite,  sarcolite,  and  g  hie,  if''  *'^  """"^  "^  -oids. 

f  o«p  in  which,  the  rJoZ     .LJTT  ""  '"^^^ting 

1  ■■  1,  there  is  a  great  variation    ,r^''  *°  "'"""""  b^'ng 

fr""'  1  =  1:8,  i..  milarite  toT-     .'J' •  f  ™P"«»  "^  -"oa! 

•'•-'"' sarcolite,  aiuU  :  1 . 


'Hi.*! 


Wl  Hi 


il 


''^"***^'"'''?ii'?ri"-"r'Trr 


344 


A  NATUHAL  SYSTEM  IN  MINERALOGY. 


[Vlll. 


1^  in  gehlenite.  In  the  native  gehlenite  a  small  portion 
of  alumina  appears  to  be  replaced  by  ferric  oxyd,  but  the 
artificial  gehlenite  from  furnace-slags,  analyzed  by  Percy, 
is  without  iron,  and  is  an  oxysulphid,  containing  1.50  per 
cent  of  sulphur.  Melilite,  a  spathoid  silicate,  is  also  found 
as  a  furnace-product,  and,  according  to  Percy,  contains  a 
variable  amount  of  sulphur,  equal  in  one  case  to  1.62  per 
cent,  while  the  native  melilite  is  destitute  of  sulphur. 
Under  this  name  are,  perhaps,  confounded  two  distinct 
species.  The  luUficial  melilite,  whicli  approaches  the  so- 
called  humboidtilite  in  composition,  has  an  atomic  for- 
mula near  to  (ca3al2si5)0j  ,  and  a  volume  almost  identical 
with  gehlenite,  while  the  rative  melilite  is  more  nearly 
(caoalisig)©^.  Similar  atf>mic  ratios  to  the  last,  as  regards 
the  bnecs,  are  presented  b;  eudialyte,  a  zirconic  spathoid, 
the  composition  of  which  is  nearly  represented  by 
(m^zr2sii2)oi8,  and  which  contains  much  lime  and  soda, 
with  a  little  chlorine.  The  atomic  formula  of  wohlerite, 
another  zirconic  spathoid,  containing  some  niobic  acid 
replacing  silica,  also  with  lime  and  soda,  is  not  well  estab- 
lished. In  these  two  species  we  have  examples  of  the  com- 
plete replacement  of  alumina  by  zirconia.  In  melilite  as 
analyzed  by  Damour,  and  also  in  gehlenite,  a  partial  re- 
placement of  alumina  by  ferric  oxyd  is  shown,  and  a  com- 
plete substitution  of  this  kind  appears  in  ilvaite,  a  spathoid 
species  having  a  density  of  3.71.  The  higher  specific 
gravity  of  4.00,  observed  for  some  examples  of  ilvaite, 
may  show  a  related  species,  or  more  probably,  as  suggested 
by  Dana,  may  be  due  to  an  admixture  of  gothite  or  other 
iron-oxyd.  Of  the  species  included  in  this  tribe,  wohlerite, 
is  a  niobosilicate,  eudialyte,  the  scapolites,  and  sodalite 
are  silicates  more  or  less  chlorinated,  nosite  and  hauyne 
are  sulphatosilicates,  while  lapis  lazuli  is  also  sulphuretted. 

Tribe  8.   Protuperadamantoids. 
§  80.    We   come  next  to   the   Protoperadamantoids,  a 
very  important  tribe.     Beginning  with  the  most  highly 


»t 


/liV 


VJII. 


Species 


A  CLASSIFICATION  OF  SILICATES. 


345 


D 


J'itrgusite 


Ke/lbauite. 
I  Schorlomite. 
jldocrase.   - 
I  Garnet. 
JAllanite.    - 
l^giiite.     - 
I  Beryl.    -    . 
j  Euelase.     - 
jArfvedsonite, 
JArdennite. 
jAxinite.     - 
jEpidote.    - 
jZoisite.  -    - 
I  Jadeite.     - 
I  Gastaldite. 
I  Glaiicophane 
I  Prehnite.    - 
I  Acmite. 
I  Spodumene. 
I  Sapphirine. 
I  Staurolite. 
I  Coronite.    - 
ISchorlite,  - 
Aphrizite.  - 
I  Indicolite. 
JRubellite.  - 


(oaaaljsi5)ojo  -    ■ 
(caialisijo^   -    . 

(°iiaI,si,)o,.(m=ceJca^fej) 

(m3fisi,)o,,.(na,==„a,ca,fe.) 
(bo3al3si,,)oj3     .... 

(be,al3siJog  +  laq  .    .    _ 
(inn^alasOog  +  iaq     ... 

(^•axm,si3)o,+Jaq  .  K=.alffif ) 
(c%aIjsi3)oe  ...... 

(na,aI,si,)oa 

(mialosiojog 

(nisalasiajois     -    .    .    _    _ 
(c32al3sifl)o„  +  laq  .    . 

Kfi.«i.)o,.(m,  =  na,.,fe,;) 
("-a],siio)o,5 

(mg,a],si,)os 

(feial,siV5)o,.5  +  ^aq  -    -    . 
(m,al3si5)09 

(miaI,ai6)o„ 

(m,al68i8)o,5 

(mial„si,2)o,3 

(m,ali2si,5)oj8 


).63      ? 

'.67     T. 


i.53 


3.10; 
3  20  I  5, 

'  y.08 : 5, 

'  .'3.00  I  0 


i.90     O. 
t.92     O. 
*-3«     R. 
'.38  I  R. 
-38  j  R. 
■33     R. 
.35     R. 


l^ole,  connecting  tl,e  piotonp,«!i     !        ^^""""^us  amphi. 


iriiBiii 


m 


■"  ('■ 


cf  >  1 


mi  ^" 


346 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VIII, 


silicate,  which,  like  titanite,  is  attacked  by  chlorhydric  acid, 
a  character  not  coiumon  to  many  adainantoids,  except  the 
more  highly  basic  species  of  the  first  sub-order,  and 
already  noticed  (§  57).  In  keiHiauite,  one-third  of  the 
alumina  is  replaced  by  ferric  oxyd,  and  in  the  titaniferous 
schorlomite,  which  is  also  attacked  by  the  acid,  and  has  a 
ratio  very  near  to  keilhauite,  the  whole  of  the  sesquioxyd 
base  is  ferric,  while  a  partial  replacement  of  the  same 
kind  is  observed  in  some  varieties  of  idocrase.  Next  in 
order  comes  garnet,  including  many  species,  in  some  of 
which  ferric  or  chromic  oxyd  replaces,  more  or  less  com- 
pletely, alumina ;  while  the  protoxyd-base  is  either  wholly 
lime,  or  in  part  magnesia  or  manganous  or  ferrous  oxyd. 
The  single  example  of  garnet  give".  \n  table  A'^III.  i.-;  that 
of  a  pure  lime-alumina  species  oxarii'uod  by  the  writer. 

We  have  placed  allanite  near  to  garnet,  for  the  reason 
that,  according  to  Rammelsberg,  the  best  determinations 
give  approximately  the  garnet-ratio,  1:1:2,  rather  than 
that  of  epidote,  1:2:3,  not vvitl 'standing  that  the  species 
is  homoeomorphous  with  epidote,  a!)d  is  often  spoken  of 
as  a  cerium-epidote,  to  the  atomic  ratios  of  which  some 
analyses  f;i;:"ircntly  conform.  A  farther  study  of  the 
group  *  [  mi'  ,rals  commonly  included  under  the  name  of 
allanite  or  orthite  is  required.  The  great  differences  in 
density;  the  facts  that  some  resist  the  action  of  acids, 
while  others  are  attacked  thereby ;  that  some  are  anhy- 
drous, while  others  are  more  or  less  highly  hydrated,  —  all 
lead  to  the  conclusion  that  several  species  are  here  in- 
cluded. We  have  already  separated  therefrom  the  so- 
called  xanthorthite,  as  a  cerium-zeolitoid,  and  it  is  probable 
that  besides  one  or  two  hydrous  species,  and  a  true  ada- 
mantoid,  there  will  be  found  at  least  one  intermediate 
spathoid  species.  The  alumina  in  th3  allanites  is  often 
in  part  replaced  by  ferric  oxyd.  A  pure  alumina-allanite, 
with  the  garnet-ratio,  in  which  the  protoxyd-bases  are 
equally  divided  between  cerous  and  ferrous  oxyds  and 
lime,  gives  the  value  for  V  as  here  calculated.     Of  the 


;,l 


»• 


VIII.] 


A  CLASSIFICATION"  OP  SILICATES. 


347 


illi 


species  in  the  table,  keilhauite  and  schorlomite  are  titano- 
silicatas,  ardennite,  a  vanadosilicate  or  arseuosilicate,  and 
axinite,  a  borosilicate,  while  both  boric  oxyd  and  fluorine 
enter  into  the  composition  of  the  tourmalines. 

§  81.  The  glucinic  species,  beryl,  is  generally  regarded 
as  having  the  atomic  ratio  1:1:4,  and  has  a  volume 
near  to  garnet.  The  late  analyses  of  Penfield*  have, 
however,  shown  that  beryl  contains  a  small  and  variable 
amount  of  alkalies,  replacing  glucina,  besides  a  portion  of 
water  varying  from  1.50  to  2.50  per  cent.  He  finds  that 
the  composition  of  the  mineial  is  best  expressed  by  the 
more  '^ implex  formula  (gl5al6si22)0334-4aq,  a  change  which, 
however,  affects  very  slightly  the  values  calculated  in  the 
table,  that  of  Y  being  thereby  changed  to  5.48. 

Euclase,  though  closely  related  to  beryl  in  composition, 
and,  like  it,  liydrated,  shows  a  much  greater  condensation. 
Ardennite,  which  presents  the  atomic  ratio  of  euria?;. ,  and 
is  also  hydrated,  is  essentially  a  manganese-alivnuna  sili- 
cate, with  some  magnesia  and  lime,  besides  a  small  portion 
of  vanadate,  more  or  less  completely  replaced,  in  s  ;me 
instances,  by  arsenate.  These  latter  elements  are  prdba- 
bly  comparable,  in  their  relations,  to  the  sulplirtes  m 
nosite  and  hauyne.  Abstracting  them,  we  find  f  tlie 
silicate  essentially  the  formula  given  in  the  table,  which 
can,  however,  only  be  regarded  as  ajf  "oximate.  Preh{;ltc.; 
although  classed  by  Shepard  in  tl  order  Zeolite,  be- 
longs to  the  present  tribe.  It  has  i  .;  ratios  2:3:6,  which 
are  those  of  euclase  and  ardennite,  and  like  those,  and 
epidote,  is  hydrated,  while  its  voluuie  is  near  to  those  of 
beryl  and  idocrase. 

The  species  axinite  is  notict  u.e  for  containing  some 
boric  oxyd.  The  formula  which  we  have  deduced  in  the 
table,  in  which  one  eighth  of  the  silica  is  thus  replaced, 
and  one  third  of  the  sesquioxyd  is  ferric,  is,  also,  but  an 
approximation.  The  composition  of  this,  like  that  of 
beryl,  of  ardennite,  and  a  great  number  of  polysilicates, 

*  Amer.  Jour.  Science,  188^    \xviii. ,  25. 


ift.  i 


jrs:SSSiiii:^ii..,.^fiMth3ta»ii  ak,^ 


348 


A   NATURAL   SYSTEM   IN   MlNKllALOGY. 


[VIII. 


Jll 


cannot  be  accurately  represented  by  such  simple  formulas, 
which,  however,  suffice  to  show,  with  sufficient  exactness, 
the  atomic  volume  and  the  place  of  the  species  in  the 
system. 

§  82.  We  come  next  to  epidote,  the  composition  of 
which  presents  many  variations,  due  in  part  to  a  greater 
or  less  replacement  of  alumina  by  ferric  oxyd,  and,  in  the 
so-called  piedmontite,  by  manganese  sesquioxyd.  The 
presence  of  a  small  amount  of  water,  equal  to  about  2.0 
per  cent,  seems,  as  in  beryl,  euclase,  and  ardennite,  to  be 
essential  to  the  composition  of  the  species.  The  atomic 
formula  for  a  pure  lime-alumina  epidote,  as  imagined  by 
Ilammelsberg,  is  (caial2si3)0(; ;  but  such  an  epidote  is 
unknown  in  nature,  and  we  have,  for  the  purpose  of 
determining  the  A'olume  of  the  species,  selected  a  variety 
in  which  one  third  of  the  sesquioxyd  is  ferric.  The  for- 
mula, morei  ver,  takes  no  note  of  the  small  amount  of 
water  present  in  the  species. 

Zoisite  is  essentially  a  lime-alumina  silicate,  seldom  con- 
taining over  five  or  six  hundredths  of  ferric  oxyd,  and 
often  traces  only.  It  is  not  improbable  that  the  true 
ratio  of  the  protoxyd  and  sesquioxyd  bases  in  these  two 
species,  as  in  meionite,  with  which  they  have  been  paral- 
jcled,  may  be  represented  by  4  :  9,  rather  than  by  1  :  2. 
We  note  next  the  more  silicious  jadeite,  whose  formula, 
as  already  pointed  out  (§  81),  is  related  to  that  of  zoisite 
as  tliat  of  dipyre  is  to  meionite.  While  zoisite  is  essen- 
tiiilly  a  calcic  species,  seldom  containing  over  three  or 
four  hundredths  of  soda,  iadeite  is  sodic,  and  it  appears, 
like  the  comi^act  zovAte  or  saussurite,  to  be  anhydrous. 
The  atomic  volume  of  jadeite,  as  shown  in  the  table, 
apj)ears  to  be  less  than  those  of  garnet,  epidote,  and 
zoisite,  showing  a  more  condensed  molecule.  Gastaldite 
has  the  atomic  formula  of  jadeite  (mial2si6)09,  but,  with  a 
dejisity  3.044,  gives  a  volume  of  5.61. 

§  83.  We  lia-^^e  next  to  notice  three  remarkable 
adamantoids,    closely   related   to    those   just   mentioned. 


\     J 


li- 
as, 

!8S, 

the 

.  of 
ater 
the 
The 
t2.0 
to  be 
toinic 
id  by 
:>te  is 
ose  of 
variety 
he  for- 
unt  of 

am  con- 
yd,  and 
[lie  true 
ese  two 
n  paral- 

y  ^  ••  2- 

iformula, 
i  zoisite 
is  esseiv 
three  or 
appears, 
hydrous, 
e   table, 
ote,   and 
astaldite 
t,  with  a 

hmarl?:able 
fientioued, 


VIII.] 


A  CLASSIFICATION  OF   SILICATES. 


349 


and  alfio  to  the  spathoid,  ilvaite.  In  garnet,  axinite, 
epidote,  and  keilhauite,  the  sesquioxyd  nuiy  be  in  large 
part  ferric,  and  in  schorlomite  and  ilvaite  it  is  entirely  sd, 
the  protoxyd-bases  in  these  being  cliietly  lime,  magnesia, 
and  ferrous  oxyd.  We  have  in  tegirite,  arfvedsonite,  and 
acmite,  three  well  defined  protopersilicates  in  which  the 
sesquioxyd  is  entirely  ferric  and  the  protoxyd  in  large 
part  sodic.  These  three  species,  which  have  hitherto 
been  little  understood,  will  be  seen  from  the  table  to  be 
related,  respectively,  regirite  to  garnet,  acmite  to  epidote, 
and  arfvedsonite  to  euclase,  and  to  have  a  common 
value  for  V  very  near  to  that  oi"  garnet  and  epidote. 

The  presence  in  each  of  these  ferric  species  of  large 
amounts  of  soda,  equal  to  ten  or  twelve  hundredths,  is  the 
more  remarkable  since  the  aluminous  silicates  with  which 
we  have  compared  them  contain  little  or  no  alkali.  This 
association  recalls  the  highly  alkaliferous  character  of  an- 
other iron-silicate,  glauconite.  While  these  three  homoeo- 
morphous  species,  all  ferric  bisilicates  with  soda,  having 
very  different  ratios  between  protoxyds  and  sesquioxyds, 
are,  from  their  condensed  molecules  and  their  indifference 
to  acids,  assigned  a  place  among  adamantoids,  the  related 
species,  ilvaite,  with  a  larger  volume,  has  been  placed 
among  the  spathoids.  It  is  possible,  from  the  analysis  of 
Rammelsberg,  that  babingtonite  may  be  a  ferric  species 
belonging  to  the  one  or  other  of  these  tribes,  but  without 
farther  analyses  it  would  be  premature  to  fix  its  place. 

§  8-4.  We  come  next  to  spodumene,  a  lithia-alumina 
species  with  the  atomic  ratio  1 :  4  :  10,  remarkable  for  its 
great  condensation  and  its  volume  of  4.88.  It  is  instruc- 
tive to  compare  it  with  the  still  more  silicious  lithia- 
alumina  silicate,  petalite,  which,  with  its  lower  density,  has 
a  volume  of  6.33,  and  takes  its  place  among  the  spathoids. 
The  relations  between  these  two  silicates  are  analogous  to 
those  between  zoisite  or  jadeite  and  a  scapolite  like  raari- 
alite.  While  these  two  lithia-bearing  species,  with  the 
ratio   of  protoxyd    to    alumina  of  1:4,  are    among   the 


350 


A   NATURAL   SYSTEM  IN   MINERALOGY. 


IVIII. 


most  silicious  known,  sapphirine,  which  has  the  same 
ratio,  is  the  most  basic,  and,  with  its  atomic  formuhi  of 
(mgial4sii)ou,  serves  to  connect  the  silicates  with  the  spin- 
ellicls,  while,  by  its  great  condensation,  it  takes  a  place  by 
the  side  of  spodumene. 

Staurolite  is  essentially  an  aluminous  double  silicate, 
with  the  ratios  of  1  :  4  :  2|,  the  protoxyds  being  ferrous 
oxyd  with  a  little  magnesia  and,  rarely,  a  portion  of  oxyd 
of  zinc.  In  one  variety  it  would  seem  that  manganese- 
sesquioxyd  replaces  a  portion  of  alumina,  and  a  small 
portion  of  water  appears  to  be  an  essential  element. 
Omitting  the  water,  we  get  a  volume  of  6.01. 

§  85.  We  come  now  to  the  tourmalines,  a  family  of 
silicates  which,  perhaps,  might  be  called  a  sub-tribe,  ^ince 
the  five  distinct  species,  representing  as  many  genera, 
differ  from  each  other  not  only  as  the  related  silicates, 
albite,  labradorite,  and  anorthite,  or  as  zoisite  and  jadeite, 
but  also,  at  the  same  time,  as  anorthite  differs  from  meio- 
nite,  or  as  lime-garnet  from  idocrase  or  epidote.  In  other 
words,  not  only  the  relations  of  the  protoxyds  to  the  ses- 
quioxyds,  but  the  relations  of  both  of  these  to  the  silica, 
are  subject  to  notable  variations  in  species  of  tourmaline 
which  so  closely  resemble  each  other  that  it  is  difficult,  if 
not  impossible,  to  discinguish  them  by  physical  characters 
alone.  The  studies  of  Rammelsberg,  which  first  clearly 
showed  the  varying  composition  of  the  tourmalines,  ena- 
bled him  to  divide  them  into  five  species,  each  of  which  is 
the  type  of  a  genus,  distinguished  by  the  ratios  of  pro- 
toxyd  to  sesquioxyd.  We  follow  him  in  regarding  the 
boric  oxyd,  which  is  fiot  constant  h\  amount,  as  replacing 
silica,  and  recognize  the  fact  that  the  tourmalines  are 
oxyfluorids  containing  a  small  and  variable  amount  of 
fluorine. 

For  the  brown  magnesia-tourmaline,  the  most  highly 
protobasic  species,  with  the  atomic  ratios  of  1  :  3  :  5,  a 
trivial  name  was  needed,  and  we  have  ventured  to  suggest 
that  of  "  coronite,"  from  Crown  Point,  in  New  Yo.rk,  a 


■iJso 
for  tl 
^e  ad 

ieast 
new  s| 

fJuced 
sniall 


VIII.] 


^    "'^    SILICATES. 


Of  "Xi  " t r ,;";'^,  o"-  "pec  r""t"  "■"" 

f  ;."clico,ite  "  Ct,:ti^™- '""""aline/ ^  TT 
V5  iioni  coninouiirI«  h..   •  ^^  ^^e  pass    in  fu- 

amount  of  altnK  P^otoxvd-basps    ih^    ""^uiui- 

ratio  of  the  sesni,;^^    i     "^  '  "^^^'a-betirino-      Thn     * 

»f  bono  oxyd,  is,  moreover  nnf.         "'"'  ™'T"'?  amount 

»neraical  variables  to  be  tilt.,,  ■ '.  ^™  "'«  ""is  maiiv 
of  a  group  of  .mnerals^S  frf  T"""'  ">  «=e  Xdy 
to'nal  cbaraoters,  were  Irevt       "  *'""''  ^^Uarity  i„  ex 

S  86.   We  have  given  i„  t,^  ^  differences  in  color 
also  in  table  No  Vm    I         ^^  Preceding  |,aram-.,r      j 

^"^p-SoiiS^fti^^-r™-^^^^^^^^^^^^^ 

'°"'  •■""^'  '^""  '<>«  exce/trs^^j.tTit;;' 


;■; 


352 


A  NATUKAL   SYSTEM   IN   MINEllALOGY. 


IVIII. 


l:\l 


TTn 


Hi  el 


^      I 


ii'! 


ferriferous  aphrizite,  which  is  3.20,  range  from  3.10  to 
3.04.*  These  figures  are  adopted  in  the  table,  save  that 
for  rubellite  the  density  has  been  placed  at  3.00.  The 
equivalent  volumes,  as  calculated  by  llammelsberg  from 
his  own  arbitrary  formulas  for  these  five  species,  respec- 
tively, gave  him  the  discordant  and  apparently  incommen- 
surable numbers,  144.6,  167.3,  241.0,  117.0,  and  148.0, 
whicli  fail  to  show  any  relations  between  the  species  com- 
pared. 

These,  however,  from  their  close  resemblance  in  external 
characters,  on  the  one  hand,  and  their  chemical  differences, 
on  the  other ;  from  their  varying  relations  between  prot- 
oxyds,  sesquioxyds,  and  silica ;  from  the  partial  replace- 
ment of  silica  by  boric  oxyd,  and  of  alumina  by  fei  Ic 
and  manganic  oxyds,  are  peculiarly  fitted  to  test  the 
correctness  of  the  new  method  of  study ;  and  this  the 
careful  determinations  of  Rammelsberg  enable  us  to  apply 
to  the  tourmalines  with  guaranties  for  accuracy  not  often 
to  be  met  with.  The  results  of  such  a  study  of  these  five 
species,  as  set  ^wn  in  the  table  above,  may  here  be  stated 
at  greater  length.  In  calculating  the  mean  weight  (P) 
of  the  oxyd-unit  for  each  species  of  tourmaline,  care  has 
been  taken  to  get  the  nearest  approximation  to  the  results 
of  Kammelsberg's  analyses  of  that  species.  The  manganic 
oxyd  in  indicolite  and  rubellite  is  included  with  ferr.c 
oxyd,  and  the  various  protobases  always  present  are 
grouped  under  the  heads  of  ferrous  oxyd,  magnesia,  soda, 
and  lithia.  The  formulas  thus  arrived  at,  with  their  frac- 
tional coefficients,  and  the  value  of  the  oxyd-unit,  got  by 
dividing  the  calculated  equivalents  by  the  number  of  units 
in  eacli  formula,  are  subjoined.  But  these  formulas  do 
not  take  into  account  the  fact  that  all  of  these  tourma- 
lines contain  from  1.5  to  2.5  of  fluorine,  replacing  a  por- 

*  For  the  original  memoir  of  Kammelsberg,  see  Pogg.  Ann.,  1850, 
Ixxx.,  449;  and  for  a  summary  of  his  results,  Amer,  Jour.  Science,  xi., 
257;  also  a  farther  discussion  thereof  by  the  present  writer,  ibid.,  xvi., 
211.  For  later  studies  of  the  tourmalines  by  Kammclsberg,  see  Annal. 
Phys.  Chem.,  1870,  cxxxix.,  ;37'.»  and  547. 


VHI.J 


A  oi,ass,k,ca™k  or  sa,c..x.«. 


S.  CL  'P.   a  o 


5-  ? 


£^  o"   S"   o    3 

i  &  a  a  s. 

?  is-  p  !r  jr 


tion  of  oxygen,  tl,e  mean  of  .1- 

1-90   of  «uori;  "'■  '■"'"^"''te 

0.17  and  0  18?'  u"   '"''""""   "« 

».;'- wit„ont";    ,""-/'"■■ 

values   arp   i.i..^   i  ^iiese 

t'.-es,  wl  ,e'  i  rl,™'  '■;  "— ■ 
fof  Uiis  mean  n    '^""f'*''  values 

ployed  for  J  '  ?  '  "'"'  "'""o  "m- 

volumeo/tt^t!  "^"""'*°'>»« 
values  of  V  !l,  °w '"'"^"-  The 
species  a  rl„,    Zl  >      ''"''  «^« 

rectness   of    ih^       -        °  ^"^  cor- 

"■e    aeeurar„"«,^^'';  "■"•*» 
«««^  of  Ra„f„elL"g.  "''"""»"■ 

P^UoIdJpUtrm''''/"'''!'-- 

""the  p/noi;r«:^:r;«''-  of 

endeavored   to  set  forth  7„    T 

accounts  of  r,i.„„.j-  "    ""> 

allows  ffrmt  r°<"^'"S  tribes.    It 

wi,  gieat  variations  in  tl,. 
'"t'ons  of   protoxyds    to''"" 

^Worites/t^h^'lirror.",? 
Muscovites    in  ,  1  •  1  ^  •  ^'  to 

Ferric  and  cln-omic  oxyds  l\'    ^^    I    «  «  S  §§  «    ,    ^   , 

species,  replace,  moreTt         "'^     ^-^~^-^d_ 

-  less  co.pieteI,,  alumina,  and  t ^ 


■>. 


IMAGE  EVALUATION 
TEST  TARGET  (MT-S) 


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Sciences 

Corporation 


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23  WEST  MAIN  STREET 

WEBSTER,  N.Y.  14580 

(716)  •72-4503 


'""^  ""' 


354 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VIII. 


Table  IX.  —  Pkotoperphylloids. 


' 


Species. 

FOBMULA. 

P 

D 

V 

X 

Astrophyllite.     - 

in  m  SI    ^rt     B»--.Mv>v 

. . . 

3.32 

•  •  • 

0. 

l™5"*2«"ioPn  --------- 

Phlogopite.     -    - 

(m,al28i8)0ij-(m4=mg3.jko.j)    -    - 

18.12 

2.85 

6.35 

0. 

Pyrosclerite.  -    - 

(mg^aljSiaKa  +  3aq 

15.40 

2.74 

5.62 

0. 

Penninite.      -    - 

(mg,.oal,.osi<.5)o,o.5  4-3aq   -    -    -    - 

15.40 

2.67 

5.70 

R. 

Ilipidolite.      -    - 

(mg5al38ie)Oi4  +  4aq 

15.38 

2.70 

5.70 

C. 

Prochlorite.    -    - 

(m4al3si<.„)0ii.j8  +  3aq  -  (m.^mg^fej) 

17.72 

2.96 

5.98 

H. 

Leu(!htenbergit«. 

(mg4.5al3.(^i5.o)Oij.5  +  3Jaq-    -    -    - 

15.46 

2.65 

5.8;-) 

H. 

Venerito.   -    -    - 

(m4m3sie)oi3  +  4aq 

16.84 

? 

CorundophUite.  - 

(m^al^siOoij  +  Sjaq  -  (m4=  rnggfe,) 

15.20 

2.90 

5.21 

C. 

Biotite.  -    -    -    - 

(m4m4sie)Oia-(m4  =  mg3.5ko.5)    -    - 

18.18 

3.00 

6.06 

H. 

Voigtite.     -    -    - 

(m4m4sig)oi8+  4aq  -  (1114  =  mgjfe,)  - 

16.48 

2.91 

5.66 

? 

Cryophyllite. 

(m3al48ii4)02i-(m3=nfe,kilii)     -    - 

17.90 

2.91 

6.15 

0. 

Seybertite.     -    - 

(maal9Si5)02o + Jaq  -  (mg  =  mg4ca2)  - 

17.97 

3.15 

5.70 

0. 

Thuringite.     -    - 

(fe8m8sig)024  +  6aq  -  {m^  =  algflj)     - 

19.56 

3.19 

6.13 

? 

Jeflerisite.  -    -    - 

(rnggwigsijojo  +  7iaq  -  (m  =  alBfi, )  - 

14.92 

2.30 

6.50 

0. 

Annite.  -    -    -    - 

(mgWiuSiisKg  -(m6  =  fe4ks)  -    -    - 

20.84 

3.17 

6.57 

? 

Willcoxite.     -    - 

(m6di28iio)o28+ 2aq  -  (mg  =  mgjna,  i 

16.76 

? 

Chloritoid.      -    - 

(feial38i2)og  +  laq 

18.00 

3.55 

5.07 

C. 

Lopidomelane.    - 

(m,m38'4)0g 

3.00 

H. 

Zinnwaldite.  -    - 

(mial38i8)oio-(m  =  ko.5lio.5)  -    -    - 

17.20 

3.00 

5.73 

0. 

Oellacherite.  -    - 

(mialjSi6)Oio  +Iaq  -  (m  =kibain)g^) 

17.33 

2.99 

5.79 

? 

Lepidolite.      -    - 

(mi.oal4.88i8.o)Oi3.5  -  (m  =  Kbh-i)    • 

16.85 

3.00 

5.61 

0. 

Margarite.      -    - 

(caialai8i4)Oii  +  laq 

16.58 

2.99 

5,54 

0. 

Euphyllita.     -    - 

(m,al8Si8)o,8-(m  =  ko.s3nao.6.)    -    - 

17.07 

3.00 

5.6!) 

0 

* 

Cookeite.   -    -    - 

(miali,8i8)o2o  +5Jaq  -  (m^lio-Tsko-js) 

14.80 

2.70 

5.48 

? 

Muscovite.     -    - 

(kialgsig)©,, 

17.75 

3.12 

5.68 

0. 

Muscovite.     -    - 

(kialgSigK  +  2aq 

16.77 

2.85 

5.88 

0. 

Muscovite.     -    - 

(kialgsiuloa 

17.27 

0. 

Damourite.    -    - 

(kial98ii2)022  +  2aq 

16.68 

2.79 

5.94 

0. 

Muscovite.      -    - 

(ko>5al8.o8l9.o)Oi5.5    ------- 

16.80 

... 

... 

0. 

Muscovite.     -    - 

(ko.5alg.9Si,.o)o,5.5  +  2aq      -    -    -    - 

15.91 

2.75 

5.78 

0. 

vm.j 


A  CLASSIFICATION  OF  SILICATES. 


355 


Protobases  vary  from  «n.  •       • 

P-sent   to  otVTn  S^^^  f  ^^^  ^^^^^-  only  are 
P  aces  being  partially  oT^tllfsuZ-  ?k  ""^^"^^'  ^^e- 
cupric  oxyd,  magnesia  hZTn/^^'^^  ^^  ^^^^^us  oxyd 
«f  -lica  to  the  base?;    res\vTder"^  '"'^^^-     ^^^   '«^^o 
same  proportions  of  protoxvd  '^^^^^       '^'''''  ^^^^^g  the 
"moreover,  species  hfvW^f,  ^"^  sesquioxyd  bases  ;  and 
compositionrand  siX  L^^^J   *^^   -me   ehe'm    af 
presence  or  the  absence  of  t"S^     TT'^  ^^^^  ^^  the 
condensation,  as  shown  byTh.      ,       ?"^'  *^^  degree  of 
er^hly  among  ph^lloil!  I    f  V£  ^^  ^'  -"-  -nsid 
well  marked  in  th^^r  physical    A        ''  "^^^^'^heless,  so 
n^icaeeous  or  phylbid  typf  fine  7^^?         '"^'^    he 
by  the  student.  ^^    '^  """^  «^  the  first  recognized 

§  88.   We  have  sookpn  nf      • 
*sti„ctio„  is  an  arbtoLVL"""  T^^orites,  but  the 
hydrous  magnesian  imZiZ'  '■"""  ^^  "^^""n  from 
"tes,  is  not  so  great  as  't  at  frri?'"°S°P"«^.  '«  ohio 

Th^^i  *«  ""-^"ovitie  type  oH  '^^  ?»«  »>icas  to 
-llie  difficulties  of  arf»n.,.;  >    ^:    "  *''einseives  Jjvdrat.,) 

-e  increased   hy  ZZTit7''Z'"«  ""^  S'-'tfbe 

PWogopite,  biotite,  and  musofvit  T^  ^P^^^"  "ame 
"ni.ke  compounds,  which  houU  T' '"^'"''^  "'•^">-^% 
The  rauscovites   present  ,„  °™  ""^t'lct  specie, 

f'fering  Hke  theCmlnri  t^™"'™'^  ■"»"?"-* 
the  micas  included  under  the  „  *''^"'/'<>">ie  ratios,  and 
variations  in  the  ratio  of  ^X?/,  ^^  P^logopite  ^how 
^•lto8:2;  while  there  aret-  ?  '° ''""l'»<"'yds  from 
f  d  1 : 2.  More  highly  L,l'"''  ^"""  ^  =  1  to  1  l" 
however,  astrophylmf  l^^'^T  "''"'  ""^  Phlogopite'  h 

2  ferric  and  zirconie  oxvd?  «       i^^  "'"■"'""  and  in  part         ' 
the  specimens  from  CoSd, '     T*"^  '»  «»"'•  whileTn 
I  present  in  traces  ont    with  K^!?"  ''y  ^oenig  alumin"  ■ 

formn  a,  1 :  j ,  2,  we  ma/note  tt  mf  f  "^'''"^  *e  atom"; 

^•^=^---»--^hitrrr:ft:;--a 


356 


A  NATURAL  SYSTEM   IN   MINERALOGY. 


[VIII. 


quioxyds,  come  the  highly  silicious  fluoric  lithia-mica, 
cryophyllite,  3  :  4  :  14,  and  die  basic  seybertite  and  will- 
coxite.  The  ratio  of  protoxyds  and  sesquioxyds  in  the 
latter,  1 :  2,  is  that  of  some  biotites,  and  of  the  ferric  spe- 
cies, annite,  near  to  which  is  the  still  more  ferriferous 
lepidomelane,  apparently  1:3:4.  A  like  ratio  appears  in 
the  dense  basic  chloritoid,  1:3:2,  and  the  more  silicic  zinn- 
waldite,  1:3:6,  followed  by  the  barytic  species,  oellacher- 
ite,  1:4:6.  In  biotite  and  voigtite  one  fourth,  in  annite, 
thuringite,  and  jefferisite  one  third  of  the  sesquioxyd  is  ferric. 

After  lepidolite,  probably  1 :  4|^ :  8,  and,  like  zinnwaldite, 
a  highly  fluoriferous  mica,  remarkable  for  containing  lithia 
with  caesium  and  rubidium,  we  come  to  the  muscovites 
proper,  with  which  the  last  two  species  are  connected  by 
the  fact  that  their  protoxyd-bases  are  alkalies  only.  The 
variations  noted  in  the  ratio  of  these  to  the  sesquioxyds 
(in  which  ferric  oxyd  replaces  a  small  portion  of  alumina) 
are  from  1 :  6  to  1 :  9  and  1 :  12,  and  the  ratio  of  the  sum 
of  these  to  the  silica  in  different  analyses  is  from  1 :  1|  to 
1 :  1^.  From  various  muscovites  have  been  deduced  the 
atomic  ratios,  1 :  6  :  9,  1 :  9  :  12,  and  1 :  12 :  18,  with  others 
intermediate,  and  a  careful  study  would  probably  show,  as 
in  the  case  of  the  tourmalines,  the  existence  of  a  series  of 
muscovites.  Near  the  muscovite  with  the  ratio  first 
named  must  be  placed  the  less  silicious  and  somewhat 
calcareous  species,  margarite,  1:6:4,  and  farther  on, 
euphyllite,  1:8:9,  and  cookeite,  1 :  10 :  9.  Of  the  phyl- 
loids,  phlogopite  and  cryophyllite  contain  more  or  less 
fluorine.  In  calculating  the  value  of  P  for  both  biotite 
and  voigtite,  W4  =  algfi^. 

§  89.  It  will  be  noted  that  in  this  list  we  have  included 
both  hydrous  and  anhydrous  species,  between  which  it  is 
impossible  to  draw  a  line  of  demar'Vj,tion.  Phlogopites 
and  biotites  are  reputed  anhydrous,  but,  as  is  well  known, 
contain  in  many  cases  from  two  to  four  hundredths  of 
water,  while  corundophilite,  willcoxite,  seybertite,  chlori- 
toid, oellacherite,  margarite,  euphyllite,  and  cookeite  are 


vin.j 


867 


all  more  or  less  hydrous  •  th„  ' 

«x  hundredths  i„  euphvliVl  '  "?'""'*  »'  water  risi„e  t„ 
oooteite  A„,„  ^^  •'^  "'"' "id  to  twien  tK.f  "'"8  to 
,  ™-  Among  inuscovitp«  :„  ,.,"^  '«»«  amount  in 
f°"nd  .n  all  proportions  "1;,  '*\  banner,  water  i" 
damourite  and  pa'ragonite  7bill  Tsf  '^t""^  ^P'--  «' 

t  f     •'""'  ^""la-rausoovite     Th.  "^  "'^  described  as 

:^ater„,phy„„id,„^j;*^    The  pre^^^      „^  ^^^_^     d  as 

tt  classihcation  among  nhvl^J  ^'°'""' "^  a  distinction 
»antoids,  where  we  6nd  ber  °  Iv'T  "'"^  ^an  in  ada 
»>te,p,eh„ite,epidote"a„d  m2  ^'''  ^^'•^''  ^"lase,  arden 
en  ers  as  an  essential  'ZeT"''''' '"  ""  »'  -hioi  water 

Tn^^'^^ZS^^"^--  the  Ohio- 
to  the  phlogopites  and  the  b;  ff       '™^'  "eariy  related 

IrtT'^  V"^"'"-  PWogopt  ttth  ?"''  ~-^to 
apart  from  the  water,  of  4.  o   «   '"*.tl>e  atomic  ratios 

mous  species,  represented  by  4   27/""}!  '^  *  '-'  ^ 
the  closely  related  ripidolii   '.   '  t*"    ^*'<"'  *I>ese  come 

and  prochlorite.     Cron  S    ttth  Ti" '"^'*^'  «"-"«! 

able  as  an  example  of  a  well  Tfi!' .  ^T"^  «  ■•e-nark- 
nt.c  species  very  near  tolchtorl  '"''  ""■^^•^"'"^  ^ll 
eonta.„.ng  a  large  proportfon  ofXpe"  ?"^t"'  ">»' 
•  Thi,  apecie,,  „i|„i  "PP*"^-      CorimdophUite 

from  six  to  seven  nir  ^P""  ^'•"'  ^^  ^^ich  severaUho.?     .^  ^'*^"^°  ^een 

schists  of  the  reS"  th  ''"  ""'''  ^'^  ^o^ncl  ?„  the  Sn  ■'''  '"^"'^  «»d 
eral  in  question  r^wu""-^*""^  ^^^^^l  slates  ofJ*^^"'^"  crystalline 
eral  feetVth  Ttrata  :  "^"ted  ^°  S'-^-ter  o  t^s  abtS.r''  V  *^«  '°'°- 
Poor  in  copner  f'!**' *^™ating  with  layers  of  »  Z^^*'^^^  through  sev- 
with  the  S;i  '  ""^'^  '"^'•^«d  ^ith  feSL.'TT*""^^'-«^aterial 
an  inch  or  xnoretTv.   T  '""'^^'^^ted  with  velTn       "'^^  ^'"^^  ^°'ncide 

g'-ams  of  quartz  and  a  small 


358 


A  NATURAL   SYSTEM  IN  MINERALOGY. 


[VUI. 


follows,  with  4:4:4,  and  the  more  silicious  species,  voig- 
tite,  4:4:8,  a  hydrous   biotite.     From  this  we   pass  to 

portion  of  magnetite.  A  qualitative  examination  of  this  material  showed 
that  it  contains  no  carbonates,  and  is  not  of  the  nature  of  a  clay,  but  con- 
sists of  a  hydrous  silicate  of  magnesia,  copper-oxyd,  alumina,  and  iron- 
oxyd,  constituting  a  kind  of  copper-chlorite.  It  is  but  feebly  attacked  by 
dilute  acids,  while  strong  acids,  and  notably  sulphuric  acid  diluted  with 
two  or  three  parts  of  water,  and  aided  by  a  gentle  heat,  readily  and  com- 
pletely decompose  it,  with  separation  of  flocculent  silica,  which,  by  solu- 
tion in  dilute  soda-lye,  is  readily  separated  from  the  accompanying  quartz 
and  magnetite.  A  single  somewhat  rough  analysis  made  in  this  way 
gave  me,  for  100  parts:  insoluble  sand,  14.10;  silica,  24.60;  alumina, 
13.00;  magnesia,  15.15;  ferric  oxyd,  7.11;  cupric  oxyd,  15.30;  water,  11.50. 
=100.70.  The  qualitative  examination  of  a  considerable  portion  of  an- 
other and  less  pure  specimen,  gave  an  appreciable  quantity  of  zinc,  and  a 
distinct  trace  of  nickel.  A  portion  of  the  specimen  of  this  copper-silicate 
of  which  the  analysis  is  given  above,  was  freed  by  careful  washing  alike 
from  the  coarser  grains  and  from  the  lighter  portion,  which  remained 
long  suspended  in  water.  The  material  thus  purified  was  somewhat 
richer  in  copper  than  before,  and  has  been  carefully  analyzed  by  my 
friend,  Mr. George  W.  Hawes,  of  New  Haven,  who  found:  insoluble  sand, 
6.22;  silica,  28.93;  alumina,  13.81;  ferric  oxyd,  5.04;  ferrous  oxyd,  0.27; 
magnesia,  17.47;  cupric  oxyd,  16.55;  water,  12.08=100.37.  This,  deduct- 
ing the  insoluble  matter,  gives,  for  100  parts:  silica,  30.73;  alumina,  14.67; 
ferric  oxyd,  5.35;  ferrous  oxyd,  0.29;  magnesia,  18.55;  cupric  oxyd,  17.58; 
water,  12.83=100.00.  This,  as  remarked  by  Mr.  Hawes,  gives,  on  calcula- 
tion, an  oxygen-ratio  between  protoxyds,  sesquioxyds,  silica,  and  water,  of 
4:3:6:4,  very  nearly,  which  puts  this  mineral,  if  it  be  a  homogeneous 
substance  (as  its  microscopic  characters  would  indicate),  among  the  chlo- 
rites,  some  of  which  it  resembles  very  closely  in  its  atomic  ratios.  Before 
the  blowpipe,  on  charcoal,  it  swells,  then  fuses  quietly  into  a  black  globule, 
giving  the  usual  reactions  for  copper.  The  iron  is  almost  wholly  in  the 
state  of  sesquioxyd,  as  shown  by  two  determinations  of  the  amount  of 
protoxyd  of  iron,  which  gave,  respectively,  0.27  and  0.29  per  cent.  This 
copper-chlorite  appears,  alike  from  its  physical  and  chemical  characters,  to 
constitute  a  distinct  mineral  species,  for  which  I  propose  the  name  of 
Venebite,  in  allusion  to  the  mythological  and  alchemistic  name  of 
copper."  ( "  A  New  Ore  of  Copper  and  its  Metallurgy." )  Trans.  Amer. 
Inst.  Mining  Engineers,  iv.,  325. 

The  atomic  formula  for  venerite  given  in  the  table  above  represents  it 
as  a  chlorite  in  which  a  part  of  the  sesquioxyd  is  ferric  and  a  part  of  the 
protoxyd  is  cupric.  This  formula  (mg».r6CUi.26al3.6ofio.6osi6.oo)oi3.oo+4aq, 
requires:  silica,  31.4;  alumina,  14.8;  ferric  oxyd,  4.6;  magnesia,  19.2; 
cupric  oxyd,  17.4;  water,  12.6=100.00,  which  agrees  very  closely  with  the 
numbers  deduced  by  Hawes  from  his  analysis,  and  varies  but  little  from 
my  own  analysis,  given  above,  of  a  less  pure  specimen,  when  calculated 
for  100.00  parts.    A  microscopic  examination  of  this  curious  chlorite  will 


VIII.] 


A  CLASSmcATION  OP  SILICATES. 


359 


-»e  ratb  „f  piVx^d  'sf'"'  ^P^''-  having  the 
»«<!  as  the  more  bJolZiTT'"?'^'  "^  «mriLt7 
4 '  6 :  8i.    Foilowi,,rthe  "        ^^  ^  ""''ylrous  seybert  te 
^Wcoxite,  ohIoritoW,   „e  1 '  r"/"^  ''^"'■"''^  "Peoie  ,  are 
and  damourite.    We  have  t  /  f '    "'"garite,  cookeite 
P>-otoperphylI„id  triL    frl"  17'-  '''.^-'gh-'ut  the  whole 
auhydrous  and  a  hydm'jT-  ^'''''g^P"''  *«  musoovite   an 
""de  up  of  the  Xe  h; ',  r  "1'!"'^  '^•"<>»«o  group  i" 
»«-.    In  these  eomparS  ^^  -"  """"'«'«''*  '»« 
tie  atomic  ratios  from  th    formal   ™  ^"'™™"y  ''^d-oed 
tern  of  Mineralogy,"  whli  ^"''"  "'  Sana's  "Svs 

"ud.es  of  Rammelsberg^hen  1      ,""""■"*»  <"'-'»'i»al 
throw  much  Usht  on  thJ         ■   P'^°P^'^^y  interpreted  will 

|-eaters»ph|ty::hett:;r,'t^^^^^  '''  ">'—    ^- 

X  have  been  omitted  in  diseussTnaTi^       "T ™" '°  Table 

§  91.  Related  to  the  chlor    "sTut^.T''.'"^ '''™'''''^- 

toe.  IS  the  epichiorite  of  Ram„t\      """^  '"  ^'™«- 

fibrous    or   columnar    and    ^''"""^'^erg,  described  as 

4.;3--9:4,whioheo™sp'nVt:T^  *^,.'"°"'°   -«ot 
"te.    In  this  connection  mav  be  '"'"■V^"'™»«  Prochlo- 

nndescribed  mineral  wh^hfefouml  """*""""'  *  '^"'erto 
«'e  and  it«  accompanying  caAo„l    ™"t '"  *''«  ''"*''™- 
n-onth,  Rhode  Island.    TWs  sltn      .'  ""'"'^  *"  ^'''-t^-       • 
penetrating  quartz,  but  in  it"  trf  ;\'°"'«'-"es  seen 
l-^yish-green  mass,  consis  W  of 'le  !  f  'PP'""^  '««  a 
fibres,  resembling chrv-oHU  „        •      .'  ''"nsverse,  flexible 
been  confounded  Tnor  .  "^  ."""""thus,  with  which  it  has      • 

ef  an  inch  wide  gave  me  h!""  ^"  '  ^''''  "'""■*  "»  eight! 
21-80 :  ferrous  S;n6W    mr=^"''?''^-««--''>»ina: 
^  '  '"'•^"'  "nagnesia,  8.96;  lime,  2  01  • 


•^     iS 


n 


It 


860 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[vni. 


potash,  2.69 ;  soda,  4.24 ;  volatile,  9.30  =  102.90.  A  sub- 
sequent microscopic  examination  of  the  material  analyzed 
showed  the  presence  theriiin  of  interspersed  films  of 
pyrites,  thereby  vitiating  to  some  extent  the  results  of  the 
analysis,  which  deserves  to  be  repeated  on  a  portion  of 
the  miner.'.l  purified  by  the  aid  of  bromine-water.  Mak- 
ing allowance  for  some  pyrites,  the  atomic  ratios  of  this 
fibrous  species  are  4:4:6:3,  being  near  to  prochlorite, 
and  to  voigtite,  which  like  it  contains  a  little  lime  and 
soda.  In  this  unnamed  amianthoid  mineral  from  Ports- 
mouth, possessing  nearly  the  composition  of  a  chlorite  or 
a  hydrous  biotite,  and  in  the  epichlorite  of  Rammelsberg, 
we  have  apparently  examples  of  a  hydrospathoid  form  of 
these  alumino-magnesian  protopersilicates. 

With  these  should  be  noted  the  pilolite  of  Heddle,  who 
has  described  under  that  name  the  substances  hitherto 
known  as  mountain  cork  and  mountain  leather,  which 
have  a  fibrous  texture,  are  more  or  less  flexible  and  tough, 
and  occur  in  veins  or  fissures  alike  in  crystalline  lime- 
stone, in  sandstones  and  shales,  and  also,  as  observed  by 
the  writer,  as- a  deposit  upon  quartz  crystals  in  granitic 
veins.  From  several  analyses  by  Heddle,  pilolite  is 
shown  to  be  a  highly  hydrated  silicate  of  alumina  and 
magnesia  with  ferrous  oxyd,  and  is  nearly  represented  by 
(mg2.6feo.6al2sii6)o2o+12aq,  a  formula  requiring:  silica  51l7; 
alumina,  7.8;  magnesia,  11.5;  ferrous  oxyd,  6.2;  water, 
24.8=100.00.  More  than  one  third  of  the  combined  water 
is  expelled  at  a  temperature  of  100°  Centigrade.* 

Tribe  10.  Pinitoids. 
§  92.  Corresponding  with  the  ophitoids  of  the  proto- 
silicates,  we  find  in  the  present  sub-order  a  tribe  of 
hydrous  silicates  which,  since  the  species  known  as  pinite 
may  be  taken  as  the  type,  we  have  called  Pinitoids. 
These  bodies  approach  in  composition  and  in  density  the 

*  Mineralogical  Magazine,  1870,  ii.,  206,  cited  in  the  Third  Appendix 
to  Dana's  Mineralogy,  p.  94. 


VIII.] 


^  OlASBmcATIOK  OP  SILICATES. 


00  urre„oeofthi,„,j,,i^,^;^a™  esewhere  noted  the 


^^^^  ^— PimroiDs. 


ot  other  species.     ?;„,>«  •  -^ — ■' 

a«d  alumina,  having"  1 1!!''^*^^"^  ^  «i««ate  of  potash 
*hus  approaching  cloTewT     "^^'''  «^  ^  •'  « •'  12 :  3  and 
;«"«eovite.     Coss^aitewhLlT^^^^"^     '^  ^  ^dCs 
^«'  'f  not  a  pinitoid,  aclmr .  ?  '  *^''  ^'•'^^^°«  of  1 :  9    12    o 
musnnvif^  „-  ,     .  '  '^  compact  narao.^,.,-^^  ..  ,      •  ^  •  i^ .  J, 


--  'f  not  a  Pinii   ra'clr  ?"  ""  ™«-  of  1    9T""/ 
than  ;.  'di:5  ••  «•  i-^  probably  r.,lT"^[''  "'  ^"h  the 


ratios,  1 .  12   Ji^T""""*.  which  resemM,  "f"    """^'^ 


862 


A  NATURAL  SYSTEM   IN  MINERALOGY. 


[VIII. 


I 


amorphous  silicates  with  varying  amounts  of  water,  and 
the  atomic  ratios,  1:3:5,  —  the  protoxyd-bases,  as  in 
joUyte,  being  chiefly  ferrous  oxyd  and  magnesia,  with  a 
little  potash.  Bravaisite,  with  the  ratios,  1:3:9:4,  and 
hygrophilite,  1:5:9:3,  are  similar  species,  the  protoxyd- 
base  of  which,  as  in  pinite,  is  chiefly  potash.  Near  to  this 
is  sordavalite,  a  similar  hydrous  species,  of  which  the  prot- 
oxyd  is  magnesia  and  the  peroxyd  is  in  part  ferric. 
With  these  pinitoids  we  have  placed  obsidian,  pitchstone, 
tachylite,  and  palagonite,  to  which  latter  the  atomic  ratios, 
1:2:4,  excluding  water,  have  been  assigned.  That  its 
composition  is  not  clearly  fixed,  or  rather  that  more  than 
one  silicate  may  have  been  included  under  this  title,  does 
not  detract  from  the  interest  which  attaches  to  this  curi- 
ous, unstable,  hydrous  colloid,  so  long  since  the  object  of 
studies  by  Bunsen,  the  importance  of  which  I  have  else- 
where pointed  out  (^ante,  page  129),  and  which  are  noted 
below,  in  §  109. 

§  93.  The  species  of  the  sub-order  of  protopersilicates 
which  approach  the  persilicates  in  composition,  resist 
chemical  agencies  more  than  those  species  which  contain 
larger  amounts  of  protoxyd-bases.  To  this  greater  stabil- 
ity is  due  the  fact  that  such  species  are  often  produced  by 
the  partial  transformation,  through  aqueous  influences,  of 
silicates  like  the  protoperspathoids.  Such  silicates,  formed 
originally  by  igneous  or  by  aqueous  action,  may  thus  con- 
tinue to  lose  protoxyd-bases,  often  with  silica,  until  a  con- 
dition of  comparative  fixity  is  rcaclied  by  the  production 
of  bodies  having  the  chemical  composition  of  pinite,  of 
the  muscovitic  micas,  and  even  of  pyrophyllite  or  of  kao- 
lin. Inasmuch  as  such  compounds  are  in  many  cases  the 
result  of  secondary  processes  like  that  just  described, 
chemists  have  been  disposed  to  assign  a  similar  origin  to 
them  wherever  found,  not  considering  that  where  the 
proper  chemical  conditions  unite,  these  compounds  may 
be  directly  formed.  That  nephelite,  for  example,  may,  as 
is  supposed,  under  favoring  circumstances,  be  transformed 


vni.j 


^  C,^«mOAT,OK  OK  »„.,e^,^. 


363 


'nto  pmite,  is  aue  to  th.    . 

r.t"-re^f;- rj':?  r/r  -«- ^^^^^^^^^^^^^^ 

^n  the  inorganic  vvorJd      JW  .^^ '""^'^''^  *'f  the /ittesf '' 
conduce  to  tho  »...    i      .'        "^  *'i««o  verv  minf  '^ 

epigenesiH    .f  /  ^'^"ction  of  such  st.I  f      ^'""'  ^"^''^'J» 

J"-'  mentioned  2       ?'""  ^""•"'  »*  W""     i    h  "'""■ 

pinite,  or  bed**  nf  »,•         .  "  other  word-^  tl.^  i    i  * 

STanftL      •  niica-sch  St,  lite  tk.    ""'^™'  tue  beds  of 

gwnitic  veins,  have  not  be-n  „    !        muscovitio  mica,  of 

SL:  s^^^r'^  of  sedi,::?,ts  d  ™:  d°?"-"™^- 

oraers  of  minerals.    Such  nhZ?^'     ^''■''ates,  as  in  other 
^flic'ed  in  fissures  and  opet  ^f  ^,,'>^™  been  especiX 

gy  of  Canada.  1863,  pp.  482-480. 


864 


A   NATURAL  SYSTEM   IN   MINKKALOGY. 


[VIII. 


W:  f 


channels  for  waters  of  changing  cuinposition  and  tempera- 
ture, during  the  long  process  which  has  filled  these  open- 
ings with  mineral  masses.  In  this  way,  crystals  deposited 
at  one  stage  are  attacked  at  another,  and  are  either  more 
or  less  completely  dissolved  or  transformed  into  insoluble 
products  which  are  now  found  surrounding  nuclei  of  the 
unchanged  mineral,  or  in  some  cases  penetrating  its  sub- 
stance. Examples  of  such  actions  are  familiar  to  all  who 
have  studied  attentively  the  history  of  granitic  and  related 
veinstones.  Care  should,  however,  always  be  taken  in 
the  study  of  pseudomorphs  to  keep  in  mind  another  and 
a  different  phenomenon,  namely,  that  resulting  from  the 
power  of  a  substance  in  the  process  of  crystallization  to 
cause  other  bodies  to  assume  its  own  geometric  form. 
Examples  of  these  are  seen  in  the  cases  of  calcite,  dolo- 
mite, and  gypsum  crystallizing  in  the  midst  of  silicious 
sand,  by  which  are  generated  such  aggregates  as  the  so- 
called  crystallized  sandstone  of  Fontainebleau,  which, 
while  having  a  crystalline  shape  belonging  to  calcite, 
includes  from  50  to  63  per  cent  of  quartz  grains.  A  not 
less  remarkable  case  is  seen  in  staurolite,  which,  according 
to  Lechartier,  retains  its  crystalline  form  and  general 
aspect  even  when  by  the  inclusion  of  foreign  matters, 
chiefly  quartz,  the  proportion  of  silica  is  raised  from  the 
normal  content  of  28.0  to  50.0,  and  even  54.0  per  cent,  cor- 
responding to  more  than  one  part  of  quartz  with  two  parts 
of  staurolite,  the  mixture  still  retaining  the  crystalline 
form  of  the  latter  species.  Thus  a  compound  in  crystal- 
lizing may  give  its  geometric  form  to  a  large  portion  of 
some  extraneous  matter,  which  it  compels,  as  it  were,  to 
assume  its  own  crystalline  shape. 


'5F 


i'i 


i' 


Tribe  13.   Peradamantoid. 

§  95.   It  may  be  noticed  that  in  the  second  sub-order 

the   less  protobasic  silicates  do  not  assume  zeolitoid  or 

spathoid  forms.     With  the  exception  of  sloanite  and  for- 

estite  (both  of  which  demand  further  study),  we  find  no 


VlII.j 


^  c^Asa,r,c.Tro»  ok  sa,0Ai.3. 


•P^O'-o^  in  those  tril      ^  ™'*  ««» 

p""toid5,  through  ;;ctf "''"'"»""'"'».  I'l^yi  w  *  r 

"^'--ted  with  thft  of  the      ""■"''  ""»  '"l^'oS  t'." 
Species.         |     rT^       '^         T 

^       '       D      /        y 


Oumortierite. 

•Andalusite.    . 

^'ibrolite.  -    . 

Topaz.   .    .    . 
Pyanita    .    . 
'  BuchoJzite.    . 
'  Xenolite.  -    . 
'  "^orthite.  -    . 
'  I-yncurite.     - 
'  Malacone.  -    .    . 
I  Zircon.  ... 

I  Auerbachite.  -    - 
I  -^thosidepite. 


(al,si,)o, 
(a^38i,)oj   . 

^*J»8J2)Oj    - 

(aiasijoj   . 
(a'3Si,)o,   . 
(^hsish,   -    , 
/a^6Sij)o„  +  iaq| 
(zri8i,)oj,   . 

KsiiK  +  laqj 
(zi"iSi,)o,   . 

^fii8>sK  +  |aq 


•  •  • . 


exceptions,  included  in  fi  ^  ~~~ 

f '•e  designated,  as  we  L?'  ^^^^^sponding  tribes     Th 

atnn.;!?!'"  respecting  it,  to  h.  fT"'  ^,^^«^er,  from  the 


details  ^  ven  "^°"^«^^'«"d,  would  seem  h  ^^^^^nite, 

^tomic^rJlVf  ^^«^i"^  it,  to  be  a  perz'eorr?::'  ^^"^"^  ^^^« 

inic  7,-rn.   •        '-^^  b^smuthic  oxv.l  i  ^  Peradaman- 


%'^'.^^J 


866 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VIII 


and  the  related  agricolite  and  bismutoferrite,  will,  from 
their  chemical  and  physical  characters,  take  a  place  in 
the  tribe  of  perspathoids.] 

§  96.  The  adamantoid  persilicates  constitute  a  charac- 
teristic and  remarkable  group.  Of  the  aluminic  species, 
we  fi'id  dumortierite,  andalusite,  fibrolite,  bucholzite,  and 
worthite,  with  differing  atomic  ratios,  and  in  one  case 
hydrous,  all  presenting  the  same  value  for  V ;  besides  the 
remarkable  oxyfluorid,  topaz,  and  the  more  highly  con- 
densed kj'^anite  and  xenolite,  the  latter  two  having  a 
smaller  atomic  volume  than  any  other  silicates  known. 
A  single  ferric  species,  anthosiderite,  appears,  and  more 
than  one  zirconic  species. 

It  is  known  that  minerals  having  the  crystalline  form 
and  the  centesimal  composition  of  zircon  present  variations 
in  density  from  4.86  to  4.02.  The  careful  studies  of  A.  H. 
Church,  in  1875,  confirmed  the  previous  statements  of 
others  as  to  the  differences  in  density  among  the  minerals 
included  under  the  name  of  zircon.  Thus  he  found  the 
hyacinth-red  crystals  from  Expailly  to  have  a  specific 
gravity  4.863,  which  was  not  changed  by  ignition.  Of  a 
large  number  of  zircons  examined  by  him.  not  less  than 
twelve  varied  from  4.60  to  4.70,  while  an  opaque  brown 
zircon  from  North  Carolina  had  a  density  of  4.54,  which 
was  changed  to  4.67  by  long  ignition,  and  a  transparent 
brown  zircon  from  Frederickvarn  had  its  density  by  the 
same  process  raised  from  4.48  to  4.G3.  Another  zircon, 
dark  green  in  color,  slightly  opalescent,  and  flawless,  had 
a  pecific  gravity  of  only  4.02,  which  was  not  changed  by 
igjiition.  It  was,  nevertheless,  according  to  Church,  a 
true  zircon,  giving  by  analysis  the  percentages  of  that 
species.*  Auerbachite,  an  isomorphous  zirconic  species, 
has,  with  different  atomic  ratios,  a  specific  gravity  of  4.05, 
and  agrees  in  volume  with  malacone,  a  hydrous  zircon, 
which  has  a  similar  density,  while  other  related  hydrous 

*  Church  oil  Densities  of  Precious  Stones,  Geological  Magazine  for 
1875. 


(• 


[Vlli 

from 
ice  in 

;harac- 
,pecie8, 
te,  and 
le  case 
des  the 
ily  con- 
iving  a 
known, 
id  more 

me  form 

ariations 
of  A.  H. 

iments  of 

,  minerals 

:ound  the 

a  specific 

on.     Of  a 
less  than 

[ue  brown 
54,  which 
ransparent 
lity  by  the 
ker  zircon, 
[wless,  had 
hanged  by 
[church,  a 
es  of  that 
lie  species, 
Lty  of  4.05, 
ms  zircon, 
d  hydrous 

Magazine  for 


VIII.] 


A  CLASSIFICATION   OF  SILICATES. 


367 


zirconic  silicateEi  give  tjpecific  gravities  of  from  4.00  to 
3.60.  It  would  appear  that  the  zirconic,  like  the  aluiiiinic 
adamantoids,  include  species  varying  alike  hi  atomic  ratio, 
in  condensation,  and  in  the  presence  and  absence  of  water. 
An  anhydrous  zircon  with  the  ratio  1  :  1,  and  a  density 
of  4.86,  has  an  atomic  volume  of  4.68 ;  and  one  of  4.70,  a 
volume  of  4.84 ;  while  a  zircon  with  the  lower  density  of 
4.02  has  a  volume  of  5.65.  This  last  we  may  distinguish 
by  the  trivial  name  of  "  lyncurite,"  from  the  lyncurion  of 
Theophrastus,*  while  the  denser  zircon  of  Expailly  will 
also,  perhaps,  require  a  distinctive  name.  [Oerstedite 
appears  to  be  a  less  silicious  zirconic  apecies  than  those 
already  named,  and  hydrous,  like  malacone.  Its  analysis 
affords  ratios  approaching  those  of  the  aluminic  species, 
dumortierite ;  but  a  small  amount  of  protoxyd-bases 
serves  to  make  its  composition  doubtful.  If  theee  make 
an  integral  part  of  the  species,  it  will  take  its  place,  with 
catapleiite,  wohlerite,  eudialyte,  and  astrophyllite  among 
Protopersilicates.] 

Tribe  14.  Perphylloid. 
§  97.  As  regards  the  phylloid  tribe  of  the  persilicates, 
an  important  chapter  of  their  history  is  connected  with 
pholerite  and  kaolinite.  It  was  in  1825  that  Guillemin 
described,  under  the  name  of  pholerite,  a  hydrous  silicate 
of  alumina,  micaceous  in  structure,  to  which  he  assigned 
the  atomic  ratio  for  alumina,  silica,  and  water  of  3  :  3  :  2. 
This  was  the  same  as  that  deduced  from  the  analyses  of 
Brongniart  and  Malaguti  for  ordinary  kaolin,  although 
Forchhammer  had  proposed  for  the  latter  the  ratios  3:4:2. 
The  uncertainty  as  to  the  composition  of  these  silicates 
which  prevailed  thirty  years  since  is  reflected  in  the  fourth 
edition  of  Dana's  "  System  of  Mineralogy,"  published  in 
1854,  where  the  first-named  ratio  was  ascribed  to  kaolin, 
with  the  remark  that  it  occasionally  presents  the  second 
ratio ;  while  of  pholcite  it  was  said  "  that  it  does  not 
*  Moore's  Ancient  Mineralogy,  p.  145. 


I 


i 


>t 


368 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VIIL 


differ  much  from  kaolin  in  composition."  Hence  it  was 
that  when,  in  the  same  year,  the  writer  found  and  ana- 
lyzed a  crystalline  micaceous  kaolin  giving  for  its  compo- 
sition, silica  45.50-46.05,  alumina  38.37,  lime  0.61,  magnesia 
0.C3,  water  13.90  =  99.56,  the  analyses  of  pholerite  and 
of  kaolin  were  discussed  by  hm,  and  the  conclusion  was 
reached  that  the  first  ratio  mentioned  might  represent  the 
^  composition  of  both  of  these  substances  when  free  from 

Table  XII.  —  Pebphylloids. 


Species. 

Formula. 

P 

D 

V 

X 

Pho:erite     .    .     . 

(al3si3)o8-f-2aq    .     .     . 

14.25 

2.51 

5.67 

0. 

Talcosite     .     .     . 

(ali,si,)o„-f-laq  .     .     . 

15.b3 

2.50 

6.13 

? 

Kaolinite     .     .    . 

(aljsi,)©; -|- 2aq    .     .     . 

14.33 

2.63 

6.44 

0. 

Pyrophyllite    .    . 

(al2si5)o,  +  faq   .     .     . 

15.00 

2.80 

5.35 

0. 

Pyrophyllite     .     . 

(al2si4)08  +  §aq    . 

15.00 

2.92 

5.13 

0. 

foreign  matters,  and  consequently  that  "  the  mineral  in  its 
pure  form  is  no  other  than  a  crystalline  kaolin."  In  1863, 
in  accordance  with  this  view,  kaolin  and  pholerite  were 
regarded  as  identical.  Of  pholerite  it  was  then  said  that 
"  it  may  be  regarded  as  that  substance  [kaolin]  in  a  crys- 
talline condition.  From  its  foliated  or  micaceous  struc- 
ture it  may  be  considered  as  a  hydrated  Uxica."*  It  should 
here  be  added  that  the  writer  had  in  1855  an  opportunity 
of  comparing  the  crystalline  mineral  ^rom  Canada  with 
the  original  pholerite,  and  of  discussing  the  question  of 
the  minerak  w'th  Guillemin,  in  Paris. 

§  98.  Jo  was  not  until  1867  that  this  subject  was  again 
taken  up,  and  this  time  by  S.  W.  Johnson  and  J.  M. 
Blake,+  who  showed  that,  as  regard.^,  the   composition  of 

*  See  Hunt,  Report  of  Geological  Survey  of  Cana^'a,  1853-56,  p.  386, 
and  further,  Geology  of  Canada,  1803,  p.  495. 
t  Anier.  Jour.  Science,  xliii.,  iJol. 


hyd 
I'eta 


VIII.J 


fo™  which  ar^T"^  "^  ^''"""irafX?;'''''"''""™ 

Jislieri  ^u        '^^wiout,  however  fiii,,^-  ^  name  of 

-     se;eT'^-»*ie3ub^e""t,f  ^  ""^  »™  pub! 

wiu  serve  to  show  whv  ih^  ^"^^  ^"storieal  qItIj-  i, 

^ng  in  1854  and  ^m^\^     P'""^"*  ^"ter,  whOe  1       ^ 

§  99-   In  the  )ast!!^*  ^^^  ^'^^''^'''«- 

designated  Argiiloid     m  f  "*"  "^  "'"ys,  we  hZl 

position  assigned    o  K  .        "  "■'"^''''1  having  thl  T 

-.cnsoono,ud:fth!t4'nw,:^'"'--^^^^^ 

a^i  Kaohns,  it  i«  n^f  •         !     ^"■^^^o^d  species  anr^^o      • 

samp  f,-rv,         .  °*  ifnprobabJe  tlinf  +k  ^PPears  in 

Mrated    than    half^l '"'''°^°' »''.oonseq„ent]y!Te| 


■*i 


ir'J^ii 


870 


A  NATURAL   SYSTEM   IK    MINERALOGY. 


[VIII. 


have  noticed  in  the  other  sub-orders  the  clo';e  relations 
between  the  ophitoids  and  pinitoids  and  their  correspond- 
ing phylloids.  Beginning  with  the  most  basic  of  the  clays, 
we  have  given  in  Table  XIII.  their  atomic  formulas,  with 
the  values  of  P  and  V,  so  far  as  these  can  be  determined. 
§  100.  The  genesis  of  these  persilicates,  whether  phyl- 
loid  or  colloid,  here  demands  consideration.      The  sub- 

Table  XIII,  —  Argilloids. 


Species. 

Formula. 

P 

D 

V 

Schrotterite.  -    - 

(al48ii)05  +  5aq-    - 

12.80 

2.15 

5.95 

CoUyrite.  -    -    - 

(al38i,)o4  +  4Jaq    - 

12.53 

2.15 

5.83 

AUophane.     -    - 

(alsSijK  +  eaq-    - 

12.27 

1.89 

6.49 

Samoite.    -    -    - 

(aljBisK  +  Saq-    - 

12.81 

1.89 

6.66 

Halloysite.     -    - 

(alsSiOoj  +  Saq-    - 

13.80 

2.40 

5.75 

Kaolin.  -    -    -    - 

(aljsi  jo,  +  2aq  -    - 

14.33 

Keramite.  -    -    - 

(al28i3)05  +  2aq-    - 

13.85 

Wolchonskoite.  - 

(crjSisK+Saq-    - 

15.33 

2.30 

6.66 

MontniDrillonite. 

(alisi2)03  +  2aq  -    - 

13.00 

2.04 

6.37 

Chloropal.  -    -    - 

(fiiSijK+lJaq     - 

15.51 

2.10 

7.38 

Cimolite.    -    -    - 

(alisi3)04  +  laq-    - 

14.20 

2.30 

6.17 

Smectite.   -    -    - 

(aliSi4)o5  +  4aq-    - 

12.55 

2.10 

5.97 

aerial  decay  of  the  aluminous  spathoids,  orthoclase  and 
albite,  is  apparently  the  direct  source  of  ordinary  kaolin, 
for  which  the  ratios  of  protoxyd,  alumina,  silica,  and  water 
are  0:3:4:2.  The  derivation  of  this  from  feldspars, 
having  for  the  same  elements  the  ratios  1  :  3  :  12  :  0,  is 
due  to  the  loss  of  all  protoxyds  and  two  thirds  of  the 
silica,  and  the  hydration  of  the  residue.  The  adamantoid 
and  phylloid  aluminous  protopersilicates  are  not  generally 
subject  to  such  transformations,  although  Damour  has 
described  a  silicate  with  the  composition  of  kaolin,  de- 
rived from  the  decay  of  beryl.  It  is  important,  in  this 
connection,  to  study  farther  the  sub-aerial  decay  of  other 


obsc 
the 
yiek 
little 

§ 

neces 

do  vvi 

the  ca 

^hich 


VIII.J 


"*'  SILICATES. 


formation  t:^°;^^  regarding  th,^^^         ,    ^  '^' 

^*  sometimes  rpt;      x,  ^®  ^^cay  of  a  «.      ,       ^^^^au  in 
JfaoJin  of  ohT  y    *^^  Process  of  it?  '    '^^'^  ^^^^e  i„  it. 

"""ina,  silica   a"d  I   '  """  "^  albitlhl-/^'   <"■'  «  we 

l^uchs,  not  0  •  3    /'!?";  according  to  th^' »     ,      "-"^Jting 
""'•■'  85.0,  „,f,;  *  •  2.  but  0  ..  2  :V-  2  /- "^  ^^«  "^  ^of 
"amed  clav  mat  1      •®^-    This  distin.f      ?'"="  *«-4'  alu- 
■«  resulting  ^^^l^/^a  Jed  "teramt ""!  '^"^  '""""•'o  un- 

^  ^™«ar  JcaolSf.'  *'  '''»«««  for  wS    ""  '"  """Po- 
'        removal  with  °,    '^"''o"  of  labradorif         "'*  ^  ••  3  :  6  -ft 

™'f '^d  feldspar  ;,.°V"^*  "  *'aS™  "     "'/''^  ^■"«''- 
earlier  er,.3taC' ^'2'  '"""ttiea  0?"^  7  °^  *«"  and 
*'«=  soluble  matt.,        '  "''''  ™Portant  Z       ■  ^'"^'  'n  'he 
«'«oates,  both  of tf  •'^"°^^<'  »d  the  ri  .'  '",  '^'"''"n  to 
-       »n«derable  nar.      I?*' '"  P^^t  ages  "'T'l"'''  "'"""inons 

"«  «*emS  ™'^,^°''»i^ation  of  fe„tite  '  '"''  '^"''• 

*J"=  crystals  ott  ■/  "''^  «'»wn  bt  R     ■'^"■'''iabie  in 

«°«"a  Monflna   il'if/^d  iaoChJe  »r,*'"^  *''-t 
"'■'a  silicate,  hav  „      1^'  ""^'^t  of  ab  T"^  ^"""d  at 

"''^^'vation  the  tS  f"  """'PositL  o/t'T  ^"''''-'"- 
*''o  same  locality  ^'' '''"  "oniirmerl  ,  f  """'"'to-  This 
■y'-^Wed  hi^i^V°^''Wte,andIr;bv    '^''''•y^tolfro,, 

tie  case  of  cryste  "  ^  °""  "'"'  "''Sillowt""'  '"^  to 

^  ^- VCrated  than' „;:"  P^o^ 


•1    {I. 


m 

m 


n;?: 


■tfil 


*   B 

'"I 


if 


372 


A  NATURAL   SYSTEM  IN  MINERALOGY. 


[VIII. 


The  origin  of  the  more  and  of  the  less  aluminous  species, 
like  allophane  and  schrotterite,  on  the  one  hand,  and  like 
montmorillonite  and  cimolite,  on  the  other,  remains  to  be 
discovered.  These  seem,  for  the  most  part,  to  be,  like 
halloysite,  true  colloids,  and  their  separation  from  aqueous 
solution  is  apparent  from  the  occurrence  noted  by  Dau- 
br^e  of  an  amorphous  halloy site-like  matter  deposited  by 
the  thermal  water  of  Plombieres,  in  France,  which  is  prob- 
ably identical  with  the  saponite  of  Nickles,  a  highly 
hydrated  silicate,  more  silicious  than  halloysite,  from  the 
same  thermal  spring. 

These  aluminous  silicates,  like  other  colloids,  such  as 
opal  and  bauxite,  are  probably  capable  of  assuming  a 
soluble  modification,  and  have  all  been  deposited  from  solu- 
tions. That  such  a  dissolution  and  deposition  take  place 
on  a  large  scale  is  apparent  from  the  existence  of  the  so- 
called  indianaite.  This  name  has  been  given  to  a  material 
found  in  the  coal-measures  in  the  State  of  Indiana,  where 
it  has  been  mined  and  employed  to  a  considerable  extent 
in  the  manufacture  of  potter's  ware.  It  occurs  in  irregular 
beds,  often  several  feet  in  thickness,  beneath  a  stratum  of 
sandstone,  and  13,  associated  with  and  overlies  limonite. 
It  is  often  translucent  in  aspect,  with  a  conchoidal  frac- 
ture, and  has  all  the  aspect  of  a  colloid.  In  composition 
it  is  somewhat  more  basic  than  halloysite,  the  atomic  ratios 
of  alumina  and  silica  being  about  6  :  7,  and  may,  perhaps, 
be  regarded  as  this  species  with  an  admixture  of  allo- 
phane, translucent  masses  of  which,  in  a  pure  state,  are 
found  imbedded  therein.  Indianaite  contains  about  23.0 
hundredths  of  water,  which,  after  a  long  exposure  to  a 
temperature  of  100°  Centigrade,  is  reduced  to  14.5.*  The 
species  wolchonskoite  and  chloropal,  which  we  have 
placed  in  the  table  near  to  keramite  and  montmorillonite, 
show  that  chromic  and  ferric  silicates  present  similar  con- 
ditions to  the  silicates  of  alumina.    Hisingerite,  according 

*  Reports  of  the  Geological  Survey  of  Indiana,  1874,  p.  15,  and  1878, 
p.  154. 


VIII.j 


A   CLASSIPrOATroX   OP  sarCATES. 


to  "~'  ^^8 

S.1  cate,  at  the  end  rf  t,l  t," '''''  '^™P«=»'  ^"0  of  Per- 

classification  to  the  natm^al  s Ctl  ""/f'*'"  "'""'"^--^l 
to  show  how  the  three    ub  ni?       ■  """*  ''"™  endeavored 
onche„,ioal  and  genetic  So„tl    ,'"'"  "'""'' *''^^«  '"V, 
d.vided  into  Ave  Lbe    by  Ph*' •;'  .T'"'"''  '''  ^^^^ 
-ore  or  less  completely  in  each      ,     '';*™«=«^  repeated 
type  is  naturally  separated  f "."''/"''-"'■'ler.     The  spathoid 
hy-K'ated,  oonstUuZ"  tte  , !  ir  T-'.^  ""^highly 
rented  in  the  first  and^se  ond  of  Sr    °^   *"''«»•  ^re 
je  have  called  the  pectoltoWs  Ld  te  f'^'^f ''"'  ^^  "*"* 
decomposed  by  acids,  even  i„  tl!.     ''°'''°"J^.  both  readily 
^iieions  species.     The  ot  W  !     ^^  5  *«  ■»"«  WgWy 
smaller  portion  of    ombi    d  T!'  "''^''™"''  "'  ^"h  a 
two  hnndredths,  inclJes  th„        "''  ™'''"'»  "™^  one  or 
spathoid  tribes/in  tl:  Tatt'oT^rrlf"  "'"•  P^^er' 
spee,es  resist  the  action  rf  acidT    t?'.""™  ^"'"'o-s 
and  spathoids  in  the  first  tw\  ^1"  ''y<''-°^Pathoids 
exceptions,   which  have    been  nl^T''''   ^"■■«'  =*  fe'- 
a    larger    volume    than    tl!!  '^''^  ='S«c  i"    having 

tribes.  ">'™    «'«  species  of  the  succeedinf 

The  adamantoids  in  tl>»  tu 
are  distinguished  by  their  (.rr"  '"''-<»'^c™  of  silicates 
condensation,  and,  save  in  tb'  "■"*  *^''  »<>lccu lar 
Protadamantoids,  by  their  resLr  f  '""  """"  '^'^^ 
proportion  of  water  entei  into  S  ""''''•     ^  small       ' 

of  these  species,  not  onl^  TV!^'  «°™Position  of  many 
a«d  beiyl, and  even  in  ep  do  e  and?     "'■,^"'  "'  ^^'ase 
and  in  malacone.    It  i,  to  belted  T'".f"'' '»  '^^^'o 
Protoperadamantoids  are  not  so  ftr* !     '     "'  ""'  "'""-'"io 
apparent  ej^ception  of  garnetW  ",''™""'  Cwith  the         " 

Igneous  fusion  ;  but,  0^0^^''"*'?  ''^  "°««"g  from 
heat,  even  below  their  me  tL  °"  f^'  ''f  ">^  "ottn  of 
^O-ge.  shown  by  a  dimi^'^ZT^^Ct^^^^^^^^^^^ 


874 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VIII. 


mil 


,1,-.  'Iir-M:' 


ceptibility  to  the  action  of  acids  (§  86).  The  atomic  vol- 
ume of  the  adamantoids,  while  iii  certain  cases  not  very 
far  removed  from  that  of  spathoids,  is  ahvaj's  less,  and  in 
the  harder  or  more  gem-like  species  indicates  a  great 
degree  of  condensation.  These  characters  are  especially 
marked  in  the  peradamantoids,  which  include  the  silicates 
of  the  lowest  known  atomic  volumes. 

The  great  phylloid  or  micaceous  type  is,  like  the  ada- 
mantoid  type,  represented  in  each  sub-order,  and  ap- 
proaches it  in  condensation.  The  phylloids  in  the  second 
sub-order,  where  they  are  most  largely  developed,  include 
both  anhydrous  and  hydrated  species,  and  in  the  less  pro- 
tobasic  forms  exhibit  much  of  the  same  chemical  indiffer- 
ence to  acids,  and  to  atmospheric  action,  which  distinguishes 
the  aluminic  adamantoids.  The  species  of  all  these  tribes 
are  crystalline  ;  and  the  system  of  crystallization  to  which 
they  belong  has,  wherever  known,  been  given  in  the  pre- 
ceding tables. 

§  103.  The  colloid  forms  of  matter  which  appear  in 
each  sub-order,  and  which  we  have  designated  respectively 
ophitoids,  pinitoids,  and  argilloids,  are,  as  is  well  known, 
generated  both  by  aqueous  and  igneous  processes,  and 
hence  include,  as  might  be  expected,  both  hydrous  and 
anhydrous  species.  Those  formed  either  directly  or 
indirectly  by  the  igneous  method  are  necessarily  very 
indefinite  in  composition,  being  volcanic  glasses  or  the 
results  of  their  hydration.  The  tendency  to  chemical 
change  exhibited  by  colloids  was  insisted  on  by  Graham  ; 
and,  in  view  of  this  characteristic  (as  shown  by  Bunsen 
in  his  studies  of  palagonite,  which  is  readily  transformed 
by  heat,  in  part,  into  a  crystalline  zeolite),  the  writer  has 
elsewhere  spoken  of  this  hydrated  protopercolloid  as  a 
mineral  protoplasm  (ante,  page  188),  a  designation  equally 
applicable  to  other  colloidal  silicates.  Of  these,  serpentine 
gives  rise  to  various  crystalline  species,  often  hydrated, 
such  as  chrysotile,  marmolite,  talc,  enstatite,  and  chryso- 
lite, which  are  generated  in  its  mass  by  aqueous  action, 


r?\M 


VIIIJ 


^  -^A^Sr^ATXOK  OP  saicATKS. 


While  by  iffneonQ  f„  •       .  ™ 

solution  r     '  ''P"™'^  '""  "'e  00]  oM  """"''  ""^ 

*athU  :/eraS.:^''  "^  ""^  ^eo  ^ri:;  *"« 

taoliriite  anrl  ..       ^^^^spars,  pass  into  nhvli.- 1     ^^"^^^ous 

^Oa'u^il  t SKf  •  <"•  into  adaS;  ;    ^  ".^^ 
change  of  rprfn-        /^  cyanite,  while  ^,,^     ^^^^^^  lite 

-"^  of  the  -b.rde.Xt .S;''- 7^^--*.  -ve  to  di.„e  ^ 


It 


m 


W  i 


'i\\ 


876 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VIII. 


tribes  re-appear  in  the  nonnsilicated  oxyds,  and  serve  for 
their  classification.  Reserving  for  another  occasion  the 
details  of  classification  of  this  great  order  of  Oxydatks, 
we  may  note  that,  while  the  Oxadainantoid  tribe  embraces 
such  species  as  periclasite,  chrysoberyl,  the  spinels,  mag- 
netite, corundum,  diaspore,  hematite,  quartz,  rutile,  cas- 
siterite,  etc.,  the  Oxyspathoids  include  cuprite,  zincite» 
crednerite,  pyrolusite,  tridymite,  and  senarmontite,  and 
the  Hydroxyspathoids,  gibbsite,  gothite,  and  manganite. 
Among  the  Oxyphylloids  are  brucite,  pyrochroite,  massi- 
cot, minium,  melaconite,  hydrotalcite,  and  pyraurite ; 
while  the  OxycoUoids  or  Opaloids  embrace  bauxite,  lirao- 
nite,  opal,  uran-gummite,  and  eliasite. 

The  plan  of  the  present  essay  does  not  embrace  a  dis- 
cussion of  the  species  of  this  order  ;  but  it  will  be  advan- 
tageous, in  connection  with  the  history  of  the  silicates,  to 
notice  some  facts  regarding  the  atomic  volume  of  certain 
of  these  oxyds.  The  adamantoid  tribe  of  the  Oxydates 
includes  a  large  number  of  species  crystallizing  alike  in 
the  isometric  and  the  rhombohedral  systems,  which  give 
for  V  a  vp^ue  approximating  to  that  of  the  adamantoid 
silicates,  chrysolite,  pyroxene,  garnet,  epidote,  beiyl,  and 
tourmaline.  Ch.  Gerhardt,  in  1847,  published  a  note 
on  "The  Atomic  Volume  of  some  Oxyds  of  the  Regular 
System,"  which  was  translated  and  given  in  English  by 
the  present  writer  in  the  same  year.*  Therein  accepting 
the  view  held  by  Laurent  (§  27)  of  an  indefinite  or  un- 
limited divisibility  of  the  molecule,  Gerhardt  proposed  to 
reduce  to  a  common  formula,  MjO  (maOj  of  our  present 
notation),  not  only  protoxyds  like  periclasite  and  proto- 
peroxyds  like  the  spinels,  magnetite,  chromite,  and  frank- 
linite,  but  sesquioxyds  like  martite,  hematite,  and  braunite, 
and  titanates  like  perowskite  and  menaccanite,  including 
thus  not  only  isometric  and  rhombohedral  but  tetragonal 

*  Ann.  de  Phannacie,  1847,  xii.,  381-385,  and  Amer.  Jour.  Science, 
1847,  Iv.,  405-408;  see  a,\so  ibid.,  1852,  xiii.,  370-372,  where  the  same  sub- 
ject was  further  discussed  by  the  present  writer. 


Vlii.j 


value  of  V  ;,?'■"'»'  -ith  o„..  et,  ^  '  -'•  l"'""''.  divided 
"scribed  bvr      '  ^•^<'  *"  5.70      t         '""•S'voforthe 

conceived  tliat  t„,T    "^  various  oxvd,  ^  ^'"S  '"'" 

«  oorreetly  d 111""  f  "'^^o  ^PecioM       7"-"'  "'"'  ''« 
over,  poinded  ::'™»;,^  -<>""'  be  ti,e  t™' f"",7'"->.e. 

^"'cite  and  Sk    v'?"'  "'"'  "''"cS  „t  '?"'''"'  '<"■•  ^d 

""mpared  by  )„„'*'  »"'■■''  or  less  conder..!         .  ""'''«- 
§  loe-  Near  t  ,  "'^^  "»'« 

°.''^'<'3  thus  studied  bycT'""  *«   'he  „eat  „ 

to  titanic  oxvd  »?«    ,'5'^^'Sf'>es  V.S.K     ■^'  "'"'«  the 
orthorhombfc  h/^  ?'"'  ^°''  "'«  tetrac^onff'         """?  "«« 

Cwhich  i"'l„     '''''"S™"!  octohecMt!  v'  "  ^'"^  ^r  V  of 

""'ecnle  t  nn  T  /  ^  ^'  ^-S"-     A  stT  ,      "''^^"e'-s  to 

Vdroua  Tdatnt;:'*  "'  '•»'''  ^'-s  V'"  ,f '"^'ohedra, 
'"•ke  its  maxim?  ^a^Pore,  orthoriiomi  •  ''  '"''"«  ""= 
fo'  V,  4.2T  Tart    r™"  ^f^-flo  gt;; '"   °™.  if  we 


,t.' 


878 


A    NATUiiAL   SYHTKM    IN    MINKHALOOY, 


I VI II. 


bucholzito,  and  zircon  (V  =  4.80-4.90),  while  casHiterito 
and  (lUiirtz  are  near  to  the  spinel  ^roiip,  and  to  chrysolite, 
pyroxene,  garnet,  epi(h)te,  heryi,  and  lyncurite.  Corini- 
dnni,  dias[)ore,  and  clirysohery  1  stand  apart  from  all  of  these 
as  having  a  more  cotulensed  molecule  than  oven  cyanite 
anil  xenolite,  the  most  highly  condensed  silicates  known. 

§  107.  While  small  ditl'erences  in  atondc  volup.e  nuiy, 
Jis  (ierhardt  insisted,  he  set  down  to  impurities  and  errors 
in  determination,  a  careful  survey  of  many  silicates*  and 
oxyds  leads  to  the  conclusion  that  among  these  there  are 
great  groups  which,  essentially  agreeing  among  then:selve8 
in  molecular  condensation,  differ  in  the  value  of  V  from 
other  groups  by  (luantities  less  than  thos?  admitted  as 
accidental  variations  in  volume  in  the  large  series  lirought 
together  by  (Jerhardt;  which  may  thus  very  well  be  found 
to  include  two  or  moie  distinct  grou{)s  with  unlike  vol- 
umes. At  the  same  time,  the  comparisons  which  we  have 
here  made  among  the  adanumtoid  oxyds,  not  less  than 
those  among  the  various  tribes  of  silicates,  serve  to 
strengthen  the  conviction  that  the  accident  of  geometric 
form,  liowever  valuable  as  a  means  of  diagnosis,  is  of  alto- 
gether minor  importance  in  investigating  the  general  rela- 
tions of  mineral  species. 

§  108.  The  metals  proper,  together  with  the  bodies  of 
the  sulphur  and  the  arsenic  series,  and  the  various  binary 
and  ternary  compounds  of  all  these,  make  up  the  great 
natural  order  of  Metallates,  which  include  two  sub- 
orders. Of  these,  the  first,  or  Metallometallates,  di&tin- 
guished  by  opacity  and  metallic  lustre,  is  divided  into  six 
tribes,  which  are:  1.  Metalloids, — native  metals  and 
metal-like  elements ;  2.  Galenoids,  —  argentite,  galenite, 
bornite,  chalcocite,  metacinnabar,  onofrite,  stibnite,  etc. ; 
3.  Pyritoids, — pyrite,  linmeite,  stannite,  chalcopyrite, 
pyrrhotite,  etc. ;  4.  Smaltoids,  —  smaltite,  niccolite,  breit- 
hauptite,  with  other  arsenids,  antimonids,  etc. ;  5.  Ar- 
senopyritoids,  —  including  arsenopyrite,  cobaltite,  etc. ; 
6.    Bournonoids, — enargite,   bournonite,   zinkenite,   etc. 


"'■  "''"»n.nti„e  i„  """"'  ''l""-'i<-'»  ".ore  „r  I.        "''"""' 

Christ,,  ,^i/„    »"'^''"'''".  a,„l  i„cl,„i„  '"'■""'■'*•- ''"no- 

typ.cal  forms  snht      .f ''""""""tallates    -^^  '"''-"'•<ler 

"e  a..d  voii":  '""t  ""■"'.gh  the  ,f  ,'r'°'"\'"''  '"•'."..bar 

^vein-ht  of  fi     °"^^»ient  term  fnv  '^^""^«'  we  o-pf 

niarcasite,  vaiul  f    'S-  ""''  ^<»'  the  rv,;7-  "  ''«'".^e  the 

'  ^^  ""ogalenoids,  for 


I     -I 


'     I 


I  t  t     ' 


380 


A  NATURAL   SYSTEM  IN   MINERALOGY. 


[VIII. 


chalcocite,  7.0;  for  stibnite,  7.4;  for  galenite,  7.9;  and 
for  argentite,  8.5.  Of  the  splialeroids,  hauerite  gives  5.7  ; 
sphalerite,  6.0  ;  and  other  species,  7.0-7.4.  The  contrasts 
between  the  last  two  tribes  and  the  preceding  three,  alike 
in  their  hardness  and  in  their  condensation,  as  shown  in  the 
different  values  of  V,  are  apparent;  and  these  are  not  less 
marked  when  the  hard  and  dense  arsenopyritoids  are  com- 
pared with  the  chemically  analogous,  but  softer,  bournon- 
oids  and  proustoids.  Of  the  former  of  these,  enargite 
gives  for  V,  6.9,  and  bournonite,  zinkenite,  and  jamesonite, 
7.7-7.8;  while  of  the  proustoids,  miargyrite,  proustite, 
pyrargyrite,  and  polybasite  give  from  8.0  to  9.0,  and  du- 
frenoysite  and  tetrahedrite,  from  7.2  to  8.3.  By  reason  of 
the  variations  in  the  recorded  specific  gravities  of  most  of 
the  species  compared,  the  values  here  given  for  V  must  be 
regarded  as  but  approximations,  to  be  corrected  with  the 
help  of  more  exact  determinations. 

§  110.  The  native  compounds  of  the  haloid  elements 
may  be  included  under  the  order  Haloidate,  with  the 
four  sub-orders  of  Fluorid,  Chlorid,  Bromide  and  lodid. 
Titanates,  niobates,  tantalates,  tungstates,  molybdates, 
chromates,  vanadates,  antiraonates,  arsenates,  phosphates, 
nitrates,  sulphates,  borates,  carbonates,  and  oxalates  con- 
stitute as  many  distinct  orders.  Of  these  the  soluble 
chlorids,  sulphates,  borates,  carbonates,  etc.,  belonging  to 
the  salinoid  type,  form  tribes  under  their  respective  orders, 
as  Chlorosalinoid,  Sulphatosalinoid,  Borosalinoid,  and 
Carbosalinoid.  The  native  combustible  carbons  and  hy- 
drocarbonaceous  bodies  are  included  in  a  single  order, 
which,  from  the  fire-making  property  of  these,  may  be 
aptly  designated  as  the  order  of  Pyricaustates.  This 
is  divided  into  two  sub-orders:  1.  OarJa^es,  including  the 
phylloid,  graphite,  and  the  adamantoid,  diamond,  repre- 
senting two  tribes ;  and  2.  Carbhi/drates,  which  may  be 
convenientl}'^  grouped  in  the  four  tribes,  Naphthoid, 
Asphaltoid,  Resinoid,  and  Anthracoid. 

§  111.   It  is  impossible  to  arrange  in  a  single  line  the 


""-if'Tt'if iii'iiimiminrriii— munmiiirriri-nri  «i ,. . 


VIII.] 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


381 


)rders, 
and 
id  hy- 
order, 
lay  be 
This 
^ng  the 

repre- 
|iiay  be 

ithoid, 


line 


the 


whole  of  the  orders  of  natural  mineral  species  in  such  a 
manner  as  to  show  their  affiliations.  If,  howev^er,  we 
place  consecutively  in  a  horizontal  line  the  four  orders  of 
Metallate,  Oxydate,  Haloidate,  and  Pyricaustate,  the  sec- 
ond of  these  will  form  the  summit  of  a  vertical  column  in 
which,  beneath  the  Oxydates,  may  be  placed  successively 
all  the  other  orders :  Silicate,  Titanate,  Niobate,  Tantalate, 
Tungstate,  Molybdate,  Chromate,  Vanadate,  Antimonate, 
Arsenate,  Phosphate,  Nitrate,  Sulphate,  Borate,  Carbonate, 
and  Oxalate, —  an  arrangement  of  these  orders  of  oxydized 
compounds  in  which  general  physical  characters  have  been 
considered.  The  Metallates  are  connected  with  the  ver- 
tical column  by  sulphuretted  oxyds  like  kermesite  and 
voltzite,  and  by  sulphosilicates  like  helvitc  and  danalite ; 
while  the  sulphuretted  carbhydrates  show  the  affiliation 
of  the  Metallates  with  the  Pyricaustates.  The  Haloidates 
are  connected  with  the  same  vertical  column  by  the  oxy- 
chlorids,  by  chlorosilicates  and  fluorosilicat^?  like  sodalite, 
pyrosmalite,  tourmaline,  chondrodite,  and  topaz,  and  by 
the  haloid  elements  in  certain  arsenates,  phosphates, 
borates,  and  carbonates.  The  affiliations  between  the 
orders  in  the  vertical  column  are  seen  in  titanosilicates 
like  titanite  and  astrophyllite,  in  niobosilicates  like  wohl- 
erite,  in  sulphatosilicates  like  hauyne,  in  borosilicates  like 
datolite  and  tourmaline,  and  in  carbosilicates  like  cancri- 
nite.  Of  these  orders,  Metallates,  Pyricaustates,  and 
Haloidates  will  each  constitute  a  class,  —  all  the  remain- 
ing orders  being  included  in  another  class.* 

*  Weisbach,  tlio  successor  to  Breithaupt  at  Freiberg,  published  in  1875, 
in  bis  Synopsis  Mineralogica,  a  modification  of  the  system  of  Mohs. 
Class  I.  of  Weisbach,  Hyduolyte,  or  Salts,  includes  compounds  soluble 
in  water;  while  Class  II.,  Lithe,  or  Stones,  is  divided  into  three  orders: 
1.  Kuphoxyde;  2.  Pi/ritite  (silicate),  including  four  families :  a.  Sklerite; 
b.  Zeolite;  c.  Thyllite;  d.  Amorphite;  and  3.  Api/ritite  (non-silicate). 
Class  III.,  Metallite,  or  Ores,  is  divided  into  four  orders:  1.  Jlalo- 
vietallite;  2.  Metalloxyde;  3.  Metalle;  4.  Tliiometallc,  the  last  includ- 
ing thrbe  families:  a.  Pyrite;  6.  Galenite  (Glances);  c.  Cinnabarite 
(Blendes).  Class  IV.,  KAUSTK.or  Combustibles,  includes  five  orders: 
1.  ^me<aZ/e  (Sulphur);  2.  Anthracite  {Coals);  3.  Aaphaltite  (Vitch6a)\ 


■  I 


382 


A   NATURAL  SYSTEM   IN  MINERALOGY. 


[VIU. 


<        il 


These  four  classes  of  Metalline,  Oxydized,  Haloid,  and 
Combustible  species,  with  their  orders  and  sub-orders,  may- 
be tabulated  as  follows :  — 


Classes. 

Orders  and  Sub-orders. 

I. 

1.  Metallates:  a.  Metallometallates ;  b.  Sr>athoinetallates. 

II. 

2.  OxYDATES.  —  3.  Silicates:  a.  Protosilicates ;  h.  Proto- 
persilicates;  c.  Persilicates. — 4.  Titanates. — 5.  Nio- 
bates.  -  -•  (5.    Tantalates.  —  7.    Tungstates.  —  8. 

MOLYBDATES.— 9.  CHKOMATES.— 10.  VANADATES. — 

11.  Antimonates.  —  12.  Arsenates.  — 13.  Phos- 
phates. —  14.  NiTKATES.  —  15.  Sulphates.  —  16. 
BoBATES.  — 17.  Carbonates.  — 18.  Oxalates. 

III. 

19.  IIaloidates:  a.  Fluorids;  6.  ChlonJs;  c.  Bromjds;  d. 
lodids. 

IV. 

20.  Pyricaustates  :  a.  Carbates;  h.  Carbhydrates. 

§  112.  The  conceptions  of  high  molecular  weights  in 
mineral    chemistry,  and  of   the  existence  of    compounds 

4.  Rhetinite  (Resins);  5.  Paraffine  ("VV^xos).  The  silicates  of  heavy 
metals  are  placed  in  Class  III.,  but  with  tu?se  exceptions  the  Sklerite 
include  the  spathoids  and  adamantoids,  the  Phyllite  the  phylloids,  and 
the  Amorphite  the  colloids  of  our  three  sub-orders  of  Silicates,  arranged 
in  part  crystallographically  and  in  part  chemically.  The  Oxydates  are 
divided  between  the  Kuphoxyde  and  the  Metalloxyde,  or  those  of  the 
lighter  and  the  heavier  metals.  In  Halometallite  are  found  the  silicates 
of  yttrium,  zirconium,  thorium,  cerium,  zinc,  copper,  iron,  and  manga- 
nese, together  with  niobates,  tantalates,  tungstates,  chromates,  as  well 
as  arsenates,  phosphates,  sulphates,  carbonates,  fluorids,  and  chlorids  of 
the  heavy  metals;  the  corresponding  compounds  of  the  lighter  metals 
coming  under  the  order  Apyritite  of  Class  II.  In  a  second  edition  of  the 
Synop.sis,  in  1884,  the  Halometallite  are  made  an  order  in  a  new  class, 
called  Mctallollthe,  or  Metalstones;  while  the  order  Asphaltite  is  divided 
by  separating  from  it  the  order  Elaolte  (Petroleums).  In  the  order  of 
Thiometalle,  the  family  Pyrite  includes  alike  the  pyritoids,  smaltoids,  and 
arsenopyritoids ;  Galenite,  the  galenoids  and  bournonoids,  and  Cinnabar- 
ite,  the  sphaleroids  and  proustoids. 

From  the  point  of  view  chosen  for  our  essentially  chemical  system  it 
seems  unnatural  to  place  in  two  distinct  classes  analogous  and  closely 
I'elated  oxyds,  silicates,  carbonates,  etc.  Again,  the  different  degrees  of 
condensation,  as  shown  in  atomic  volume,  and  in  the  relations  of  this  to 
hardness  and  susceptibility  to  chemical  change,  which  underlie  the  dis- 


it'fi 


I'- 


Jji-iiii 


msmwm 

""'^r  species,  most  of  ttr  •,•'"  ^''^''^'^  Bre^h^    '''  f''^"" '«'<->',  S 


6;f   '»i'^ 


384 


A  NATURAL  SYSTEM  IN  MINEKALOGY. 


[vm. 


MJ 


h .  ill 


vs 


him,  in  his  paper  published  a  few  months  later  in  1853,  on 
the  Constitution  and  Ecjuivalent  Volume  of  Mineral  Spe- 
cies (§  17-18),  to  suppose  the  existence  of  differences 
between  the  volumes  of  isometric,  rhombohedral,  and 
various  prismatic  species.  This  notion  was,  however,  soon 
afterwards  discarded,  as  may  be  seen  from  the  citations 
from  his  paper  of  1867,  already  given  in  §  12-14. 

§  113.  In  further  illustration  of  the  supposed  relatiors 
of  density  and  equivalent,  the  following  additional  passage 
is  quoted  from  the  paper  last  cited :  — 

"There  probably  exists  between  the  true  equivalent 
weights  of  non-gaseous  species  and  their  densities,  a  rela- 
tion as  simple  as  that  between  the  equivalent  weights  of 
gaseous  species  and  their  specific  gravities.  The  gas  or 
vapor  of  a  volatile  body  constitutes  a  species  distinct  from 
that  same  body  in  its  liquid  or  solid  state,  the  chemical 
formula  of  the  latter  being  some  multiple  of  the  first ;  and 
the  liquid  and  solid  species  themselves  often  constitute 
two  distinct  species,  of  different  equivalent  weights.  In 
the  case  of  analogous  volatile  compounds,  as  the  hydro- 
oarbons  and  their  derivatives,  the  equivalent  weights  of 
the  liquid  or  solid  species  approximate  to  a  constant  quan- 
tity, so  that  the  densities  of  those  species,  in  the  case  of 
homologous  or  related  alcohols,  acioirf,  ethers,  and  glycerids, 
are  subject  to  no  great  variation.  These  non-gaseous 
species  are  generated  by  the  chemical  union  or  identii'ica- 
tion  of  a  number  of  volumes  or  equivalents  of  the  gaseous 
species,  which  number  varies  inversely  as  the  density  of 
these  species.  It  follows  from  this  that  the  equivalent 
weights  of  the  liquid  and  solid  alcohols  and  fats  mupt  be 
so  high  as  to  be  a  common  measure  [multiple]  of  the 
vapor-equivalents  of  all  the  bodies  belonging  to  these 
series.  The  empirical  formula  CimHuoOij,  which  is  the 
lowest  one  representing  the  tri-stearic  glycerid  (ordinary 
stearine),  is  probably  far  from  representing  the  true 
eijuivalent  weight  of  this  fat  In  its  liquid  or  solid  state ; 
and  if  it  should  hereafter  be  found  that  its  density  corre- 


i> 


"""''        THE  QUESTION  OF  MOLECnr  . 

MOLECULAR   WEIGHTS  QCR 

sponds  to  six  f 
§  114  In  the  papers  of  18«  !u*'"'  ™1""-  C.H,0 .." 

te7r.;;:::;ri^.^ 

those   of  fK*'^'^"  =  2500,  and  C  nrA        ^^ '"^^PeC" 

,,,?r^  "'oes  which  belong  f '  "ff'ier  (a„d  as  yet  u„! 

untouched.  These  silicates  "nd  u"""  ''""'«''  was  le  t 
^"o«.,  incapable  of  a,rcheli  r'*""-^P"^  are,so  fct 
Pos..o„s  but  such  as  IffecHr  ""'"'''"'''»"«»'■  Jecir 

";ei.-moleeu,a"v2ht:T/r"'"  "'»  S^-t  ptb^; 
whJe,  ],oweve,,  the^it'^^t"'  T"''"  »'■''""-     ^an 
favor  of  high  »olecu]afwe Xtf  ""1  ^^  '"'  '»  l^Sat 
l-y  discoveries  which  serve  f„,      ™  '"*™  strengthened 

"'  "'"  ' '"""-»  '^-Tal^Crtfr  V'  "P'^'™'^" 

■om  the  chemistry  of  tlie 


.    I] 


'  N 


386 


A  NATURAL  SYSTEM  IN  MINERALOGY. 


[VIU. 


h 


m 


carbon  series.  First  among  them  may  be  noticed  the 
various  artificial  crystallized  cobalt  comi)uiinds,  such  as 
the  potassio-cobaltous  nitrate,  to  which  wirs  assigned  a 
formula  with  2Co,  6K,  and  12N,  and  a  unit-%v^eight  of  968. 
More  remarkable  still  are  the  ammonio-cobalt  bases,  stud- 
ied by  Fr<jmy  and  other  chemists,  but  made  more  com- 
pletely known  by  the  elaborate  researches  of  Wolcott 
Gibbs  and  F.  A.  Genth,  in  1857.  Among  these  may  be 
noted  the  clilorid  of  purpureo-cobalt  of  the  latter  chemists, 
tetragonal  in  form,  with  a  specific  gravity  of  1.802,  which 
includes  in  its  formula,  with  2Co,  not  less  than  6C1  and 
ION,  and  has  a  unit-weight  of  601 ;  the  chlorid  of  luteo- 
cobalt  of  Frdmy,  clinorhombic  in  form,  with  specific  gravity 
1.701,  which,  with  the  same  proportions  of  cobalt  and 
chlorine,  contains  not  less  than  12N,  and  has  a  unit-weight 
of  635 ;  and,  finallj,  the  orthometaphosphate  of  luteo- 
cobalt  of  Braun,  for  which  is  deduced  a  formula  including 
6Co  and  36N,  with  lOP,  giving  a  unit-weight  of  2540.* 
These  numbers,  like  those  deduced  for  alums,  ferrocyanids, 
sugars,  and  alkaloids,  represent  the  weight  of  the  chemical 
units  of  which  the  species  are  supposed  to  be  in  all  cases 
polymerides,  the  molecular  weights  of  which  are  as  yet 
unknown. 

§  116.  Still  farther  light  has,  however,  been  thrown  on 
the  subject  of  polybasic  salts  of  great  complexity  by  the 
studies  of  the  compounds  of  tungsten  and  molybdenum. 
It  was  in  1861  that  Marignac  made  known  the  existence 
of  two  types  of  silicotungstates,  in  which  one  molecule  of 
SiOa  is  united,  respectively,  with  ten  and  twelve  molecules 
of  WOg.  Subsequent  studies  by  Scheibler  made  us 
acquainted  with  series  of  phosphotungstates  in  which  six 
molecules  and  twenty  molecules  of  WO3  are  united  with 
one  of  P2O5 ;  while  Henri  Sainte-Claire  Deville  and  Debray 
made    known    analogous  phosphomolybdates.      Wolcott 

*  See  Gibbs  and  Genth,  Smithsonian  Contributions,  ix.,  1857,  and 
Amer.  Jour.  Science,  xxiii.-xxiv, ;  also  farther  Gmelin-Kraut,  Handbucb, 
iii.,  nub  voce  "  Kobalt," 


'''"•'        THE  Qi^ESTioi,  OP.      ' 

«>'«idered  a,"        '"^''''''''gstates  til  >       ^*  "<'»'  rec 
f  ^;nff  term  "  bZg^'X"  T"""^^''^  ^Z  'nk  l'"^"''"- 

Pliowc  acid  in  ti  !  ^  ■""•>'  also  take  thl    f'"'^P'""-ous 

«rge„  in  „,1'^^«  "ompiex  salts  anV''"  P'!''=«  of  phos- 

-"  phenyl!  appelttrt""  ™*«e  ZhW  "^'^"'' 
*h^  oompound^f^         '°  '"  "-^  capable  of  Z,^!^'""'*''^' 
^  "7-   Tiie  sii;„  .  "^  ""»  the 

the  subject  of  fa  tt      S'*«tes  of  Ma„Vnac  h 
'"und  that  the  L'jf"',  ^^^ralization  by  G»r  '"'°  ''e™ 
by  the  oxyds  J^  !"'"  "f  ««ea  therein  ^^'  '""^  "  is 

™°'jbde„„rGTh,  '!  *'  »".po.,nds  of  :   """^  »"'" 

"f;.fr<"»  vana  lic^S    t  *■""'"'  -vctl  "Iv T^^'^"  «"" 
which  he  r.„.  "  phosphoric  m-  ,        .     '^''nes  made 

j"«%  remarks-T"   '^ ''"  such  complex  ,      • 


388 


A  NATURAL  SYSTEM  IN   MINERALOGY. 


[VIII. 


.1  > 


h 


!    i 


1    3       t  ■ 


;» 


as  in  the  case  of  most  inorganic  compounds,  entirely- 
unknown."  He  adds  that  the  progress  of  bcience  "  tends 
constantly  to  show  that  the  structure  of  inorganic  mole- 
cules is  more  complex  than  we  formerly  supposed,"  *  and 
illustrates  the  great  complexity  in  these  compounds  by  a 
phosphotungstate  including  vanadium  and  barium,  repre- 
sented by  the  formula  6OWO3. 3PA.  2V2O,.  VO^.  18BaO  + 
I44H2O,  and  having  in  his  opinion  "the  highest  molecular 
weight  yet  observed,  20,058."  He  describes  another  simi- 
lar compound,  6OWO3.  2,^,0,.Y,0,N0z.  18BaO+150HA 
of  which  he  says,  "  It  is  almost  certainly  a  double  or  triple 
salt,  but  it  still  shows  how  five  different  oxyds  may  exist 
in  a  single  well  defined  and  beoutifully  crystallized  com- 
pound." Besides  these  soluble  and  hydrous  species,  all 
produced  in  the  moist  way,  is  the  curious  gold-colored 
insoluble  anhydrous  crystalline  body  discovered  by 
Wohler,  which  is  formed  at  a  red  heat,  and  is  generally 
described  as  a  tungstate  of  tungstous  oxyd  and  soda. 
This,  Gibbs  suggests,  may  possibly  be  represented  by 
I6WO3.  4WO2. 7NaO,  which  corresponds  to  a  unit-weight 
of  5002. 

§  119.  The  researches  of  Gibbs  upon  these  complex 
inorganic  acids,  resuming,  extending,  and  generalizing 
those  of  other  laborers  in  the  same  field,  are  of  much 

*  Wolcott  Gibbs  on  Complex  Inorganic  Acids;  Amer.  Jour. 
Science,  1877,  xiv.,  61;  also,  in  abstract,  Proc.  Brit.  Assoc.  Adv. 
Science,  Montreal,  1884,  p.  667,  and  more  fully  in  Amer.  Jour. 
Chemistry,  1879-188.3,  i.,  1,  217;  ii.,  217,  281 ;  iii.,  317,  402;  iv.,  377 : 
v.,  361,  391.  [See  farther  ibid.,  vii.,  392-417,  wherein  are  noticed 
the  pyrophosphates  of  Wallroth,  such  as  Cam.  Nai,.  (P207)9,  etc.  It 
would  appeal*,  says  Gibbs,  that  complex  molecules  similar  to  these 
"enter  directly  into  combination  with  twenty-two  molecules  of 
tungstic  oxyd "  to  form  the  still  more  complex  pyrophosphotung- 
states.  He  also  notes  the  molybdates  described  by  Struve,  in  1854, 
in  which  aluminic,  chromic,  ferric,  and  manganic  oxyds  are  united 
with  molybdic  oxyd,  and  give  such  salts  as  AI2O3.  i2M02.  6K20-f- 
20Aq;  and  MnoOa.  I2MO3.  5H2.0-l-21Aq;  and,  farther,  the  salts  of 
Parmentier,  AI2O3.  IOMO3.  2K20+15Aq,  etc.,  as  additional  examples 
of  salts  having  necessarily  high  molecular  weights.] 


VIII.] 


THE  QUESTION  OP  .xOLEcrLV,.^ 

^*.CCJLAR   WEIGHTS. 


889 


«iffnifica„co  to  the    h      ■  ^^^ 

"■organic  compou„dr  •!  "^'''"'  ^*™'=ture  of  so.,I  ^ 
would  notonh-.ll  .  '""^  affirmed  that  th  ^"""""^d 
b'-t  would  "be  fo  f  '°  '  """'"'t  >»ine "  otf '  ,  "  ^"''' 
"'■enn-ea.  tie  .ter'i/"  f -'^e  and  .";  rlT,'^'»>: 

o^pnic  chemistry  which 


890 


A   NATURAL  SYSTEM   IN   MINEUALOOY. 


[Vlir. 


(   » 


M 


'U 


I  t 


5  '^ 


'»( 


needs  not  fear  comparison  with  tlie  order  wliicii  reigns  in 
the  organic!  brancli  of  onr  science."  lie  ad-.is,  ''It  is  well 
to  be  reminded  that  complexity  of  constitution  is  not  the 
solo  prerogative  of  the  carbon  compounds,  and  that  before 
this  systematization  of  inorganic  chemistry  can  be  effected 
we  shall  have  to  come  to  terms  with  many  comi)ounds 
concerning  whose  composition  we  are  at  present  wholly  in 
ignorance,"  and  by  way  of  illustration  refers  to  the  com- 
plex inorganic  acids  of  Gibbs.* 

§  121.  Ilecognizing  from  the  beginning  of  this  inquiry, 
in  1853,  that  the  molecular  weights  of  mineral  species, 
while  far  exceeding  those  of  hydrocarbonaceous  or  so- 
called  organic  liquids  and  solids,  are  equally  unknown, 
we  have  sought,  nevertheless,  to  show  the  comparative 
condensation  in  different  mineral  spe  '.ies,  and  at  the  same 
time  the  existence  of  homologous  series  among  them,  by 
the  use  of  atomic  formulas.  In  these  the  results  of  chemi- 
cal analysis  are  reduced  to  their  simplest  term,  and  are 
presented  independent  c»f  all  hypotheses  as  to  the  struc- 
ture or  the  molecular  weight  of  the  species.  These  for- 
mulas suggest  to  the  chemist  something  more  than  the 
elemental  atoms  represented  by  the  symbols  employed. 
While  he  admits  in  the  simplest  mineral  silicate  or  oxyd 
the  existence  of  oxygen,  silicon,  and  one  or  more  metals, 
all  being  chemical  elements  physically  dissimilar  to  each 
other,  and  to  the  species  before  him,  the  tendency  of  the 
mind  is  to  conceive  this  as  made  up  of  identical  or  of 
similar  units  or  individuals.  The  justification  of  this 
mental  process  appears  in  the  fact  that  it  is  in  the  com- 
parison of  such  individuals  or  chemical  units  that  we  find 
the  chief  data  for  the  intelligent  study  of  the  chemical 
species.  Such  a  conception  of  units  underlies  the  doc- 
trine of  polymerism,  and  that  of  homologous  or  progres- 
sive series,  and  enables  us  to  compare  silicates,  oxj'^ds,  and 
carbon-spars   in   a  manner  the   correctness  of    which  is 

*  Sir  H.  E.  iloscoe,  Address  to  the  Chemical  Section  of  the  British 
Assoc.  Adv.  Science,  Montreal,  Aug.,  1884,  Report,  p.  G63. 


(i': 


\* 


VIII.] 


T«K  QTJESTION  OF   Mr»r 


881 


^"■■"i"'!   by  the   nl  '"'-'""■'•■''•        8 

"f  ".-e      '  If"'  '"■'•*■■-'  '  e  C  r  "■  "-  »t,.,,y  „ 
°^«en.  M  ,    u     ".">".. "Ht,  o.juiv,.^":"';'  "'  "  ■"""■ 
"■'"to!  ntonte  ''""■•  T"'""'  "•Zo.^'lrT"""'' 
divide  tI,evoTr7' J'   ''"^   «»'    »l«o,l    "  "'"■'•     ''"^ 

■         P't  """ivMuul,  ,S  """."""ience  sugL  ts  /l      ■     ""• '" 

«>■*  tl,e  sim2,f     ''*'"'  ^^  ""    mi.  eru      r'  '"'S'^' 
;"*oated,  the   ^t  /:r'.'^'""«  "-uW  u,"^'"'^  ""O 
for  eiich  specific  7      ^'^P  ■"  our  innuirv  „     .   *  ""  "l^ove 

designated  p.rf  '^'S'";  tbis  mean^w  f/' ™''"™d 
■■elation  of  th,  oh^'"^'  '»'"'  to  be  nT^l*  ''"^  ^-'en 
"«  .'exus  be tet  ";r' ,"'"'  'o  space  a  Sf''^"'^  '"e 

^i««Mo  gravity  „?'r;*"S^  »«  mean  „t' f  ^T^ '• '''"d '^ 
f.  .ted  by  D^  "!r  ''"  species  Ovate,-  be  ,t  ^'^'"  ''^  "'« 
designated  as   th      ^   '""""'y  ti,.«  ,,?  ?  ""'W'  ''epre- 

hypotJ^est  T      "''"""-n-    But  til       T'""'"^  '"  "'hioh 

attained  bv    .        •    ""'  «o  far  „.   ,, '      ,""  e^l'ression  is 
sponds  to  tit  !!"';"*■'  =■«  "uitv  tte  n      ,'""''™'  o«ly  be 

•^  stui  be  some 


■f.l"''  '■' 


(55 


89:i 


A    NATURAL   HYHTEM    IN    MINKUALOdV. 


[vm. 


lil! 


II 


h 
\ 


m 
m 


1 


■  <  ■ 


multii)lo  of  this  qiiiiiitity,  luid  will,  iit  the  siime  time,  be 
the  coinnion  imilti[)le  of  all  the  utoinie  volimies  tletluced 
from  various  chemiL'al  units. 

§  123.  Ill  ai)i)roac'liiug  the  consideration  of  this  molec- 
ular volume,  it  may  he  noted  that  while  in  salts  of  the 
same  ty|)e  the  specilic  gravity  sometimes  rises  with  the 
molecular  weight  of  the  base,  as  when  zinc  replaces 
magnesium,  or  lead  replaces  strontium,  in  carbon-sj)ars, 
the  specific  gravity  of  double  or  triple  salts  is  essentially 
the  same  as  tliat  of  the  corresi)onding  salts  with  a  single 
base,  as  may  be  seen  by  comparing  the  densities  of  sim|)Ie 
and  double  hydrous  sulphates,  orthophos[)hates,  and 
tartrates;  so  that  the  value  of  P,  deduced  from  the  more 
complex  salts,  considered  as  chemical  units,  will  be  essen- 
tially the  same  as  that  of  the  apparently  simple  salts  of 
the  type.  Taking,  then,  of  the  anunonia-cobalt  salts 
(§  115),  not  the  simple  chlorids,  but  Braun's  complex 
phosphate  of  luteo-cobalt,  with  a  unit-weight  of  2540  (of 
which  the  specific  gravity  is  undetermined),  we  have,  if 
we  assume  for  it  a  density  of  1.701  (which  is  that  of  the 
chlorid  of  the  same  base),  a  unit-volume  of  not  less  than 
1493. 

§  124.  The  complex  tungstates  give  still  higher,  vol- 
umes. The  golden  anhy  ^rous  tungstico-tungstate  of  so- 
dium has  a  specific  gravity  of  6.617,  while  for  two  allied 
tungstic  compounds,  the  one  potassic  and  the  other  sodic, 
are  given  the  numbers  7.60  and  7.28,  showing  that  these 
are  similar  in  condensation  to  the  anhydrous  calcic  and 
ferrous  tungstates,  scheelite  and  wolfram.  For  the  solu- 
ble and  hydrated  polytungstates,  Scheibler  found  the 
specific  gravity  of  4W*O3.Na2O+10Aq  to  be  3.987,  while 
that  of  the  corresponding  barium  salt,  with  9Aq,  is  4.298, 
and  that  of  I4WO3. 6Na,0+32Aq  is  3.846.*  The  density 
of  the  complex  hydrous  phospho-vanadio-tungstate  of 
barium  described  by  Gibbs  (§  114),  with  a  unit-weight 
of  20,058,  is  unknown,  but,  if  we  assume  for  it  the  number 

*  See  Constants  of  Nature,  by  F.  W.  Clarke,  Tart  i.,  83. 


vni.j 


'""  ■•'••"lily  uttm-  ,  1  "•■'«'"«  ■'«  timt  1, '       '  <="">«'>rml 

mineral  spel       '  "'  '"o  ''"o  ..mue.l  '  '""'""•'^l'- 

8«itcd  bv  ,  .  ■"'^''  '^"t  their  vo  n    """"»»">  molec- 

'>•!*  a  eorri"      ,    '""'"  ■""""'«  units   1        "'  "'°'^«"!e 
three  nf  fi.  formula  for  fi,„  "•     ^"t  as 

"^^e  manner  th^    1  ^^o^^astonite  hv  OQa/     '''^^  V   by 

'-^"^^  albite     'nn     '.'"""^  ^"'"^«e  of  the  L? ^^^'^'^^'^o^-     J" 

'?*'?'"""•  •'  "•  ""=""■  ==.'"5 

-tt  Will  be  evifipnf-  +1,  x  «-   ui 

"'  that  attempts  lifce  these  at ,    , 

^nese  at  moleeujar 


394 


A  NATURAL   SYSTEM   IN  MINERALOGY. 


[VIII. 


Sill 


li    i: 


foi-nuilas  are  of  value  only  so  far  as  they  serve  for  illustra- 
tion, since  the  unit-volumes  assigned  to  the  various  spe- 
cies are  but  approximations,  and  the  molecular  volume, 
4666,  wliich  has  been  assumed,  is  based  on  a  supposed 
specitic  gravity,  and  can  only  be  conjectured  to  be  not  far 
from  the  truth.  A  series  of  careful  studies  of  the  specific 
gravities  of  various  salts  of  the  complex  inorganic  acids 
may  furnish  us  with  more  trustworthy  data  for  sindlar 
calculations.  Meanwhile,  it  is  to  be  repeated  that  the 
formulas  here  given  for  pyroxene,  wollastonite,  and  the 
feldspars,  are  of  value  only  as  they  serve  to  illustrate  our 
conception  of  the  complex  constitution  of  these  silicates. 
For  the  purposes  of  comparison,  and  for  the  elucidation  of 
polymerism  and  homologies,  the  unit-volumes  which  we 
have  calculated  for  the  preceding  tables  of  species  of  the 
different  tribes  of  silicates,  serve  every  purpose,  and  show 
in  a  simple  manner  the  relative  condensation  of  tlie  mole- 
cule in  the  various  species.  Attempts  to  devise  structui-al 
formulas  for  these  very  complex  silicates  appear,  in  the 
present  state  of  our  knowledge  of  their  constitution,  to  be 
premature,  and,  at  the  same  time,  unnecessary. 

§  126.  We  have  seen  in  our  studies  of  the  volume  of 
mineral  species  two  cases ;  the  first  being  that  in  which,  in 
analogous  compounds,  the  density  varies  with  the  unit- 
weight,  so  that  the  species  compared  have  identical  unit- 
volumes  ;  and  the  second,  that  in  which  species,  otherwise 
analogous,  have  such  densities  as  give  very  unlike  unit- 
volumes,  —  a  fact  showing  the  existence  of  progressive  or 
homologous  series  of  polymerides,  as  illustrated  in  the 
case  of  many  silicates  and  carbon-spars.  Examples  of 
these  differences  are  seen  in  the  chlorids  of  potassium  and 
sodium,  the  latter  of  which  itself  presents  remarkable 
differences  in  density.  Thus,  while  the  numerous  deter- 
minations for  potassium-chlorid  do  not  vary  very  much 
from  a  specific  gravity  of  1.99,  the  careful  observations  of 
different  experimenters  with  sodium-cMorid  show  varia- 
tions from  2.011  by  Playfair  and  Joule  to  2.15-2.16  by 


f    . 


\k 


■V 


.^«^.r-.>*.,^^,M^.)..^,f|^    (jy-gjp,,.^,,.,- 


VIJI.]         THE  QUESTION   OF  MOLECULAR   WEIGHTS. 


395 


I  ?!' 


Stolba,  2.195-2.204  by  Deville,  and  2.24-2.26  by  Mohs  and 
Filhol.*  With  these  various  determinations  of  density 
before  us,, says  Henry  Wurtz,  "we  are  forced  to  infer  the 
existence  of  four  modifications  of  sodium-chlorid,"  while 
he  adds,  "common  salt  is  far  from  being  alone  among 
saline  combinations  in  its  passage  into  livers  modifications 
or  allotropes.  On  the  contrary,  the  circumstance  is  almost 
universal  among  salts,  throughout  the  whole  range  of 
chemistry."  It  would  seem,  in  fact,  that  such  variations 
in  specific  gravity  in  a  homogeneous  solid  (like  those  in 
the  specific  gravity  of  a  vapor  or  gas  at  constant  pressure 
and  temperature)  can  have  but  one  meaning ;  which  is 
that  these  sodium-chlorids  of  different  densities  are  so 
many  distinct  species,  related  to  each  otlier  as  fibrolite  to 
cyauite,  as  lyncurite  to  zircon,  and  as  tridyniite  to  quartz. 
§  127.  All  such  allotropic  variations  in  compound  spe- 
cies, which  are  marked  not  only  by  differences  of  density, 
but  in  many  cases,  if  not  in  all,  by  differences  in  hardness 
and  in  chemical  relations,  are  by  Henry  Wurtz  conceived 
to  be  "dependent  on  a  variability  through  a  certain 
(sometimes  not  very  narrow)  range  of  diameters,  of  one 
element,  always  the  basylic  or  electropositive  of  a  group, 
—  in  salts,  therefore,  always  the  metallic  base."  Accord- 
ing to  him,  the  volumes  of  elemental  molecules,  that  of 
oxygen  excepted,  "  are  expressed  by  quantities  having,  at 
the  temperature  of  ice-fusion,  the  relations  of  even  cubes 
of  a  series  of  whole  numbers,  of  which  series  the  number 
pertaining  to  the  molecule  of  ice  at  this  temperature  is 
27."  This,  he  adds,  is  "a  standard  volume  in  nature,  to 
which  the  volumes  of  all  liquid  and  solid  bodies  may  be 
compared  when  at  the  same  temperature."  The  cube  roots 
of  these  numbers  are  by  Wurtz  designated  as  "  molecular 
diameters,"  and  the  variations  in  specific  gravity  in  the 
different  forms  of  sodium-chiu::id  are  explained  by  supi)os- 
ing  the  diameters  of  one  or  more  of  the  sodium  molecules 
in  a  complex  group  including  4NaCl  to  vary  from  23  to  24 

*  Constants  of  Nature,  by  F.  W.  Clarke,  Part  i.,  30. 


!      4 


396 


A   NATURAL   SYSTEM   IN   MIKEKALOGY. 


[VIII. 


/■!; 


h 


'.  t 


and  26,  the  diameter  of  the  chlorine  molecules  remaining 
invariable.*  This  method  enables  him,  by  admitting  more 
or  less  complex  groups,  in  which  the  similar  elemental 
moleciiles  have  varying  diameters,  to  approximate  closely 
to  the  densities  of  liquid  and  solid  species. 

§  128.  To  such  a  scheme  it  must  be  objected  that  it 
involves  the  notion  of  existing  elements  or  groups  of 
elements,  dissimilar  to  each  other  as  well  as  to  the  spe- 
cies under  examination.  The  conception  that  the  chemical 
elements  enter  as  such  into  combination,  and  there  retain 
their  volumes,  is,  it  is  believed,  inadmissible  in  chemi- 
cal philosophy.  The  view  which  I  have  constantly  main- 
tained, and  have  set  forth  i,i  the  present  essay,  it^  that 
differences  in  density,  such  as  we  have  just  considered,  are 
not  dependent  on  variations  in  the  hypothetical  units 
adopted  for  convenience  in  calculation,  but  belong  to  the 
species  as  an  integer,  and  correspond  to  a  greater  or  less 
condensation  of  its  mass,  —  that  is  to  say,  to  the  identifi- 
cation in  a  constant  volume  of  a  greater  or  less  number  of 
chemical  units.  The  very  terms  of  atom  and  molecule, 
which  we  apply  to  these  imaginary  units  and  to  the  mass, 
are  concessions  to  a  popular  terminology  borrowed  from 
physics,  and  are  not  only  inadequate  but  to  a  certain  ex- 
tent misleading  when  applied  to  chemical  operations.  I 
venture  in  this  connection  to  reprint  the  words  employed 
in  1874 1  in  the  discussion  of  this  same  question :  — 

"The  phenomena  of  chemistry  lie  on  a  plane  above 
those  of  physics,  and,  to  my  apprehension,  the  processes 
with  which  the  latter  science  makes  us  acquainted  can 
afford,  at  best,  only  imperfect  analogies  when  applied  to 
the  explanation  of  chemical  phenomena,  to  the  elucida- 
tion of  which  they  are  wholly  inadequate.  In  chemical 
change,  the  uniting  bodies  come  to  occupy  the  same  space 

*  Geometrical  Chemistry,  by  Henry  Wurtz,  page  72,  1876;  reprinted 
from  the  American  Chemist,  March,  1876. 

t  A  Century's  Progress  in  Theoretical  Chemistry:  being  an  address  at 
the  grave  of  Priestley,  July  31,  1874,  reprinted  from  the  American  Chem- 
ist for  August  and  September,  1874.    See,  also,  ante,  pp.  13-15. 


^"^•^  A  KATITBAL  SYSTEM  X^  ,„^,, 

a'^  the  same  tinie  an.1  fi      •  ^^^ 

seen  to  be  no  loi,p-Ir     ^     '^  ""Penetrabilitv  nf 
"masses  is  confS  V'  ^"'^ '  ^^^«  volume  o/i,       '"^^^^^"  ^« 
cal  characte   tS^^  ^"^  "^^  ^'-  Pi^yX:/.^;^  .t'"^^"-^ 

:      «i*  bids  t:d7„\:t  ^"T'  "'  ••"-  an'r:!?,  °^ 
'-ien  we  give  a  e<^.o;  1%    P'"'"  "''^""''''i  affinreif"'^^/ 

nature,  and  „f  t  "f^-'^^  of  i,^  ^  tl^.'T"""' 

and  faet.' "  '^'^  '»  distinguish  betlel       '^'"■^  "^ 

§  129.   We  her«  *  ™njeoture 

"nd,  as  a  fecessl""""^^  ""^  P'an  of  ehl'^'T'''-  ^'^"« 

N^*"ai  Systr Xr" ,"'^' '°'^-  ' "fot Te'"K".''''«=;-" 
set  forth  ,-r.  ^''"iieraloffv      W^  i  ®  '^''^«is  of  ;. 

o^yds,  which '!;  ,*'"*  '""'•»  briefly  to    i,         P""«'I''es 

over,  g,-,::   °  '  5;'^er  of  MetalUtel^te"!  0/^*"e.  " 

fication  whi<.h  o   ;  '    "^  an  outline  of  „      !  ^^'''  '"o'e- 

and  already  el?  ^  Tf  "«^  'anguage  "!"'?"•    ^'  '^ 
^  »"ed,  .n  §  18.  that  alf  eh^''^'  '•"  186V. 

unoal  species  really 


1  :   i,M  '  i: 


398 


A    NATTJllAL   SYSTEM   IN   MINERALOGY. 


[Vin. 


\'l 


Hi 


u 


*  \ 


lit 


belong  to  the  mineral  kingdom,  and  that,  "in  this  extended 
sense,  mineralogy  takes  in  not  only  the  few  metals,  oxyds, 
sulphids,  silicates,  and  other  salts  which  are  found  in 
nature,  but  also  all  those  which  are  the  products  of  the 
chemist's  skill.  It  embraces,  not  only  the  few  native 
resins  ar:l  hydrocarbons,  but  all  the  bodies  of  the  carbon 
series  made  known  by  the  researches  of  modern  chemis- 
try." A  Manual  of  Mineralogy,  based  on  the  principles 
here  set  forth,  such  as  we  hope  to  prepare,  would,  however, 
be  limited  to  the  consideration  of  natural  species. 

§  130.  In  conclusion,  we  give  three  synoptical  tables, 
in  which  are  resumed,  under  their  respective  tribes,  the 
principal  species  of  the  three  sub-orders  into  which  we 
have  divided  the  order  of  Silicates.  In  these  tables  the 
dominant  atomic  ratios  are  given  in  the  left-hand  columns, 
while  more  rarely  recurring  ratios,  as  in  danalite,  schorlo- 
raite,  sloanite,  etc.,  r  re  placed  in  parentheses  after  the 
names  of  the  species,  which  are  in  their  appropriate  posi- 
tions in  their  respective  columns.  In  the  case  of  Tribe  4, 
the  exigencies  of  construction  have  caused  its  displace- 
ment in  the  table,  and  hence  the  atomic  ratios  of  its 
included  species .  are  there  also  appended.  The  calcu- 
lated values  of  V  are  given  with  the  respective  tribes. 
These  tables  are  necessarily  much  abridged,  and  should  be 
studied  in  connection  vdth  the  systematic  grouping  of 
sub-orders,  tribes,  and  spesies,  to  be  found  undor  §  55  of 
the  present  essay. 

For  the  colloid  tribes  the  reader  is  referred  to  pages 
374-375,  where  the  very  variable  composition  of  the  vit- 
reous products  of  igneous  fusion  is  insisted  upon.  As 
regards  th'>  limits  of  species  in  such  cases,  the  question 
which  arises  is  similar  to  that  presented  by  the  various 
intermediate  feldspars  and  scapolites,  already  discussed, 
and  by  the  intermediate  carbon-spars,  and  is  one  inti- 
mately connected  with  the  high  molecular  weights  which 
must  be  assigned  to  mineral  species. 


il 


I'i 


VIII.J 


^  NATURAL  SYSTEM 


IN  MiNEltALOGY. 


399 


'I      '■, 


400 


A  NATURAL   SYSTEM  IN  MINERALOGY. 


[VUI. 


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IX. 


THE  HISTORY  OF  PRE-CAMBRIAN  ROCKS. 

The  following  suuitnary  is  in  good  part  a  condensation  from  the  account 
given  in  my  volume  on  "  Azoic  Hocks,"  to  wliich,  for  details  previous  to  1878,  tlio 
reader  is  rtiiorred.  His  intended  to  servo  as  an  introduction  to  the  two  succeeding 
essays  in  whicli  certain  parts  of  the  history  of  these  roclts  are  discussed.  The  diief 
portion  of  the  text  wiis  published  in  the  Anierloan  dournal  of  Science  for  -May, 
18S0.  There  are,  however,  many  later  a<iditions,  principally  from  a  paper  read 
before  the  Britisli  Association  for  the  Advancement  of  Science,  at  Montreal,  in 
August,  1H«4,  and  published  in  the  Geological  Magazine  of  London  for  Novembf 
of  that  year. 

I.  —  PKE-CAMBKIAN  ROCKS  IN  NORTH  AMERICA. 
§  1.  It  is  proposed  to  give  in  these  pages  a  brief 
analysis  of  the  principal  facts  ah-eady  publislied  else- 
where respecting  the  systematic  sub-division  and  classili- 
cation  of  the  pre-Canibrian  rocks.  These,  according  to 
the  writer,  present  in  North  America,  and  elsewhere,  an 
invariable  succession  of  crystalline  stratiform  masses, 
divided  by  him  into  several  great  groups,  the  constituents 
of  which  become  progressively  less  massive  and  less  crys- 
talline until  we  reach  the  sediments  of  paleozoic  time, 
of  which  the  Cambrian  is  regarded  as  the  basal  member. 
Since  all  of  these  pre-Cambrian  rocks,  with  the  exception, 
perhaps,  of  the  lowest  or  fundamental  gneiss,  present 
evidences,  direct  or  indirect,  of  the  existence  of  organic 
life  at  the  time  of  their  deposition,  it  seems  proper  to 
include  them  under  the  general  title  of  Eozoic,  proposed 
by  Sir  J.  W.  Dawson.  That  of  Archaun,  employed  by 
some  geologists  to  designate  these  pre-Cambrian  rocks, 
appears  too  indefinite  in  its  signification,  and,  moreover, 
is  not  in  accordance  with  the  nomenclature  generally 
adopted  for  the  great  divisions  succeeding.  These  Eozoic 
rocks  include  both  the  Primitive  and  the  Transition  divis- 
ions of  Werner. 

402 


I'l 


IX.J 


A  Q      ».« 1 


§  2    As  r         1  ""^  --^'^wiCA.      403 

American  crvSl'ir   ^^'  "'"'^^  ^'^'^^^J  of  our  I.n      ,    , 
New  V    ?        "''^  ^  ^^'"'"y  ffi.oissfp  f      ''^^.^''^^itljologicai 

'-->■  as :  ;:*  ™  ^-^  Je..e;  h  'i  ;t  "■"^^^ 

southern   Nevv  y ""'"'"''  "  S-'oa*  part  o    T'^  "^""^  "^ 
class  he  refenwl  .11  .,      """"■!''''«  >ocks     T„  *i         '''^■ 

-hat  he  had  dose;    ed^a«  fti '"'"  "'""'^'-  ^  S'^    pttoT 

n  his  Metamorjihie   elass     "t7  ™f  "°'  '°  ^'  '""'"ded 

Jiitchell  and  of  r„„i.    ,  "'«  subsequent  i,v,         " 

f'e  views  of  V  "  '''''^^'  lioivever  Pl„n,r      *"^  "^ 

nr»n     .  ?    ^anuxeniand  Jf„,t,-        '  ™ai'ly  established 

inown  tn  R- T'"'"' S^"'"™c  series  in  P       . 

Me'a„,o,,,hio  ,.athe,.  tl!::?  1'°,^;.'  "A":^'  ' 


I.  .:•'* 


i 


•I'  'I 

3 
/ 


404  THE  HISTORY  OF   PRE-CAMURIAN   HOCKS.  [IX. 

described  by  Logiin,  in  1847,  as  consisting  of  a  lower 
group  of  hornblendic  gneisses,  without  limestones,  and  an 
upper  group  jf  similar  gneisses,  distinguished  by  inter- 
stratified  crystalline  limestones. 

These  rocks  were  found  by  Logan  and  by  Murray  to  be 
overlaid,  both  on  the  north  shore  of  Lake  Superior  and  in 
the  valley  of  the  upper  Ottawa,  by  a  series  consisting  of 
chloritic  and  epidotic  schists,  witii  bedded  greenstones, 
and  with  conglomerates  holding  pebbles  derived  from  the 
ancient  gneiss  below.  The  same  overlying  series  had,  as 
early  as  1824,  been  described  by  Bigsby  on  Lake  Superior, 
and  by  him  distinguished  from  the  Primary  and  classed 
with  Transition  rocks. 

§  4.  Labradoritic  and  hypersthenic  rocks,  like  those 
previously  described  by  Emmons  in  the  Primary  region 
of  northern  New  York,  were,  in  1853  and  1854,  discov- 
ered and  carefully  studied  in  the  Laurentide  hills  to  the 
north  of  Montreal,  when  they  were  described  as  being 
gneissoid  in  structure,  and  as  interstratified  with  true 
gneisses  and  with  crystalline  limestones.  In  1854,  the 
writer,  in  concert  with  Logan,  proposed  for  the  ancient 
crystalline  rocks  of  the  Laurentides,  including  the  lower 
and  upper  gneissic  groups  already  mentioned,  and  the 
succeeding  labradoritic  rocks  (but  excluding  the  chloritic 
and  greenstone  series),  the  name  of  Laurentian.  In  the 
same  year  he  wrote  that,  "in  position  and  lithological 
Qharacters,  the  Laurentian  series  appears  to  correspond 
with  the  old  gneiss  formation  of  Lapland,  Finland,  and 
Scandinavia."  *  Subsequently,  in  an  essay  published  in 
1856,  these  gneisses  of  Scandinavia,  together  with  the 
oldest  gneisses  of  Scotland,  were,  on  lithological  and  on 
stratigraphical  grounds,  referred  to  the  Laurentian  series, 
and,  at  the  same  time,  the  name  of  Huronian  was  pro- 
posed for  the  chloritic  and  greenstone  series,  which  had 
been  shown  to  overlie  unconformably  the  Laurentian  series 
in  Canada. 

*  Amer.  Jour.  Science,  1854,  xix.,  195. 


1 1' 


rx.] 


ROCKS   IN  NOIITH  AMERICA. 


I';;;'  ''oscribc-,1  ,,,,0  ,,„„,:;;;;,';;,  ."f  •  '''"^ter  a„,l  Whitney 
^"l;e.-.or  „s  co„»fit„ti,Kr  „  '  V  "'"■"'"""  """ks  of  L,ke 
«-!„,  with  g,,.„ia,«,  „' "  ;;J37"^  »f.' ™'  of  Meta,„o..„l,  c 

^f'""?  fo  a  single  mC  ,yT  '  '■"'^''  "'  "'»  «gion 
"^^o.v„u,„„  „f  Kin,I„,  "•  ;7^''  "  e.-.;.n  tic  nucleus.  The 
Credne,-,  of  Uvooks  ,.nd  i"„       I,'""'  ""=  '"'<"•  studies  of 

of  the  P,™„.,,  ,,,;"  I^J^™-^  as  also  f„,,,»;„  .;■; 
seen,   supposed  to   be   iLf,:  ""  ™   '"'ve  alieadv 
?;ooks  in  New  E„g,a„d  flT; ,  ''"'^"^''^  »t,-atu.      Th  ^ 
•  ■'««  ""d  limestones  of  al  tI     '''°'""°"  "f  "'<'  <l"artz! 

Ne-  England  S'rtJt^r"""-  -'™'«  «f  western 

"ere  themselves  more  Tn- ^^•''^"'"'"^  S>'eissic  system 
stone,  which  he  regarded  '"  *'""  ">"  Se-'litlmi  Id' 
•'r •     While  he  sSs  d  :L""  "'"'-'"«"  of  the  Po  t 

-"ed  by  him  AzotTo^tTorelt^dTf  "^^"•■'^'^ 

connected  stratigraphically 


400 


THK   IIISTOKY   OK    I'UE-CAMUUIAN    UOUK8. 


[IX. 


IMii. 


-m 


with  the  base  of  tlio  Piileozoic  Hcries,  ho  ncvertlioless 
assigned  them  to  a  positif.i  below  the  base  of  the  Now 
Yolk  system  ;  thus  reco^'ni/iiig  in  Pennsylvania,  beneath 
this  hori/on,  two  nneonl'orniable  [groups  ol"  erystallinc  roeks. 
Tiie  existence  amonj;'  these  newer  crystalline  schists  of 
Pennsylvania,  of  a  series  tiistinet  from  the  lluronian,  and 
representing  the  White  Mountain  or  Montalban  rocks 
(the  IMiiladelphia  and  Manhattan  gneissic  group),  had 
not  then  been  recognized.  A  farther  discussion  in  some 
detail  of  these  rocks  in  Pennsylvania,  will  be  found  farther 
on.  Essay  XI.,  §§  37-42. 

§  8.  'J'he  views  of  II.  D.  Rogers  with  regard  to  tlie 
crystalline  schists  of  the  Atlantic  belt  were  thus,  in 
effect,  if  not  in  terms,  a  return  to  those  lield  by  Eaton 
and  by  Ennnons,  but  were  in  direct  oi)p()sition  to  that 
maintained  by  Mather,  which  had  been  adopted  at  that 
time  by  Logan  and  by  the  present  writer.  The  belt  of 
chloritic  and  cpi(k)tic  schists  with  greenstones,  serpen- 
tines, and  steatites,  the  extension  of  a  i)art  of  the  Azoic 
of  Rogers,  which,  through  western  New  England,  is 
traced  into  Canada  (wliere  it  has  been  known  as  the 
Green  Mountain  range),  was,  previous  to  18G2,  called  by 
the  geological  survey  of  Canada,  "  Altered  Hudson  River 
group."  It  was  subsequently  referred  to  th  Upper 
Taconic  of  Ennnons,  to  which  Logan,  at  that  date,  gave 
the  name  of  the  Quebec  group,  assigning  it,  as  had  long 
before  (in  184G)  been  done  by  Einmons,  to  a  Cambrian 
horizon  between  the  Potsdam  and  the  Trenton  of  tlie 
New  York  system.  Henceforth  the  crystalline  schists  in 
question  were  by  Logan  designated  the  "  Altered.  Quebec 
group." 

§  9.  In  1862  and  1863  ai:)peared,  independently,  two 
imjiortant  papers  bearing  on  the  question  of  the  <ige  of 
these  crystalline  rocks.  The  first  of  these  was  by  Thomas 
Macfarlane,  who,  after  a  personal  examination  of  the 
tliree  regions,  compared  the  lluronian  of  Lake  Huron 
and.  the  Green  Mountain  range  of  Canada  with  portions 


JQL] 


'^"tKS   IN    xoj.nr   AMKKICA. 


407 


ot  the  IJiscliicfei.  or  P  •    •  • 

',;"«'vene  l„t,vc.„„   tl,     ,:;;'e'™  *■'''"'"  "■'"■^''-  '■"  ^'""™y. 

«"l'"«t  "tn.lont  „f  „,e  I,,    „       '  •,  "»  '"'  '"'vo  .„.„,  ll,, 

ta,„bn„„,  l,ut  we.e   H,„  " "  1 '  r'  '"  "">■  ''^""o  h.  called 
U»cl.iefo,..     The  c,.„c.|„  i„     '      A  '    ?   ',"    "''   ''"'•^''^W'"- 
■n  connection  with  t|,e  vie    "    k  ".f "'"""  '"-'•■»  ""'ice,l, 
■      Norway,  in  ••  The  Ceoi,  J  „  e"  ,tr  ''•'' ,""  "'""'  '■"^^''  " 
eo'^raa^on,  between  the  New  E  't'    ',"  '«"3,  with  fa.the,- 
"■■'1  the  II„,,.„i,„,  i,,,^  „„f    ;  ^  «'"'"!  ^OxaUline  »el,i,s,„ 

-.o,nt,,eview»oa,,e.i.^-/---X-^^^^ 

-'o^-;:'St;s::.:l7'-"'-'^-e,.ie, 

S'-u,,,  whiel,  ineln,lecl  u  lowe    .nd'",',','"  "'  "'?  *'"'<"'™"k 
"  Jomt  report  of  Matthew    ™'     "'''"•"■  '""»'""•     In 
^"■■vey  of  Canada,  i„  ISot  h"  o  r^  I   '^  '"  '''"  ^""'"Si-'l 
overhud  uneonfonnahly  hy   I  r>.l^f         'V''''"''"''''  '°  be 
"""le  known  a  Lower  cl.t^anM '"  ""'=''  "'"" ''"^ 
;vere  compared  with    tiTllZJ      "7""'^  *""""■  ""d 
lower  division  of  the  Col  1„.„  i         '"   "^  ^""'«'»-      The 
-  ;..cludi„g  a  larg   am™,    of  S'";  T  """  ^'"-"'^  ^ 
ond  of  bluish  and  reddish  nor,  I,v  ''''""""'=  1""''^"« 

report  was  described,  nnde    tl  7 ,  T''    '"  «'«  same 

f  cup,  a  series  lithoW,,  "'!;,"";""  "*  "''  Blooras^ury 
but  apparently  resting  ?,  '    fe  Men"'-  '"  ""  ^""'"■"t^ 
fo>is,life,.o„s  Upper  Devon  »n    ,    "=™"''  ""d  °™ri'dd  bj^ 
apposed  togradnate      TirWoom'^  ""°    "'"»"   ''  -«» 
ore  regarded  as  altered  Uppe"   Dev"'^- ^'■°""  ™^  "■«■■«- 
'anty  to  the  pre-Cambria,.  Coldb^ooT'""''  "'"'  '''  '""'- 
supposrng  both  groups  to  consist  ,nt    """  '"P'"'"'"  ''>' 
rocks.  ^      ^  "*'^' "> '"rge  part  of  volcanic 


I    (! 


1 


• '  t 


!     , 


.  n 


408 


THE   HISTORY   OF  PRE-CAMBRIAN  ROCKS. 


[IX. 


§  11.  In  1869  and  1870,  however,  the  writer,  in  com- 
pany with  the  gentlemen  just  named,  devoted  many- 
weeks  to  a  careful  study  of  these  rocks  in  southern  New 
Brunswick,  when  it  was  made  apparent  that  the  Blooms- 
bury  group  was  but  a  repetition  of  the  Coldbrook,  on  the 
opposite  side  of  a  closely  folded  synclinal  holding  Mene- 
vian  sediments.  These  two  areas  of  pre-Cambrian  rocks 
were  accordingly  described  by  Messrs.  Matthews  and 
Bailey  in  their  report,  in  1871,  as  Huronian,  in  which  were 
also  included  the  similar  crystalline  rocks  belonging  to 
two  other  areas,  which  had  been  previously  described  by 
ibe  same  observers  under  the  names  of  the  Kingston  and 
Coastal  groups,  and  by  them  regarded  as  respectively 
altered  Silurian  and  Devonian. 

§  12.  After  studying  the  Huronian  rocks  m  southern 
New  Brunswick,  and  their  continuation  along  the  eastern 
coast  of  New  England,  especially  in  Massachusetts  (where, 
also,  they  are  overlaid  by  Meneviau  sediments),  the 
writer,  in  1870,  announced  his  conclusion  that  the  crys- 
talline schists  of  these  regions  are  all  of  them  pre-Cam- 
brian, and  lithologically  and  stratigraphically  equivalent 
to  those  of  the  Green  Mountain  range  of  western  New 
England  and  eastern  Canada.  These  he  further  declared, 
in  1871,  to  be  a  prolongation  of  the  newer  crystalline  or 
Azoic  schists  of  Rogers  in  Pennsylvania,  and  the  equiva- 
lents of  the  Huronian  of  the  Northwest.  The  pre-Cam- 
brian age  of  these  crystalline  schists  in  eastern  Canada 
has  now  been  clearly  proved  by  the  presence  of  their 
fragments  in  the  fossiliferous  Cambrian  strata  in  many 
localities  along  the  northwestern  border  of  the  Green 
Mountain  belt,  and  farther  by  the  recent  stratigraphical 
studies  of  the  geological  survey  of  Canada. 

§  13.  In  close  association  with  these  Huronian  strata 
in  eastern  Massachusetts  is  found  a  great  development  of 
petrosilex  rocks,  generally  either  jaspery  or  porphyritic 
in  character,  and  sometimes  fissile,  whicli  by  Edward 
Hitchcock  were  regarded  as  igneous.     These  were  now 


'i5  W 


trata 
it  of 
h'itic 
kvard 
I  now 


IX.] 


PEE-CAMUKIA"!^    HOCKS   IN   NORTH   AMEUICA. 


409 


found  to  be  identical  with  tlie  rocks  designated,  by 
Matthews  and  Bailey,  feldspathic  quartzites  and  silicious 
and  porphyritic  slates,  which  form  the  chief  part  of  the 
Lower  Coldbrook  or  inferior  division  of  the  Huronian 
series  in  New  Brunswick.  The  petrosilexes  of  Massachu- 
setts were,  after  careful  examinations  by  the  writer, 
described  by  him,  in  1870  and  1871,  as  indigenous  strati- 
fied rocks  forming  a  part  of  the  Huronian  series.  He 
subsequently,  in  1871,  studied  the  similar  rocks  in  south- 
eastern Missouri,  and,  in  1872,  on  the  north  shore  of 
Lake  Superior,  but  was  unable  to  find  them  in  the  Green 
Mountain  belt,  or  in  its  southward  continuation,  until,  in 
1875,  he  detected  them  occupying  a  considerable  area 
in  the  South  Mountain  range,  in  southern  Pennsylvania. 
The  stratified  petrosilex  rocks  of  all  these  regions  were 
described  in  a  communication  to  the  American  Associa- 
tion for  the  Advancement  of  Science,  in  1876,  as  appar- 
ently corresponding  to  the  halleflinta  rocks  of  Sweden, 
and,  having  in  view  their  stratigraphical  position,  both  in 
that  country  and  in  New  Brunswick,  they  were  then  "  pro- 
visionally referred "  to  "  a  position  near  the  base  of  the 
Huronian  series."  Their  absence  in  the  Huronian  belt  in 
western  New  England,  and  in  the  province  of  Quebec,  as 
well  as  at  several  observed  points  of  contact  between  the 
Laurentian  and  the  well  defined  Huronian  in  the  North- 
west, led  to  tlie  suspicion  that  these  rocks  might  belong 
to  an  intermediate  group  (since  named  Arvonian).  They 
may  be  briefly  described  as  a  series  of  stratified  rocks, 
composed  essentially  of  petrosilex,  often  passing  into  a 
quartziferous  porphyry.  There  are  found  with  it  strata 
of  vitreous  quartzite,  and  thin  layers  of  soft  micaceous 
schists,  besides  great  beds  of  hematite,  and,  more  rarely, 
layers  of  crystalline  limestone. 

§  14.  C.  H.  Hitchcock  has  pointed  out  that  the  char- 
acteristic Huronian  rocks  do  not  form  the  higher  parts  of 
the  Green  Mountain  range  in  Vermont,  which  he  con- 
ceives to  belong  to  an  older  gneissic  series.    He,  however. 


.i ' '. 


410 


THE   HISTORY   OF   PRE-CAMBRIAN   ROCKS. 


[IX 


in  Ids  fiiuil  report  on  the  geology  of  New  llampsliire,  in 
1877,  adopts  the  name  of  Huronian  for  the  cuystalline 
rocks  of  the  Altered  Quebec  group  of  Logan,  which 
make  up  the  chief  part  of  the  Green  Mountain  range  in 
Quebec,  are  largely  developed  along  it  in  Vermont,  and 
appear  in  a  parallel  range  farther  east,  which  extends 
southward  into  New  Hampshire.  In  his  tabular  view  of 
tlie  geoguostic  groups  in  this  State,  Hitchcock  assigns  to 
these  rocks  a  thickness  of  over  12,000  feet,  with  the  name 
of  Upper  Huronian ;  while  he  designates  as  Lower  Huro- 
nian the  petrosilex  series  of  eastern  Massachusetts,  already 
noticed,  where  these  rocks  are  of  great,  though  unde- 
termined, thickness.  The  similar  petrosilex  or  halleflinta 
rocks  in  Wisconsin,  where  they  have  lately  been  described 
by  Irving  as  Huronian,  have,  according  to  this  observer, 
a  thickness,  in  a  single  section,  (  f  3200  feet.  They  here 
sometimes  become  schistose,  are  interbedded  with  unctu- 
ous schists,  and  rest  in  apparent  conformity  upon  a  great 
mass  of  vitreous  quartzite.  The  writer  has  since  exam- 
ined these  rocks  as  seen  on  ibe  Baraboo  River,  and  else- 
where, in  Wisconsin,  and  has  satisfied  himself  of  their 
identity  with  the  similar  rocks  previously  studied  by  him 
on  the  Atlantic  coast,  in  Pennsylvania,  in  Missouri,  and 
on  Lake  Superior.  Besides  the  details  respecting  these 
petrosilex  rocks  to  be  found  in  the  writer's  volume  on 
"Azoic  Rocks,"  pp.  189-195,  and,  again,  pp.  231-232, 
the  reader  is  referred  to  Essay  XL  in  this  present  vol- 
ume, §§  37-42,  for  a  fartlier  account  of  their  occurrence  in 
Pennsylvania.  The  general  high  inclination  both  of  this 
series  and  of  the  typical  Huronian,  renders  tlie  determina- 
tion of  their  thickness  difficult.  The  maximum  thick- 
ness of  the  Huronian  (excluding  the  petrosilex  or 
Arvonian  series)  to  the  south  of  Lake  Superior,  may, 
according  to  Brooks,  exceed  12,000  feet,  while  the  esti- 
mates of  Credner  and  Murray,  respectively,  for  this 
region,  and  for  the  north  shore  of  Lake  Huron,  are  20,000 
and  18,000  feet. 


^  il 


i    8 


,^^ 


IX.J 


PRE-CAAIBEIAN  liOCKS  m  NOKTH   AMvr 


ISra.  l.y  the  observutiou  o  '  ^.2? T  '=°"'''™<''''  "' 
"-hei-e  l,e  found  between  the  I  '^  ^'*  Biunxwick, 
-d  the  typical  Hu.-onira  trk  rihT  -"17''^^  ^'-'i' 
«  indicated  by  a  stratigraphtal  di^^'"'  '"'"'''"•  '^''"^ 
presence,  in  the  lower  part  o  tie  ,a  r'r'™'  "'"'  ''^  "'« 
oonglonierates  made  up  from  te  ,,  JT""'  "^  '=«»» 

pr  petiosilex  division      TirH  •  "^  "'"  «" Je,lyin„ 

-  "-"y  places,  ;  bbles  afd  T"'  """"'"  ^'""''"- 
P'eisses,  a  character  commortoH^*""';"'  "'  "■«  "Wer 
orystalline  series,  wiS  led  V  "'"^  ""  ^«"  >'™"Ser 
America  to  class  ;il  o  te  e  w  Tt  """'''  S-°^'^g^^t.\ 

The  Huronian   contain?  „  f"'""'""" ''""'''s- 

epidote,  hornblende  "and   pyro?"'"""'^  i""i-'«™  of 
varieties  of  diabasic  rocks    oft     "''„""''  '-^   """■'^'l  by 
-e  truly  stratified,  but  are'  not "Jt  ^^  n"""'"^'  ^''-h 
the  nontes  of  the  Norian  «.  '"'  """founded  with 

g*ro  is  „3o  frequtt,;;™:'   Th"'"^"  "^  --** 
•noreover,  includes  imperfect  i.'  •         ""'''""a"  series, 
»'te,.  serpentine,  and  Ste  Tf'T',  '"""•'^'"^«'  dolo- 
chlorrtic,  micaceouc,  and  ari  M,.  '"'''  '"'«*  "■""'"■ts  of 
to  be  identical  with  the  S-:::7  ^"^ists.    It  appears 
oi  the  Alps,  which  is  thfre  found      °''  S'-^^nstone  group 
the    ancient   gneisses    beW  «^  ,     """'^ '^'"■*'' •'"tweei 
gneisses  and  miea-schists    tL   ^  i"  ^"""^'^  '""'^^  of 
g'ven  at  length  in  Essay  x'"''^- °'  ""  ^^'"<''>  « 

%i'lst.t'i:!;'^''>^Ap-i:;."'  "'--^"^  '^« 

-ies  in  North°Amert:  ifnt?  hf "'"?  "  *'«■"»"'»  ' 

eontanrs  fine-grained  wirte  l5       '  ""'^  ^'  '^^<^  that  it 


mn 


it^tf 


tf 


>    ^S 


412 


THE    HISTOUY   OF   PllE-CAMBRIAN   ROCKS. 


[IX. 


other.  It  also  includes  hornblendic  gneisses  and  black 
hornblende-schists,  together  with  serpentine,  chrysolite- 
rocks,  diciiroite-gneiss,  and  crystalline  limestones.  The 
mica-schists  of  the  series  often  contain  garnets,  staurolite, 
andalusite,  fibrolite,  and  cyanite,  while  in  the  granitic 
veins  which  traverse  the  series  are  found  tourmaline, 
beryl,  and  cassiterite.  The  total  thickness  of  the  Montal- 
ban  is  apparently  much  greater  than  that  assigned  to  the 
Huronian,  upon  which  it  sometii^es  rests  unconformably, 
or,  in  the  absence  of  the  Huronian,  as  is  often  the  case, 
directly  upon  the  Laurentian. 

§  17.  As  we  are  here  following  not  the  stratigraphical 
succession  but  the  historic  development  of  our  knowledge 
of  the  American  pre-Cambrian  rocks,  we  return  to  a  con- 
sideration of  the  more  ancient  gneisses.  We  distinguish 
at  the  base  of  the  Eozoic  system  a  massive  and  essentially 
granitoid  gneiss,  with  little  or  no  mica.  To  this  funda- 
mental rock,  sometimes  called  the  Ottawa  gneiss,  and  of 
unknown  thickness,  succeeds  what  has  been  named  in 
Canada  the  Grenville  gneissic  series,  made  up  in  great 
part  of  a  gneiss  somewhat  similar  to  that  last  mentioned, 
with  intercalations  of  hornblendic  gneiss,  of  quartzite,  of 
pyroxenite,  of  serpentine,  of  magnetite,  and  of  crystalline 
limestones,  the  latter  often  magnesian,  occasionally  graph- 
itic, and  sometimes  attaining  thicknesses  of  a  thousand 
feet  or  more.  The  Grenville  series,  the  strata  of  which 
are  generally  highly  inclined,  has  an  aggregate  volume  of 
not  less  than  15,000  or  20,000  feet,  and  appears  to  rest 
unconformably  upon  the  fundamental  or  Ottawa  gneiss. 
This  gneissic  series,  with  its  intercalated  limestones,  some 
of  which  contain  Eozoon  Canadense^  was  the  typical 
Laurentian  of  Logan  and  Hunt,  named  by  them  in  1854, 
with  which  they  included,  at  that  time,  however,  not 
only  the  underlying  fundamental  gneiss,  but  an  upper 
granitoid  and  gneissoid  series,  composed  in  large  part  of 
plagioclase  feldspars,  chiefly  labradorite. 

§  18.   These  three  divisions  of  the  Eozoic  system  were 


'  >  ) 


IX.]         PRE-CAMimiAN   llOCKS  IN   NORTH   AMKUICA.       413 


I 


were 


thus  coMfouncled  under  the  common  name  of  Laurentian 
until,  in  1862,  tlie  hist  was  separated,  under  the  pro- 
visu)nal  name  of  Upper  Laurentian,  the  two  other  divis- 
ions united  being  called  Lower  Laurentian.  The  syno- 
nym of  Labradorian  was  subsequently,  for  a  time, 
employed  by  Logan  to  designate  the  upper  division,  until 
1870,  when  the  present  writer  proposed  for  it  the  name 
of  Norian,  retaining  that  of  Laurentian  for  the  two  lower 
divisions.  It  will  probably  be  found  desirable  to  separate 
the  typical  Laurentian  or  Grenville  series,  as  studied  and 
mapped  by  Logan,  Hunt,  and  Dawson,  from  the  less 
known  fundamental  or  Ottawa  gneiss,  and  to  make  of  this 
latter  a  distinct  group.  The  name  of  Middle  Laurentian, 
sometimes  given  to  the  typical  Laurentian,  loses  its  signi- 
ficance with  the  disappearance  of  that  of  Upper  Lauren- 
tian, now  replaced  by  Norian. 

The  Norian  series  is  made  up  in  great  part  of  granitoid 
or  gneissoid  rocks,  composed  essentially  of  plagioclase 
feldspars,  without  quartz,  but  with  a  little  pyroxene  or 
hypersthene,  often  with  titanic  iron-ore,  and  apparently 
identical  with  the  norites  of  Norway.  With  these  rocks 
are,  however,  found  alternations  of  gneiss  and  of  quartz- 
ite,  and  also  crystalline  limestones,  scarcely  different  from 
those  of  the  Laurentian.  We  therein  find  also  a  grani- 
toid rock  made  up  of  pink  orthoclase,  quartz,  and  bluish 
labradorite.  This  Norian  series  is  found  in  many  places 
covering  considerable  areas,  and  apparently  resting  in 
discordant  stratification  upon  the  typical  Laurentian.  Its 
thickness  has  been  estimated  at  over  10,000  feet. 

§  19.  Passing  now  above  the  younger  or  Montalban 
gneisses  and  mica-schists,  we  come  to  a  series  composed 
essentially  of  quartzites,  limestones,  and  micaceous  and 
argillaceous  schists.  The  quartzites,  occasionally  con- 
glomerate, are  sometimes  vitreous,  sometimes  granular, 
and  often  micaceous,  graduating  into  mica-schists  very 
distinct  from  those  of  the  Montalban.  The  mica  is  often 
damourite  or  sericite,  and  gives  rise  to  unctuous  glossy 


# 


l'^: 


ti 


I* 


414 


THK   HISTORY   OF  PRE-CAMBRIAN   ROCKS. 


[IX. 


|M 


I' 

r  t^  * 

f 


I   i 


)  I 


schists,  passing  into  argillites,  which  sometimes  contain  a 
feldspathic  admixture.  The  limestones  of  this  series, 
often  magnesian,  are  crystalline,  and  include  statuary 
marbles  and  cipolins.  We  find  in  the  schists,  which  are 
intercalated  alike  among  the  quartzites  and  the  lime- 
stones of  this  series,  masses  of  serpentine  and  of  ophical- 
cite,  and  occasionally  of  chloritic  and  hornblendic  min- 
erals, as  well  as  siderite,  magnetite,  and  hematite,  the 
iron-oxyds  being  often  mingled  with  the  quartzites. 
These  last  are  sometimes  flexible  and  elastic,  and  the 
whole  series  much  resembles  the  Itacolumitic  gi'oup  of 
Brazil.  It  has  a  thickness  in  different  parts  of  North 
America  of  from  4000  to  10,000  feet,  and  is  seen  lying 
unconformably  alike  upon  the  Laurentian,  the  Huronian, 
and  the  Alontalban.  There  are  found  in  the  quartzites  of 
this  series  tlie  imi)ressions  of  ScoUthtis,  and  in  the  lime- 
stones other  undetermined  forms.  This  is  the  Lower 
Taconic  series  of  the  late  Dr.  Emmons,  which  we  dis- 
tinguish by  the  name  of  Taconian.  Some  recent  writers 
have  by  mistake  confounced  it  with  the  Upper  Taconic 
of  the  same  author,  a  distinct  group,  which  Emmons 
declared  to  be  the  equivalent  of  the  Primordial  (Cambrian) 
of  Barrande,  and  which  is  the  original  or  unaltered  Quebec 
group  of  Logan. 

§  20.  The  Taconian  series  is  widely  spread  over  east- 
ern North  America,  to  the  eastward  of  the  great  paleozoic 
basin,  from  the  Gulf  of  St.  Lawrence  to  Alabama.  It  is 
also  found  in  an  area  to  the  north  of  Lake  Ontario,  in 
Hustings  County,  where  it  was  described  by  the  Canadian 
geological  survey  under  the  provisional  name  of  the 
Hastings  series,  and  is  represented  around  Lake  Superior 
by  what  has  been  called  the  Animikie  series.  This, 
though  early  recognized  as  Taconian  in  northern  Michi- 
gan, and  early  separated  by  Logan  from  the  Huronian  on 
the  north  shore  of  the  lake,  has  since  been  confounded 
with  it.  Much  that  in  the  northern  peninsula  of  Michi- 
gan, as  elsewhere,  has  been  called  Huronian,  is  Taconian. 


IX.] 


PRE-CAMBRIAN  ROCKS   IN   NOl  TH   AMEIIICA.       415 


Imau. 


The  latter,  the  writer  has  elsewhere  compared  with  a 
great  seri^  of  similar  schists  and  quartzites,  including 
serpentire,  anhydrite,  dolorute,  and  marbles,  greatly 
developed  in  nortliern  Italy,  wliere  it  overlies  the  younger 
gneisses  and  mica-schists,  and  has  been  by  various 
observers  successively  referred  to  the  mesozoic,  the  pale- 
ozoic, and  the  eozoic  periods.  A  full  account  of  tlie 
Taconian  series,  its  stratigraphical  relations,  and  its  dis- 
tribution in  North  America  and  elsewhere,  will-  be  found 
farther  on,  in  Essay  XL 

§  21.  The  Taconian  on  the  north  shore  of  Lake 
Superior  was  by  Logan  made  the  lower  division  of  his 
Upper  Copper-bearing  series,  which,  as  a  whole,  was  by 
him,  after  1862,  described  as  a  modification  of  wliat  lie 
then  called  the  Quebec  group.  The  upper  divi^non  of 
this  Copper-bearing  series,  rer.:arkable  for  its  native 
copper,  had  been  previously,  for  a  time,  confounded  by 
Logan  with  the  Huronian  itself,  while  by  otliers  it  was 
referred  to  the  Potsdam  period,  or  even  conjectured  to  be 
of  mesozoic  age.  The  geological  distinctness  of  tliis  great 
series  of  more  than  20,000  feet  of  strara  was,  however, 
finally  asserted  by  the  present  writer  in  1873,  when  he 
called  it  the  Keweenaw  group,  a  name  subsequently 
changed  by  him  to  Keweenian.  It  has  since  been  shown 
by  various  observers  that  the  fossiliferous  sandstones 
which  rest  in  horizontal  layers  upon  the  inclined  strata 
of  the  Keweenian,  belong  to  the  Cambrian,  and  hold  the 
fauna  of  the  Potsdam.  The  conglomerates  of  the  Ke- 
weenian cupriferous  series  contain  portions  alike  of  Lau- 
rentian,  Arvonian,  Huronian,  and  Montalban  rocks,  and 
overlie  the  schists  which  we  have  referred  to  the  Taco- 
nian. The  sandstones  and  argillites  of  the  Keweenian, 
which  are  interstratified  Avith  great  masses  of  melaphyre, 
are  uncrystalline.  It  remains  to  be  determined  whether 
the  intermediate  Keweenian  series  has  greater  affinities 
with  the  Taconian  than  with  the  Cambrian,  from  both  of 
which  it  is  distinct. 


416 


THE   HISTORY  OP  PltE-CAMBRIAN   UOCKS. 


[TX. 


We  have  thus  sought  to  include,  provisionally,  the  wliole 
vast  system  of  Primitive  and  Transition  crystalline  rocks, 
from  the  fundamental  granitoid  gneiss  upward,  under  the 
names  of  Laurentian,  Norian,  Arvonian,  Iluronian,  Mont- 
alban,  and  Taconian.  Certain  considerations  regarding 
the  distribution  and  the  stratigra[)hical  relations  of  these 
have  already  been  set  forth,  on  i)age  184,  to  vv^hich  the 
reader  is  referred. 


♦  t 


II. — PRE-CAMBRIAN   ROCKS   IN  EUROPE. 

§  22.  In  an  address  before  the  American  Association 
for  the  Advancement  of  Science,  in  1871,  in  which  the 
writer  maintained  the  Huronian  age  of  a  portion  of  the 
crystalline  schists  of  New  England  and  Quebec,  he  ex- 
pressed the  opinion,  based  in  part  upon  his  examinations 
at  Holyhead  in  1867,  and  in  part  upon  the  study  of  col- 
lections in  London,  that  certain  orystalline  schists  in 
North  Wales  would  be  found  to  belong  to  the  Huronian 
series.  The  rocks  in  question  were  by  Sedgwick,  in  1838, 
separated  from  the  base  of  the  Cambrian,  as  belonging  to 
an  older  series,  but  were  subsequently,  by  De  la  Beche, 
Murchison,  and  Ramsay,  described  and  mapped  as  altered 
Cambrian  strata  with  associated  intrusive  syenites  and 
feldspar-porphyries. 

§  23.  In  South  Wales,  at  St.  David's  in  Pembrokeshire, 
is  another  area  of  crystalline  rocks,  which  the  geological 
survey  of  Great  Britain  had  mapped  as  intrusive  syenite, 
granite,  and  felstone  (petrosilex-porphyry),  having  Cam- 
brian stratr,  converted  into  crystalline  schists  on  one  side, 
and  unaltered  fossiliferous  Cambrian  beds  on  the  other. 
So  long  ago  as  1864,  Messrs.  Hicks  and  Salter  were  led  to 
regard  ti.cse  granitoid  and  porphyritic  rocks  as  pre-Cam- 
brian,  and  in  1866  concluded  that  they  were  not  eruptive 
but  stratified  crystalline  or  metamorphic  rocks.  After 
farther  study.  Hicks,  in  connection  with  Harkness,  pub- 
lished, in  1867,  additional  proofs  of  the  bedded  character 
of    these    ancient    crystalline    rocks,  and    in    1877    the 


K  I 


IX.] 


PRE-CAMBUIAN   ROCKS    IN   EUIIOPE. 


first-named  observer  announced  the  conclusion  tluit 
they  belong  to  two  distinct  and  unconformable  series. 
Of  these,  the  older  consisted  of  the  granitoid  and  por- 
phyritic  felstone  rocks,  and  the  younger  of  greenish  crys- 
talline schists,  the  so-called  Altered  Cambrian  of  the 
official  geologists ;  both  of  these  being  overlaid  by  the 
undoubted  Lower  Cambrian  (Harlech  and  Menevian)  of 
the  region,  which  holds  their  ruins  in  its  conglomerates. 
To  the  lower  of  these  pre-Cambrian  groups.  Hicks  gave 
the  name  of  Dimetian,  and  to  the  up[)er  that  of  Pebidian. 
The  last,  with  a  measured  thickness  of  8000  feet,  he  sup- 
posed to  be  the  equivalent  of  the  Huronian,  and  com- 
pared the  Dimetian  with  the  Upper  Laurentian  of  Logan. 

The  Dimetian,  including  the  granitoid  and  gnei  '.c 
rocks  of  both  Norti)  and  South  Wales,  so  far  as  seen  oy 
the  writer  in  the  limited  outcro[)S,  resembles  the  Lauren- 
tian of  North  America.  It  was  by  a  misconception  that 
Hicks  provisionally  referred  the  Dimetian  to  the  Upper 
Laurentian,  —  a  name  at  one  time  used  by  the  geological 
survey  of  Canada  to  designate  the  Norian  series.  Hicks, 
at  the  same  time,  designated  as  Lower  Laurentian  the 
gneiss  of  the  Hebrides  (Lewisian  of  Murchison),  which 
he  believed  to  be  distinct  from  and  older  than  the  Dime- 
tian. These  two  may  correspond  to  the  Ottawa  and 
Grenville  divisions  of  the  proper  Laurentian  in  Canada. 

§  24.  The  similar  crystalline  rocks  of  North  Wales, 
already  noticed,  were  now  studied  by  Prof.  T.  McKenna 
Hughes,  of  Cambridge,  who  described  them  in  1878. 
These  include  in  Carnarvonshire  and  Anglesey  the  green- 
ish crystalline  schists  which  the  writer,  in  1871,  referred 
to  the  Huronian  (pre-Cambrian  of  Sedgwick,  and  Altered 
Cambrian  of  the  geological  survey),  certain  gi-anitoid 
rocks  formerly  described  as  intrusive  syenite,  and  also  a 
reddish  feldspar-porphyry  which  forms  two  great  ridges 
in  Carnarvonshire.  This  latter  was  by  Professor  Sedg- 
wick regarded  as  intrusive,  and  is,  moreover,  mapped  as 
such  by  the  geological  survey,  though  described  in  Ram- 


418 


THE   Ul«TOUV   OF  PBB-(;AMBRIAN  ROCKS. 


PX. 


say's  meiucir  on  the  geology  of  North  Wales  as  probably 
the  result  of  an  extreme  metamorphism  of  the  lower  beds 
of  the  Cambrian.  The  pre-Cambrian  age  of  all  tlieso 
rocks  was  clearly  shown  by  Hughes,  who,  however,  con- 
sidered that  tlie  whole  might  belong  to  one  great  strati- 
lijd  series;  wliile  Hicks,  from  an  examination  of  the  same 
region,  regarded  them  as  identical  with  the  Dimetian  and 
Pebidian  of  South  Wales. 

§  25.  Dr.  Hicks  continued  his  studies  in  both  of  these 
regions  in  1878,  —  being  at  times  accompanied  by  Dr. 
Toroll  of  Sweden,  Professor  Hughes  and  Mr.  Tawney  of 
Cambridge,  and  the  writer,  —and  was  led  to  conclude 
tl'.at,  besides  the  chloritic  schists  and  the  greenstones  of 
the  Pebidian  series,  and  the  older  granitoid  and  gneissic 
rocks,  there  exists,  both  in  North  and  South  Wales,  an- 
other independent  and  Intermediate  series,  to  which 
belongs  the  stratified  potrosilex  or  quartziferous  por- 
phyry already  noticed.  Tliis  is  sometimes  wanting  at 
the  base  of  the  Pebidian,  and  at  other  times  forms  masses 
some  thousands  of  feet  in  thickness.  At  one  locality, 
near  St.  David's?',  a  great  body  of  breccia  or  conglomerate, 
consisting  of  frrgments  of  the  petrosilex  united  by  a 
crystalline  dioritic  cement,  forms  the  base  of  the  Pebid- 
ian. For  this  intermediate  series,  which  constitutes  the 
quartziferous  porphyry-ridges  of  Carnarvonshire,  Hicks 
and  his  friends  then  proposed  the  name  of  Arvonian, 
from  Arvonia,  the  Roman  name  of  the  region. 

§  26.  This  important  conclusion  was  announced  by 
Dr.  Hicks  at  the  meeting  of  the  British  Association  for 
the  Advancement  of  Science,  at  Dublin,  in  August,  1878. 
The  writer,  previous  to  attending  this  meeting,  had  the 
good  fortune  to  examine  these  various  pre-Cambrian 
rocks  in  parts  of  Carnarvonshire  and  Anglesey  with 
Messrs.  Hicks,  Torell,  and  Tawney.  He  subsequently, 
in  company  with  Hicks,  visited  the  region  in  South 
Wales  where  these  older  rocks  had  been  studied,  and 
was  enabled  to  satisfy  himself  of  the  correctness  both  of 


I?:.  J 


rillMIAMniMAX    KOCKS    I  .V    KUUOl'E. 


410 


by 

for 

878. 

the 


the  observations  and  conclusions  of  Tlickd,  and  of  the 
complete  parallelism  in  8tratigra[)liy  and  in  mineral  com- 
position between  these  pre-Cambrian  rocks  on  the  two 
sides  of  tlie  Atlantic.  It  may  hero  be  mentioned  that 
Torell,  who,  during  his  visit  to  America  in  187G,  had  an 
opl)ortunity  of  studying,  with  the  writer,  the  potrosUexes 
of  New  England  and  Peinisylvania,  —  which  he  regarded 
as  identical  with  the  hiilleflinta  of  Sweden,  —  at  once 
recognized  them  in  the  Arvonian  series  of  North  Wales. 
Of  the  many  areas  of  these  various  prc-Cambrian  rocks 
which  the  writer  was  enabled  to  examine  in  company 
■with  Hicks,  may  be  mentioned  the  granitoid  mass  of  Twt 
Hill  in  the  town  of  Carnarvon,  and  the  succeeding 
Arvonian  to  Port  Dinorwic,  followed,  across  the  ^Nlenai 
Strait,  by  the  Pebidian  on  the  island  of  Anglesey,  near 
the  Menai  bridge.  Farther  on,  the  Pebidian  was  again 
met  with,  near  the  railway  station  of  Ty  Croes,  in  the 
southwest  part  of  the  island,  succeeded  by  a  large  body 
of  Arvonian  petrosilex,  and  a  ridge  of  gronitoid  gneiss, 
fragments  of  which  make  up  a  breccia  at  the  base  of  the 
Arvonian  series.  The  Pebidian  is  again  well  displayed  at 
Holyhead. 

§  27.  In  South  "Wales,  the  similar  rocks  -were  exam- 
ined by  him  at  St.  David's,  where  three  small  bands  or 
veins  of  an  impure,  coarsely  crystalline  limestone  are 
included  in  the  Dimetian  granitoid  rock,  which  is  here 
often  exceedingly  quartzose.  It  may  be  remarked  that 
the  Dimetian,  as  originally  defined  at  this,  its  first  recog- 
nized locality,  included  a  great  mass  of  Arvonian  petro- 
silex, the  two  forming  a  ridge  which  extends  for  some 
miles  in  a  northeast  direction,  flanked  by  Pebidian  rocks, 
which  are  sometimes  in  contact  with  the  one  and  some- 
times with  the  other  series.  At  Clegyr  Bridge  was  seen 
the  base  of  the  Pebidian,  already  mentioned  as  consisting 
of  a  conglomerate  of  Arvonian  fragments.  Another  belt 
of  the  same  crystalline  rocks  was  also  visited,  a  few  miles 
to  the  eastward  of  the  last,  and  not  far  from  Haverford- 


420 


THi:    IIISTOUY   OF   rUE-CAMimiAN   HOOKS. 


lix. 


I   !i- 


west,  forming,  according  to  Hicks,  a  ridge  several  miles 
in  lenjith  and  about  a  mile  wide.  Where  seen  at  Ilocii 
Castle,  it  was  found  to  consist  of  Arvonian  petrosilex, 
with  some  gianitoid  rock  near  by.  The  ridge  is  Hanked 
on  the  northwest  side  by  Pebidian  and  Cambrian,  and 
on  the  soutiieast  by  Silurian  strata,  let  down  by  a 
fault. 

§  28.  On  the  shore  of  Llyn  Padarn,  near  the  foot  of 
Snowdon,  in  North  Wales,  the  jiorphyritic  petrosilex  of  the 
Arvonian  is  again  well  displayed,  while  in  contact  with  it, 
and  at  the  base  of  the  Llanberis  (Lower  Cambrian)  slates, 
is  a  conglomerate  made  up  almost  wholly  of  the  petro- 
silex. This  locality  was  supposed  by  Kamsay  and  others 
to  show  that  the  petrosilex  is  the  result  of  a  metamor- 
phosis of  the  lower  portion  of  the  Cambrian,  the  conglom- 
erates being  regarded  as  beds  of  passage.  The  writer, 
after  a  careful  examination  of  the  locality,  agrees  with 
Messrs.  Hicks,  Hughes,  and  Bonney  that  there  is  no 
ground  for  such  an  opinion,  but  that  the  conglomerate 
marks  the  base  of  the  Cambrian,  which  here  reposes  on 
Arvonian  rocks,  and  is  chiefly  made  up  of  their  ruins.  In 
like  manner,  according  to  Hughes,  the  Cambrian  in  othet 
parts  of  this  region  includes  beds  made  of  the  dShris  of 
adjacent  granitoid  rocks. 

§  29.  These  petrosilex  conglomerates  of  Llyn  Padarn 
are  indistinguishable  from  those  found  at  Marblehead  and 
other  localities  near  Boston,  Massachusetts,  which  have 
been  in  like  manner  interpreted  as  evidences  of  the  sec- 
ondary origin  of  the  adjacent  petrosilex  beds,  into  whicn 
they  have  been  supposed  to  graduate.  Tlie  writer  has, 
however,  always  held,  in  opposition  to  this  view,  that 
these  conglomerates  are  really  newer  rocks,  made  up  of 
the  ruins  of  the  ancient  petrosilex.  He  has  found  simi- 
lar petrosilex  conglomerates  at  various  points  on  the 
Atlantic  coast  of  New  Brunswick,  of  Lower  Cambrian, 
Silurian,  and  Lower  Carboniferous  ages,  all  of  which  have, 
in  their  turn,  been  by  others  regarded  as  formed  by  the; 


:,-i 


ni 


IX.] 


rUE-CAMnUIAX   HOCKS   IN    EUUOT'K. 


421 


of 


of 


the 


alteration  of  strata  of  thcso  geological  periods.  Tho 
cvideijco  now  furnislicd  in  South  WuIoh  of  still  older 
(Iluronian)  beds  of  i)otro.siU;x  conglonierato  sliould  be 
noted  by  students  of  North  American  geology.  From 
observations  near  Doston,  made  by  one  of  my  former 
students,  I  liavo  for  some  time  suspected  the  exist- 
ence of  petrosilcx  conglomerates  of  pre-Cambrian  age. 

§  30.  To  the  eastward  of  the  localities  already  men- 
tioned in  Wales,  are  some  other  small  ureas  of  crystalline 
rocks,  including  those  of  the  Malverns,  and  tho  Wrekin 
and  other  hills  in  Shropshire,  all  of  which  appear  as 
islands  among  Cambrian  strata ;  also  those  of  Charnwood 
Forest,  in  Leicestershire,  which  rise  in  like  manner 
among  Triassic  rocks.  Tho  Wrekin,  regarded  by  ]Mur- 
chison  as  a  post-Cambrian  intrusion,  has  been  shown  by 
Callaway  to  bo  unconformably  overlaid  by  Lower  Cam- 
brian strata,  and  consists  in  part  of  bedded  greenstones, 
and  in  part  of  banded  reddish  i^etrosilex-porphyries, 
closely  resembling  tho  Arvonian  of  North  AVales  and  the 
corresponding  rocks  of  North  America.  Tho  geology  of 
Charnwood  has  within  tin  past  two  years  been  carefully 
studied  by  Messrs.  Hill  and  Bouncy.  The  ancient  rocks 
of  this  region  are  in  part  crystalline  schists  (embracing, 
in  the  opinion  of  Hicks  and  of  the  writer,  —  who  have 
seen  collections  of  them,  —  representatives  both  oi!  the 
Pebidian  and  the  Arvonian  of  Wales)  and  in  part  erup- 
tive masses,  including  the  granitic  rocks  of  Mount 
Sorrel. 

§  31.  The  crystalline  schists  of  Charnwood  offer,  as 
was  pointed  out  by  Messrs.  Hill  and  Bonney,  many  resem- 
blances with  parts  of  the  Ardennian  series  of  Dumont  in 
France  and  Belgium.  These,  which  have  been  in  turn 
regarded  as  altered  Devonian,  Silurian,  and  Lower  Cam- 
brian, were,  as  shown  by  Gosselet,  islands  of  crystalline 
rock  in  the  Devonian  sea,  and  in  one  part  include  argil- 
lites  with  impressions  of  Oldhamia  and  an  undetermined 
graptolite.      These  rocks  have  lately  been  described  in 


>4i! 


n 


'm 


ii 


422 


THE  HISTOPwY  OF  niE-CAMBRIAN  ROCKS. 


[IX. 


I    5 


^^l 


.i  (' 


■M 


iM<.' 


detail  in  the  admirable  memoir  of  De  la  Valine  Poussin 
and  Renard.  The  writer  had  the  good  fortune,  in  1878,  to 
visit  this  region,  and,  in  company  with  Gosselet  and 
Renard,  to  examine  the  section  along  the  valley  of  the 
Meuse.  The  crystalline  rocks  here  displayed  greatly 
resemble  those  of  the  American  Huronian,  in  which  may 
be  found  most  of  the  types  described  by  the  authors  of 
the  memoir  just  mentioned.* 

§  32.  Hicks,  in  a  paper  on  the  Classification  of  the 
British  Pre-Cambrian  Rocks,  which  is  published  in  the 
Geological  Magazine  for  October,  1879,  concludes  that 
the  Pebidian  is  "  a  group  of  enormous  thickness,  which  is 
largely  distributed  over  Great  Britain,  where  it  has  a  pre- 
vailing strike  of  N.N.E.  and  S.S.W.,  or  from  this  to  N.E. 
and  S.W."     In  addition  to  the  localities  which  we  have 

*  The  following  is  a  partial  list  of  recent  publications  regarding 
these  rocks,  as  discussed  in  §§  23-32,  to  the  close  of  IST'J.  For  their  later 
history,  see  farther  on.  Essay  XI.,  §§  189-193. 

In  the  Quar.  Jour.  Geol.  Sec.  of  London  are  the  following  papers  on 
these  rocks  in  Wales:  Hicks,  May,  1877,  p.  230;  Il'cks  &  Davies,  February, 
1878,  p.  147,  and  May,  1878,  p.  153;  Iluglies  &  Bonney,  February,  1878, 
p.  137;  Hicks  &  Davies,  May,  1879,  p.  285;  Ilicks  &  Bonney,  ihid., 
p.  205;  Bonney,  ibid.,  p.  309;  Bonney  &  Houghton,  ibid.,  p.  821;  Hughes, 
November,  1879,  p.  082;  Maw,  August,  1878,  p.  704.  Also  Hicks,  Rocks 
of  Ross-shire,  November,  1878,  p.  811;  Tawney,  Older  Rocks  pf  St.  David's: 
Proc.  Bristol  Naturalists'  Society,  vol.  ii.,  part  2,  p.  110. 

On  these  rocks  in  Shropshire,  Quar.  Joui'.  Geol.  Soc,  Allport,  August, 
1877,  p.  449;  Callaway,  November,  1877,  p.  653,  and  August,  1878,  p.  754; 
Callaway  &  Bonney,  November,  1879,  p.  043.  On  these  rocks  in  Cham- 
wood  Forest,  in  the  same  journal,  Hill  &  Bonney,  November,  1877,  p.  753, 
and  May,  1878,  p.  199.  See  farther.  Hunt,  Chemical  and  Geological 
Essays,  pp.  34,  209,  270,  272,  278,  283;  also  his  Azoic  Rocks  (Second 
Geol.  Survey  of  Penn.,  1878),  pp.  187,  188. 

For  the  rocks  of  the  Ardennes,  see  Mgmoire  sur  los  Roches  dites  Plu- 
toniques,  etc.  (4to,  pp.  264),  by  De  la  Valine  Poussin  and  Ifenard,  from 
Memoiresdel'Acad.  Royalede  la  Belgique  for  1870 :  Mt'moire  surlaComp. 
Min^ralogique  du  Coticule,  by  Renard,  from  the  same  for  1S77;  and  The 
Mineralogical  and  Microscopical  Characters  of  the  Belgian  Whetstones, 
by  Renaid,  Monthly  Microscopical  Journal  for  1877.  vol.  xvii.,  p.  209. 
Also  Gosselet  and  Malaise,  Terrain  Silurien  des  Ardennes,  Bull.  Acad. 
Roy.  de  la  Belgique  (2),  No.  7,  1808;  Dewalque,  Terrain  Cambrieii  des 
Ardennes,  Ann.  Soc.  G^ol.  de  la  Belgique,  torn.  I.,  p.  03;  and  farther, 
Hunt,  Chem.  and  Geol.  Essays,  p.  270. 


IX.l 


PRE-CAMBRIAN   ROCKS  IN   EUROPE. 


423 


already  mentioned  in  Great  Britain,  he  notes  its  occur- 
rence in  Shropshire  and  in  Charnwood  Forest,  and  also  in 
the  nortliwest  of  Scotland,  where,  as  elsewhere,  it  enters 
largely  into  the  Lower  Cambrian  conglomerptes.  The 
group  is  concisely  described  by  him  as  consisting,  "for  the 
most  part,  of  chloritic,  talcose,  feldspathic,  and  micaceous 
schistose  rocks,  alternating  with  slaty  and  massive  green- 
stones, dolomitic  limestones,  serpentines,  lava-flows,  por- 
cellanites,  breccias,  and  conglomerates.  It  is  also  traversed 
frequently  by  dikes  of  granite,  dolerite,  etc." 

§  33.  There  is  not,  so  far  as  yet  known,  in  any  of  the 
British  localities  especially  mentioned,  any  representative 
either  of  the  Taconian  or  the  Montalban  series.  The 
presence  of  rocks  having  the  characters  of  the  Huronian 
was,  however,  indicated  as  having  been  observed  by  me 
in  various  parts  of  Perthshire  and  Argyleshire,  and  also 
on  Lough  Foyle,  in  L*eland,  where  I  have  observed  the 
Montalban  well  displayed  in  the  Dublin  and  Wicklow 
Hills,  and  pointed  out  the  probable  presence  of  both 
Huronian  and  Montalban  in  specimens  of  rocks  from 
Donegal.  To  the  latter  series  I  also  referred,  from  similar 
evidence,  in  1871,  certain  crystalline  schists  from  the  Scot- 
tish Highlands,  where  the  typical  Pebidian  of  Hicks, 
previously  designated  by  me  as  Huronian,  is  also  largely 
displayed. 

Hicks  has  since  found  there  a  series  of  crystalline  strata 
which  succeed  the  Pebidian,  and  which  he  has  called 
Upper  Pebidian.  These,  as  they  are  the  predominant 
rocks  in  the  Grampian  Hills,  he  proposed  to  name  the 
Grampian  series.  The}''  consist  in  great  part  of  tender 
gneisses  or  granulites,  with  mica-schists,  and,  as  I  have 
elsewhei-e  pointed  out,  have  all  the  characters  of  the  Mont- 
alban or  younger  gneiss  series,  as  seen  alike  in  North 
America  and  in  the  Alps.  The  conclusion  from  all  the 
observation  of  Hicks  and  Callaway  up  to  1882,  as  then 
stated  by  me,  was  that  "  the  crystalline  strata  of  the  Scot- 
tish Highlands,  regarded  by  the  geological  survey  of  Great 


424 


THE   HlSTOllY   OF   PllE-OAMIUlIAN   HOCKS. 


[IX. 


1^ 


f' 


,r 


*    ,1 


Britain  as  altered  paleozoic;  strata,  include  representatives 
of  various  pre-Cambrian  groups,  including  Montalban 
(Grampian),  Huronian  (Pebidian),  and  Arvonian,  to 
which  group  Hicks  refers  the  petrosilex  st  ies  found  in 
Glencoe."  * 

§  34.  For  an  account  of  more  recent  investigations  in 
these  crystalline  rocks  of  the  Scottish  Highlands,  the 
reader  is  referred  to  Essay  XI.,  §§  190-193.  In  this  essay, 
which  discusses  the  Taconian,  and  its  relations  alike  to 
newer  and  to  older  oeries,  will  be  found  much  on  the 
various  divisions  of  Eozoic  rocks.  Therein  is  noticed  the 
recent  attempt  of  Dana  to  resuscitate  the  long  abandoned 
views  of  Nuttall  and  Mather  as  to  the  paleozoic  age 
of  a  great  area  of  crystalline  rocks,  principally  Laurentian, 
in  Westchester  County,  New  York.  The  veinstones  of 
these  ancient  crystalline  rocks,  and  especially  of  the 
Laurentian  series,  have  been  described  at  length,  ante, 
pages  223-238.  An  account  of  the  pre-Cambrian  rocks 
of  the  Alps  and  the  Apennines  will  be  found  farther  on, 
in  part  iv.  of  Essay  X. 

§  35.  In  closing  this  historical  sketch,  mention  should 
be  made  of  the  stateniv^ents  put  forth,  in  1879,  by  A.  R.  C. 
Selwyn,  director  of  the  geological  survey  of  Canada,  in 
his  report  of  progress  for  1877-78  (p.  14  A),  in  which  he 
sought  to  set  aside  the  whole  of  the  preceding  classifica- 
tion of  Eozoic  rocks.  He  then  proposed  to  unite  in  one 
group,  under  the  name  of  Huronian,  not  only  the  rocks 
around  Lakes  Superior  and  Huron,  to  which  this  name 
was  originally  give  ,  and  the  crystalline  belt  in  the  prov- 
ince of  Quebec  (which  I  had  already,  in  1871,  called 
Huronian),  but  the  whole  o*^  the  Upper  Copper-bearing 
series  of  Lake  Superior,  thus  embracing  both  the  Taco- 
nian, or  lower  'division  of  the  latter,  and  the  Kewee- 
nian.  Not  content  with  this,  he  would  farther  include  in 
the  Huronian  the  "Templeton,  Buckingham,  Grenville, 
and  llawdon  crystalline  limestone  series,"  which  is  the 

*  Progress  of  Geology,  Smithsoniau  Report  for  1S82. 


/. 


IX] 


PEE-CAMBRIAN  KOCKS  IN  EUROPE. 


425 


Grenville  gneissic  series  of  Logan  and  myself,  and  also 
the  "  Upper  Laurentian  or  Norian."  He  moreover  added 
to  these  the  Hastings  limestone  series,  which  he  supposed 
might  be  an  equivalent  of  the  Grenville  series.  The  Mont- 
alban  and  the  Arvonian  were  overlooked  in  his  scheme, 
but  with  these  exceptions  the  Huronian,  as  imagined  by 
Selwyn,  was  made  to  include  every  known  grouD  of 
strata,  whether  crystalline  or  uncrystalline,  from  the  base 
of  the  fossiliferous  Cambrian  to  what  he  designated  as 
"those  clearly  lower  unconformable  granitoid  or  syenitic 
gneisses  "  which  contain  no  bands  of  calcareous  or  other 
extraneous  rock;  and  which  may  be  supposed  to  corre- 
spond to  that  basal  division  described  above  as  the  Ottawa 
gneiss.  The  whole  of  the  vast  succeeding  series  of  16,000 
feet  of  granitoid  gneisses,  with  quartzites,  crj'stalline  lime- 
stones, etc.,  which  had  been  studied  during  thirty  years 
by  Logan,  Murray,  and  myself,  and  constituted,  with  the 
Norian,  the  Laurentian  system  as  originally  defined  and 
named  in  1854,  was  thus  to  be  confounded,  under  one 
name,  with  the  widely  different  series  to  which  the  desig- 
nation of  Huronian  had  been  given  in  1855,  and  with  the 
entire  Upper  Copper-bearing  series  of  Logan,  embracing 
alike  the  Taconian  and  the  Keweenian.  It  may  be  pre- 
sumed that  longer  study  and  larger  opportunities  of 
observation  will  lead  Mr.  Selwyn  to  conclusions  more  in 
harmony  with  those  of  his  predecessors. 

Appendix. 

The  whetstone  or  coticule  of  the  Ardennes,  named  on  page  422, 
consists,  according  to  the  chemical  and  microscopical  studies  of  Kenard, 
of  rounded  grains  or  minute  ciystals  of  manganese-alumina  garnet 
(spessartine),  with  others  of  green  tourmaline  and  probably  of  chryso- 
beryl,  included  in  a  damourite-like  mica,  sometimes  with  pyrophyllite  in 
fissures,  and  with  intersecting  veins  of  quartz.  Layers  of  this  aggregate 
from  one  to  ten  centimetres  thick,  pale  yellow  in  color,  conchoidal  in 
fracture,  and  with  density  3.22,  are  interstratified  with,  and  graduate 
into,  a  fine-grained  schist  or  phyllade,  itself  with  transverse  cleavage, 
made  up  chiefly  of  similar  micas,  but  contalnin^i  besides  the  garnets,  etc., 
plates  of  heuiatite,  and  carbonaceous  grains.  The  evidence  of  contempo- 
raneous formation  of  these  various  species  is  clear,  and  illustrates  well 
the  crenltic  process. 


4 


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i     I 


X. 

THE  GEOLOGICAL.  HISTORY  OF  SERPENTINES,  WITH 
STUDIES  OF  PRE-CAMBRIAN  ROCKS. 

This  essay  wat  presented  to  tlie  Royal  Society  of  Canada,  May  23,  1883,  and 
printed  under  its  present  title  in  the  first  volume  of  thvi  Transactions  of  the  Society. 

I. — HISTORICAL  INTRODUCTION. 

§  1.  Few  questions  in  geology  are  involved  in  greater 
obscurity  or  more  contradiction  than  the  history  of  ser- 
pentine. As  a  preliminary  to  a  discussion  of  certain 
observations  by  myself  and  others  thereon,  it  seems,  there- 
fore, desirable  to  recall  some  passages  in  this  Instory, 
which  nivay  serve  to  show  the  differences  of  opinion  now 
existing,  and,  it  is  hoped,  prepare  the  way  for  their  recon- 
ciliation. These  differences  may  be  considered  under  two 
heads,  namely :  the  geognosy  of  serpentine,  or  its  relation 
to  the  other  rosks  of  the  earth's  crust ;  and  the  geogeny, 
or  the  origin  and  mode  of  formation  of  serpentine,  the 
mineralogical  relations  of  which  are  discussed  on  page  333. 

Setting  aside  for  the  moment  the  question  of  the  occur- 
rence of  serpentine  as  an  accidental  mineral  disseminated 
in  calcareous  rocks,  and  considering  only  its  occurrence 
in  rock-masses,  either  pure  or  mingled  with  other  silicates, 
the  first  question  which  presents  itself  is  whether  such 
massive  serpentines  are  contemporaneous  with  the  enclos- 
ing rocks,  or  whether  they  have  been  subsequently  in- 
truded among  these, — in  other  words,  whether  serpentines 
are  indigenous  or  exotic  rocks. 

§  2.  We  find  at  the  beginning  of  our  century  that  the 
most  competent  ol>servers  were  agreed  in  regarding  ser- 
pentines as  stratified  contemporaneous  deposits  in  the  so- 
called  primary  rocks.     Patrin  described  those  of  Mont 

426 


^■]       THE   GEOLOGICAL  HISTORY  OF  SERPENTINES.        427 


Rose  and  of  the  Rothhorn  as  interstratified  with  calcare- 
ous and  micaceous  schists,  while  Saussure  found  those  of 
Mont  Cerviu  to  present  similar  conditions,  and  described 
certain  serpentines,  found  near  Genoa,  as  alternating  with 
bands  of  calcareous,  quartzose,  and  micaceous  schists  or 
argillites.  Humboldt,  in  like  manner,  noticed  the  strati- 
fied character  of  the  serpentines  near  Bareith,  and  Jameson 
found  those  of  Rothsay,  in  Scotland,  to  be  interstratified 
with  micaceous  and  talcose  schists,  and  with  crystallii;e 
limestone,  in  repeated  alternations,  of  which  he  gives  a 
diagram,  mentioning,  l.owever,  as  an  opinion  held  by 
some,  that  the  masses  both  of  serpentine  and  of  limestone 
"  form  great  veius  rather  than  vertical  sheets."  He  else- 
where describes  serpentine  as  a  primitive  stratified  rock, 
contemporaneous,  and  alternating  with  crystalline  schists.* 

§  3.  A  little  later  we  find,  in  1826,  jNIacculloch,  in  his 
"Geological  Classification  of  Rocks,"  separating  the  prim- 
itive rocks  into  two  groups,  stratified  and  unstratified, 
the  latter  consisting  of  granite  and  serpentine.  He  as- 
signed as  a  reason  for  placing  serpentine  in  the  latter 
class  that  it  does  not  appear  to  be  decidedly  stratified, 
but,  at  the  same  time,  remarks  that,  unlike  other  unstrati- 
fied rocks,  as  granite  or  t'-ap,  he  had  not  found  serpen- 
tines to  present  ramifying-  veins.  Subsequent  studies  in 
the  Shetland  Isles  led  him  .o  make  what  he  calls  "  an  im- 
portant correction  "  in  its  history,  in  the  Apiiendix  to  the 
volu'^'ie  just  named,  where  he  ainiounces  his  conclusion 
that  tiie  serpentines  are  stratified  rocks,  like  gneiss  or 
mica-schists,  adding  a  revised  tabular  view,  in  which  they 
are  included  with  these  in  the  stratified  division  of  the 
primitive  vocks,  granite  alone  being  retained  in  the  un- 
stratified division.! 

§  4.  Boase,  in  his  "  Primary  Geology,"  in  1834,  de- 
scribes the  serpentines  of  Cornwall  as  associated  with  tal- 

*  See,  for  the  text  of  the  above  references,  the  quotations  in  .'   nker- 
ton's  Petral'jgy,  1821,  i.,  334-343  ;  ii.,  COS-612. 
t  Macculloch,  loc.  cit.,  pp.  78,  243,  052-655. 


•US 


«'r 


428       THE  GEOLOGICAL   HISTORY  OF  SERPENTINES.         [X. 

cose  and  cliloritic  and  actinolite-schists,  and  what  had 
been  "  called  hornblende-slate,"  to  which  the  serpentine 
seemed  in  some  instances  subordinated.  He  farther  com- 
pares these  associations  and  modes  of  occurrences  with 
those  described  by  MaccuUoch.*  De  la  Beche,  in  like 
manner,  in  his  "  Geology  of  Cornwall  and  Devon,"  notes 
the  seeming  passage  of  the  serpentine  into  the  hornblende- 
.  tte  in  man}'  places,  but  also  its  apparent  "intrusion 
an  id  the  latter  with  force";  a  seeming  contradiction, 
which  he  recognizes,  but  endeavors  to  explain.f 

§  5.  Unlike  MaccuUoch  and  Boase,  De  la  Beche  re- 
garded serpentine  as  nn  eruptive  rock  of  posterior  origin 
to  the  associated  schists,  agreeing  in  this  with  Brongniart, 
who  had  placed  serpentine  among  pliitonic  rocks.  A 
similar  view  was  held  b}^  Elie  de  Beaumont  |  and  by  Savi, 
and,  without  entering  into  farther  details,  we  may  notice 
that  they  have  been  followed  by  Sismondl,  Lory,  and 
others,  who  maintain  the  plutonic  origin  of  the  Alpine 
serpentines,  while,  on  the  other  hand,  Scipion  Gras, 
Gastaldi,  Favie,  and  Stapff  regard  them  as  of  aqueous  and 
sedimentary  origin.  The  views  of  the  present  school  of 
Italian  geologists,  as  well  as  Dieulefait  and  Lotti,  will  be 
noticed  in  part  vi.  of  this  essay. 

§  6.  In  the  United  States,  we  find  Edward  Hitchcock, 
in  1841,  reviewing  the  opinions  of  MaccuUoch,  Brongniart, 
De  la  Beche,  and  others,  and  deciding  that  the  serpentines 
of  Massachusetts  are  to  be  regarded  as  stratified  rocks. § 
Emmons,  in  1842,  after  noticing  the  conclusions  of  Hitch- 
cock as  to  serpentine,  regarded  it,  nevertheless,  as  an  un- 
stratified  rock,  but  distinguished  it  from  trappean  rocks, 

*  Boase,  loc.  cit.,  p.  46. 

t  De  la  Beche,  loc.  cit.,  pp.  .35,  09.  ^ 

t  After  discussing  the  question  with  Elie  de  Beaumont,  in  1855,  I 
asked  his  eminent  colleague,  De  Senarmont,  as  to  the  eruptive  origin  of 
serpentines.  He  replied  that  his  own  extended  studies  of  the  serpentines 
of  Europe  had  led  him  to  reject  as  wholly  untenable  the  theory  of  their 
plutonic  character. 

§  Geology  of  Massachusetts,  II.,  616, 


X.]  THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.      429 


inasmuch  as,  according  to  him,  it  is  never  found  in  injected 
veins  or  dikes.*  Later,  however,  in  1855,  he  separated  it 
from  so-called  pyroplastic  rocks,  like  "  basalt,  trap,  and 
greenstone,"  and  included  it  in  lioth  divisions  of  his  pyro- 
crystalline  class:  that  is  to  say,  (1)  as  laminated  serpen- 
tine, with  gneiss,  micaceous,  talcose,  and  hornblendic 
slates  and  limestone ;  and  (2)  as  massive  serpentine,  with 
granite,  syenite,  etc.f 

§  7.  J.  D.  Whitney,  in  1851,  included  hornblende  and 
serpentine  rocks,  together  with  the  magnetic  and  specular 
oxyds  of  iron,  under  the  title  of  "  Igneous,"  and  the  sub- 
title of  "  Trappean  and  Volcanic  Rocks."  J  Henry  D. 
Rogers,  in  1858,  described  the  steatite  belt  on  the  Schuyl- 
kill River,  in  Pennsylvania,  as  formed  from  the  mica- 
schists  of  the  region  through  impregnation  from  "  the  dike 
of  serpentine  ^yhicll  everywhere  adjoins  it,"  thus  implying 
the  posterior  origin  and  eruptive  character  of  the  latter. 
Elsewhere  he  describes  the  cr^-stalline  rocks  of  the  same 
region  as  including  "true  injected  serpentines."  He, 
however,  looked  on  veins  of  quartz  and  epidote,  and  even 
of  carbonate  of  lime,  as  also  of  eruptive  o''  gin.§  Lieber, 
at  the  same  time,  in  his  report  on  the  geology  of  South 
Carolina,  regarded  not  only  the  serpentines  of  that  region, 
but  the  associated  steatite  and  actinolite  rocks,  as  erup- 
tive masses. 

§  8.  In  opposition  to  these  plutonic  views,  the  geologi- 
cal survey  of  Canada,  from  an  early  date  (1848),  insisted 
upon  the  stratified  character  of  the  serpentines  found  in 
the  northern  extension  of  the  Green  Mountain  range  in 
eastern  Canada.  They  were  shown  to  be  accompanied  by 
hornblendic,  steatitic,  dioritic,  and  other  schistose  rocks,  as 
well  as  by  dolomites  and  magnesites.     The  writer,  in  dis- 


*  Geology  of  Kew  York,  Northern  District,  pp.  67-70. 
t  American  Geology,  I.,  43. 
t  Geology  of  Lake  Superior,  II.,  2. 

§  Geology  of  Pennsylvania,  vol.  I.,  passim.    See  also  the  author, 
in  Azoic  Bocks,  pp.  15-19. 


411 


430     THE  GEOLOGICAL  HISTORY  OP  SERPENTINES.  [X. 

cussing  the  relations  of  tliese  in  1863,  announced  "  the 
conclusion  that  the  whole  series  of  rocks  .  .  .  from 
diorites,  diallages,  and  serpentines,  to  talcs,  chlorites,  and 
epidosites,  have  been  formed  under  similar  conditions," 
and  were  aqueous  deposits.* 

§  9.  Here  it  will  be  seen  that  we  approach  the  second 
question  mentioned  in  §  1,  namely,  that  of  the  origin  and 
mode  of  formation  of  serpentines,  which,  in  the  view  of 
t^  3  wlio  maintain  its  indigenous  character,  is,  of  course, 
«;  sely  connected  with  the  problem  of  the  origin  of  its 
.1,  lated  crystalline  rocks.  The  notions  of  the  earlier 
;;^fcolo,"'  ' s  with  regard  to  this  latter  problem  were, in  most 
cases,  \tiry  vague,  some  of  them  holding  the  view,  still 
taught  in  our  own  day  by  H(3bert,  that  these  rocks,  includ- 
ing gneisses,  micaceous,  chloritic,  and  hornblendic  schists, 
were  all  formed  by  some  unexplained  process  during  the 
cooling  of  the  globe,  without  the  intervention  of  water.f 
With  few  exceptions,  however,  they  admitted,  with  Wer- 
ner, the  aqueous  origin  of  tliese,  whether  holding,  with 
De  la  Beche  and  with  Daubree,  that  they  were  deposited 
successively  from  the  highly  heated  waters  of  a  primeval 
sea,J  or  the  more  commonly  received  view,  that  the  sedi- 
ments were  laid  down  under  conditions  of  temperature 
not  unlike  those  of  the  present  time,  and  were  afterwards 
the  subject  of  internal  change  (diagenesii),  or  of  indefinite 
replacement  and  substitution  (metasomatosis). 

§  10.  The  latter  doctrine,  which,  in  the  hands  of  some 
of  its  disciples,  has  found  an  extension  limited  only  by 
their  imaginations,  was  at  once  applied  to  explain  the 
origin  of  serpentine.  Silicated  rocks  destitute  of  magne- 
sia, and  carbonated  rocks  destitute  of  silica  could  alike,  it 
was  maintained,  be  converted  into  serpentine,  which  was 

*  Geology  of  Canada,  p.  612.  See  also  the  author's  Contrihutions  to 
the  History  of  Ophiolites,  1858,  Amer.  Jour.  Sci.,  xxv.,  217-226,  and 
xxvi.,  234-240. 

t  Bull.  Soc.  Geol.  de  France,  1882,  xi.,  30,  and  ante,  p.  85. 

t  Chemical  and  Geological  Essays,  p.  301,  and  ante,  pp.  104-106. 


!  ^ 


11^^ 


[X. 


X.1  THE   GEOLOGICAL   HISTORY   OF   SERPENTINES.      431 

held  to  be  tlie  last  term  in  the  metasoniatic  changes  of  a 
vast  number  of  mineral  species.  Hence,  it  was  no  longer 
necessary  to  supi)ose  the  direct  deposition  of  a  magnesir<'> 
sediment,  or  an  eruption  of  an  igneous  magnesiun  rock,  tc 
explain  the  presence  of  contemporaneous  or  of  inject 
serpentines.  The  legitimate  outcome  of  this  hypothesis  is 
found  in  tlie  teaching  of  Delesse,  in  1858  (when  he  yet 
held  the  eruptive  nature  of  serpentine,  which  he  classed 
with  other  "  trappean  rocks"),  —  namely,  tliat  "granitic 
and-  trappean  rocks "  may,  in  certain  cases,  be  changed 
into  a  magnesian  silicate,  which  may  be  serpentine,  talc, 
chlorite,  or  saponite.* 

§  11.  I  have  elsewhere  shown  ^  ow  Delesse,  three  years 
later,  abandoned  alike  the  met.  on  ic  hypothesis  and 
the  notion  of  the  eruptive  ori  'in  r  ^he  serpentines,  in 
favor  of  that  view  which  I  ]  \0  puc  forth  in  1859  and 
1860,  that  the  serpentines  wc'e  ■' imdoubtedly  indigenous 
rocks,  resulting  from  the  aUera.xOn  of  silico-magnesian 
sediments."  At  the  same  '  e,  is  a  concession  to  those 
who  maintained  the  occurrence  of  eruptive  serpentines,  it 
was  said  that  "  the  final  result  of  heat,  aided  by  water,  on 
silicated  rocks  would  be  their  softening,  and  in  certain 
cases  their  extravasation  as  plutonic  rocks,"  which  were 
to  be  regarded  as  "  in  all  cases  altered  and  displaced  sedi- 
ments." t  Later,  in  re-stating  this  point  in  1880,  it  was 
said,  "  The  eruptive  rocks,  or,  at  least,  a  large  portion  of 
them,  are  softened  and  displaced  portions  of  ancient  nep- 
tunian  rocks,  of  which  they  retain  many  of  the  mineralogi- 
cal  and  lithological  characters."  $  The  proviso  contained 
in  the  last  sentence  is  explained  by  the  view  since  main- 
tained at  length,  in  Essays  V.  and  VI.  in  this  volume,  that 
the  rocks  of  the  basaltic  and  doleritic  tyjjcs  are  portions 
of  an  original  igneous  mass,  which  antedated  the  appear- 
ance of  liquid  water  at  the  surface  of  the  globe. 

*  Ann.  des  Mines  (5),  xii.,  509,  and  xiiL,  393,  415. 

t  Chem.  and  Geol.  Essays,  pp.  316-318. 

t  Amer.  Jour.  Science,  xix.,  270,  and  ante,  p.  126. 


t 

:  fit] 


:i 


r  ■  'Vi. 


m 


\'''.i 


432      THE  GEOLOlilCAL   IIISTOUY   OF   SERPENTINES.  PC- 

§  12.  After  careful  stiuliea,  alike  in  the  field  and  in  the 
laboratory,  I  was  led,  in  18(50,  to  maintain  that  the  origin 
of  serpentine  and  related  niagnesian  rooks  was  to  be  found 
in  deposits  of  liydrous  silicates,  like  the  magnesian  marls 
of  the  Paris  basin ;  and  in  1861  we  not  only  find  Delesse 
teaching  this  doctrine  of  the  origin  of  these  rocks  from 
the  alteration,  or  so-called  metamorphism,  of  such  magne- 
sian precipitates,  but  declaring,  in  the  spirit  of  my  teach- 
ing, as  above,  that  "  the  plutonic  rocks  are  formed  from 
the  metamorphic  rocks  and  represent  the  maximum  of 
intensity,  or  tiie  extreme  term  of  general  metamorphism."* 
The  history  of  the  abandonment  by  Delesse  of  his  former 
view  of  the  plutonic  for  that  of  the  neptunian  origin  of 
serpentines,  and  his  acceptance  at  the  same  time  of  the 
liyi)othesis  of  an  aqueous  origin  of  plutonic  rooks,  is  sig- 
nificant as  a  recognition  of  the  new  ideas  for  which  I  had 
contended,  and  which  constitute  a  new  departure  in  theo- 
retical geogeny.  See,  farther,  on  this  point,  a  note  to  §  116, 
by  Dieulefait.f 

§  13.  In  farther  explanation  of  this  source  of  magne- 
sian silicates,  it  was  shown  by  the  writer,  in  a  series  of 
experiments  the  results  of  which  were  published  in  1865, 
that  whenever  the  comparatively  soluble  silicates  of 
alkalies  or  of  lime  (which  are  set  free  by  the  decay  of 
crystalline  silicates,  and  are  found  in  many  natural 
waters)  are  brought  in  contact  with  solutions,  like  sea- 

*  Delesse,  fitudes  sur  le  Metamorpliisme,  1861,  p.  87. 

t  The  testimony  of  Sclpion  Gras,  in  1854,  in  his  learned  memoir,  "  Sur 
le  Terrain  Anthraxiffere  des  Alpes"  (Ann.  des  Mines  ['>],  v.,  473-602), 
against  the  igneous  hypothesis,  should  here  be  recorded.  Of  the  seipen- 
tlnes,  euphotides,  variolites,  and  so-called  spilites,  of  the  Alps,  having 
said  that  they  are  either  eruptive  or  rocks  altered  in  place,  he  adds:  "  We 
have  long  since  adopted  this  latter  hypothesis,  which  alone  appears  to  us 
to  be  'n  accordance  with  observation.  It  is  not  uncommon  to  see  these 
so-called  plutonic  rocks  of  the  Alps  offer  a  distinct  stratification,  the 
appearances  of  which  are  exactly  like  those  of  adjacent  sediments.  This 
is  especially  true  for  the  spilites  and  the  serpentines,  the  epigenir;  origin 
of  which  isevident."  (Loc.  cit.,  p.  601.)  This  epigenic  hypothesis  involved 
a  metamorphosis  of  sediments  by  heat  and  moisture,  apparently  not  iinlike 
that  mentioned  farther  on,  in  §  111. 


I'-r 


i.  :^ ; 


X.]  THE  GEOLOGICAL  HISTORY  OF  SEIIPENTINES.     433 


water,  lioldiiig  iiingnesian  sulphnte  or  clilorul,  cloublo 
decomposition  takes  place,  with  the  sei)aration  of  a  very 
insoliibki  gelatinous  silicate  of  magnesia;  and  farther, 
that  preciiiiaited  silicate  of  lime  is  decomposed  by  diges- 
tion with  such  nnignesian  solutions,  its  lime  becoming 
partially  or  wholly  replaced  by  magnesia. 

Tlup  process,  it  was  pointed  out,  is  the  reverse  of  tliat 
which  happens  when  carbonates  of  alkalies  or  of  mag- 
nesia come  in  contact  with  sea-water,  in  which  case  the 
comparative  insolubility  of  carbonate  of  lime  causes  ilie 
decomposition  of  the  soluble  calcium-salts  present.  "In 
the  one  case,  the  lime  is  separated  as  carbonate,  the  mag- 
nesia remaining  in  solution ;  while  in  the  other,  by  the 
action  of  silicate  of  soda  (or  of  lime),  the  magnesia  is 
removed,  and  the  lime  remains.  Ilcnce  carbonate  of 
lime  and  silicates  of  magnesia  are  found  abundantly  in 
nature,  while  carbonate  of  magnesia  and  silicates  of  lime 
are  produced  only  under  local  and  exceptional  conditions. 
It  is  evident  that  the  production  from  the  waters  of  the 
early  seas  of  beds  oP  sepiolite,  talc,  serpentine,  and  other 
rocks,  in  which  a  magnesian  silicate  abounds,  must,  in 
closed  basins,  have  given  rise  to  waters  in  which  chlorid 
of  calcium  would  predominate."  *  The  generation  of 
magnesian  silicates  in  aqueous  sediments  was  thus  shown 
to  be  the  result  of  a  natural  process  as  simple  as  that 
giving  rise  to  carbonate  of  lime. 

§  14.  There  are  many  questions  connected  with  this 
theory  of  the  source  of  serpentine  and  related  rocks,  such 
as  the  probable  variations  in  the  composition  of  the  origi- 
nal silicates ;  their  admixture  with  other  silicates  and 
carbonates ;  the  changes  wrought  in  these  by  subsequent 
chemical  reactions,  resulting  in  the  genesis  of  talc,  ser- 
pentine, enstatite,  and  olivine,  and,  in  certain  cases,  the 
subsequent  changes  of  these  anhydrous  species ;  the  pres- 
ence, in  these  magnesian  minerals,  of  ferrous  silicate,  which 
is  so  abundant  in  many  serpentines,  and  its  relations  to 
*  Amer.  Jour.  Sci.  (2),  xl.,  49  ;  also,  Chem.  and  Geol.  Essays,  p.  123. 


nm 


!  ■  M ! 


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i 


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434      THE  GEOLOGICAL    HISTOnY   OF  SEItPENTINES. 


PC 


the  problem  t)f  tlio  ori<^lii  of  glaiiconitc,  itself  sometimes  a 
more  or  less  magnesiiiii  siliciite;  finally,  the  notable  fact 
of  the  prcseiico  in  most  of  these  magnesian  rocks  of  small 
portions  of  the  rarer  metals,  such  as  nickel  and  chromium, 
which  is  to  be  considered  in  connection  with  the  similar 
metallic  inii)rognation  of  certain  mineral  waters  that  may 
well  liave  intervened  in  the  production  of  these  magnesian 
silicates.  All  of  these  are  important  points,  which  must 
be  reserved  for  future  discussion.  [Some  of  these  have 
.since  been  considered,  in  connection  with  the  question  of 
glauconite,  om  pages  19G-198.] 

§  15.  One  great  object  in  geology  is  to  discover  by 
what  natural  processes  the  different  chemical  elements 
liave  been  segregated  and  combined  during  successive  ages 
in  the  forms  in  which  we  now  find  ihem  in  the  earth's 
crust ;  in  other  words,  how  from  a  once  homogeneous 
mass  have  been  separated  quartz,  corundum,  bauxite,  car- 
bonates of  calcium  and  magnesium,  as  well  as  carbonates, 
oxyds,  and  sulphids  of  manganese,  iron,  zinc,  copper,  and 
other  metals.  Not  less  important  is  the  problem  of  the 
genesis  of  the  corresponding  protoxyd-silicates,  and  espe- 
cially of  those  of  calcium,  magnesium,  and  iron,  Avhich 
form,  often  with  little  or  no  admixture,  considerable 
masses  in  the  earth's  crust.  Of  these,  it  is  unnecessary 
to  say,  the  magnesian  rocks  under  consideration  constitute 
an  important  part,  and  all  analogies  lead  to  the  conclu- 
sion that  their  constituent  elements  have  been  brought 
together  by  aqueous  processes,  such  as  we  have  already 
indicated. 

n.  —  SERPENTINES  IN  NORTH  AJFERICA. 

§  16.  It  is  evident  that  if  we  once  come  to  regard  ser- 
pentine as  a  rock  formed  from  aqueous  sediments  of 
chemical  origin,  there  is  no  reason,  a  priori,  why  it  may 
not  be  found,  like  limestone,  dolomite,  or  gypsum,  inter- 
calated in  stratified  deposits  at  different  geological  hori- 
zons, and  with  different  lithological  associations.    Several 


X.1 


SERrENTINEa   IN   NOUTIT   AMERICA. 


485 


such  horizons  of  serpentine  have  been  observed  in  North 
America,  which  will  bo  noticed  in  ascending  order. 

Included  in  the  ancient  gneissic  series  to  which  the 
name  of  Laurentian  has  been  given,  serpentine  is  fre- 
quently met  with,  associated  alike  with  crystalline  lime- 
stone and  with  dolomite.  In  these,  Mie  serpentine  is 
often  disseminated  in  grains  or  small  irregular  masses, 
giving  rise  to  varieties  of  so-called  ophicalcite.  These 
imbedded  masses  of  serpentine  are  sometimes  concretion- 
ary in  aspect,  and  may  have  a  nucleus  of  white  granular 
pyroxene.  They  often  recall,  in  their  arrangen.ent,  im- 
bedded chert  or  flint,  and,  like  it,  sometimes  attain  large 
dimensions.  These  berpentines  occasionally  include  the 
calcareous  skeletons  of  Eozodn  Canadense,  the  silicate 
replacing  the  soft  parts  of  the  organism,  as  described  by 
Dawson  and  Carpenter.  Occasionally,  the  serpentines  of 
this  horizon  form  beds  of  considerable  size,  either  pure  or 
mingled  only  with  small  portions  of  calcite  or  dolomite. 
Of  these,  many  instances  are  seen  with  the  limestone^  of 
the  Laurentifin  in  Canada,  and  a  remarkable  example 
occurs  at  New  Rochelle,  on  Long  Island  Sound,  near 
New  Yoi'k  city,  where  massive  bedded  serpentine,  highly 
inclined,  and  interstratified  with  crystalline  limestone, 
often  itself  mingled  with  serpentine,  occupies  a  breadth 
of  about  400  feet  across  the  strike,  the  whole  being  con- 
formably interstratified  with  massive  gneisses  and  black 
hornblendic  rocks  with  red  garnet.*  The  general  charac- 
ters of  the  serpentines  found  with  the  Laurentian  lime- 
stones have  been  elsewhere  described  by  the  present 
writer.f  Their  lower  specific  gravity,  and  generally  paler 
colors,  together  with  a  larger   proportion   of  combined 

*  For  an  account  of  this  locality,  see  Mather,  Geo)  F-irst  District  of 
New  York  ( 1842),  p.  462;  also  J,  D.  Dana,  Amer.  Jour.  Sci.  (3),  xx.,  30-32. 

t  For  descriptions  and  analyses,  by  the  t  uthor,  of  Laurentian  serpen- 
tines, see  Geol.  Canada,  1863,  pp.  471,  591 ;  also  Contributions  to  the 
History  of  Ophiolites  (1858),  Amer.  Jour.  Sci.  (2),  xxvi.,  pp.  234-2.S6, 
239.  Much  of  this  so-called  serpentine  belongs  to  the  species  retinalite, 
ante,  p.  332. 


.itL. 


436      THE   GEOLOGICAL  HISTOEY  OF   SERPENTINES.  CX. 

water,  serve,  in  some  cases  at  least,  to  distinguish  the 
serpentines  of  this  horizon  from  those  to  be  mentioned 
as  occurring  in  the  Huronian  series.  To  this  may  be 
added  a  smaller  amount  of  combined  iron-oxyd,  and,  in 
most  cases,  the  absence  of  compounds  of  nickel  and 
chrome,  which  are  almost  invariably  present  in  the  latter. 
This  distinction  is  probably  not  absolute,  since  chromite 
is  said  to  occur  in  the  serpentine  of  New  Rochelle,  and  a 
chroraiferous  garnet  has  been  found  in  the  Laurentian 
rocks  in  Canada. 

§  17.  The  serpentines  next  to  be  noticed  occur  in  very 
different  lithological  associations  from  the  last,  and  in  a 
group  of  rocks  which  has  been  described  under  the  name 
of  Huronian.  These  may  be  defined  as  in  large  part 
greenish  hornblendic  schistose  rocks,  passing,  on  the  one 
hand,  into  massive  greenstones,  diorites,  or  euphotides, 
and,  on  the  other  hand,  into  steatitic,  chloritic,  and  hy- 
dromicaceous,  or  so-called  tulcose  or  nacreous  schists, 
some  varieties  of  which  resemble  ordinary  argillites,  with 
quartzose  layers,  ofton  with  epidote,  and  with  associated 
beds  of  ferriferous  dolomite  and  magnesite.  In  this  litho- 
logical group  (already  referred  to,  in  §  8),  which  is  now 
known  to  mark  a  definite  geological  horizon,  the  serpen- 
tines are  found  interbedded,  sometimes  mingled  with  car- 
bonate of  lime  or  of  magnesia,  but  seldom  or  never 
presenting  varieties  like  the  granular  ophicalcite  of  the 
Laurentian.  To  this  horizon  belong  the  serpentines  of 
eastern  Canada,  found  in  the  continuation  of  the  Green 
Mountain  range,  as  well  as  those  of  Newport,  Rhode  Island, 
and  apparently  those  of  Cornwall,  Anglesey,  and  Ayrshire, 
in  Great  Britain.  The  serpentines  of  this  series  are  darker 
colored  than  the  last,  and  generally  contain  small  portions 
of  chrome  and  nickel  in  combination,  the  former  in  part 
as  chromite.* 


\^ 


<'  \ 


*  For  an  account  of  these  serpertires,  see  Geology  of  Canada,  1863, 
pp.  472,  ''()«~612  ;  also  Contributions  to  the  History  of  Ophiolites  (1858), 
Amer.  Jour.  Sci.  (2),  xxv.,  217-226. 


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be 
I,  in 
and 
tter. 
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name 
!  part 
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id  hy- 
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s,  with 
Dciated 

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ith  car- 
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Island, 

yrsiiire, 
e  darker 
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in  part 


nada,  1863, 
lites  (1858), 


X.) 


SERPENTINES  IN  NOETH  AMERICA. 


437 


§  18.  Serpentines  are  also  met  with  in  eastern  North 
America  in  somewhat  different  associations  from  the  two 
foregoing  groups,  and  apparently  belonging  to  a  third 
geological  horizon.  The  determination  of  the  precise 
stratigraphical  relations  of  the  serpentines  in  question 
presents,  however,  certain  difficulties,  ai'ising  from  consid- 
erations which  will  be  made  apparent  in  the  sequel.  Ser- 
pentine, though  not  exempt  from  sub-aerial  decay,  resistif 
this  process  better  than  hornblendic,  feldspathic,  and  cal- 
careous rocks.  Hence  it  happens  that  in  regions  Avhere 
these  are  decomposed  and  disintegrated  to  considerable 
depths,  associated  masses  of  serpentine  may  be  found 
rising  out  of  the  soil,  without  any  evidences  of  the  pre- 
cise nature  of  the  rocks  which  once  enclosed  them.  Illus- 
trations of  this  condition  of  things  are  found  in  the 
vicinity  of  Westchester  and  of  Media,  in  Chester  County, 
Pennsylvania.  The  underlying  rocks  in  this  region  are 
known  to  be  chiefly  gneisses,  with  hornblendic  and  mica- 
schists,  and  include  what  are  believed  to  belong  to  two 
distinct  series,  both  of  which  are  well  displayed  in  the 
section  seen  on  the  Schuylkill  River,  below  Norristown. 
Here  the  older  Laurentian  gneiss,  such  as  it  appears  in 
the  South  Mountain  and  the  Welsh  Mountain,  comes  up 
in  Buck  Ridge,  while  the  newer  gneiss  and  mica-schist 
series  is  seen  succeeding  it  to  the  southward,  at  Mana- 
yunk  and  Chestnut  Hill,  at  which  latter  locality  it  also 
appears  on  the  north  side  of  the  narrow  Laurentian  belt. 
In  this  section,  as  it  is  exposed  on  the  Schuylkill,  a  belt 
of  serpentine,  Avith  steatitic  and  chloritic  rocks,  appears 
between  the  two  series,  but  elsewhere  it  is  wanting  along 
the  outcrop  of  the  older  gneiss.  In  tho  localities  farther 
west  in  Chester  County,  alreadj^  mentioned,  at  West- 
chester and  Media,  where  the  rocks  adjacent  to  the  ser- 
pentine are  disintegrated,  and  have  disappeared  from 
decay,  it  cannot  be  determined  whether  these  serpentine 
masses  belong  to  the  older  or  the  newer  series  —  which 
latter  appears  to  be  similar  to  that  including  "the  serpen- 


fl 


-^TT 


mim 


438      THE  GEOLOGICAL  HISTORY   OF  SERPENTINES.  [X. 

tine  and  chrysolite  rocks  of  Mitchell  County,  North  Caro- 
lina.    (§  123.) 

§  19.  The  serpentine  of  Brinton's  quarry,  near  West- 
chester, Fenns^ivania,  is  distinctly  bedded,  granular,  and 
often  finely  laminated,  with  disseminated  scales  of  a  mica- 
ceous mineral,  giving  it  a  gneissoid  structure  and  aspect. 
A  black  schistose  hornbleudic  rock,  with  red  garnet,  is 
said  to  have  been  found  in  an  excavation  adjoining  the 
serpentine,  pnd  fragments  gathered  in  the  vicinity  showed 
thin  interlaininations  of  black  hornblende  with  greenish 
serpentine.  TIk  dip  of  the  strata,  of  which  several  hun- 
dred fee'  ;iie  here  exposed,  s  to  the  northwest,  at  a  high 
angle,  approaching  the  vertical.  They  are  traversed, 
nearly  at  right  angl'^s,  by  a  vertical  granitic  vein,  which 
has  been  traced  for  many  hundred  feet  in  a  northwest 
course.  This  vein,  wliich  is  generally  from  three  to  six 
feet  in  breadth,  is  white  in  color,  and  in  parts  may  be 
described  as  a  fine-grained  binary  granite,  the  feldspar  of 
which  is  superficially  kaoliuized.  In  other  parts,  it  be- 
comes very  coarse-grained,  presenting  large  cleavage- 
forms  of  orthoclase.  A  banded  or  zoned  structure,  parallel 
to  the  well  defined  A\'alls,  is  observed  in  some  parts,  and 
in  one  case  a  lenticular  mass  of  white  vitreous  quartz 
occupies  tlie  centre.  This  veinstone,  which  carries  black 
tourmaline,  and  is  said  to  have  afforded  beryl,  has  all  the 
characters  of  the  ordinary  endogenous  granitic  veins 
found  in  the  gneissic  rocks  of  the  Appalachians,  which 
veins  I  have  elsewhere  described  in  detail.* 

§  20.  The  rocks  in  the  vicinity  of  the  serpentine  near 
Westchester  are,  as  already  said,  deeply  decayed,  but 
wherever  seen  in  cuttings  are  found  to  be  mica-schist  and 
micaceous  gneiss.  Such  rocks,  with  a  northwest  dip, 
appear  to  underlie,  at  no  gi'cat  distance,  the  mass  of  ser- 
pentine exposed  at  Stroud's  Mill.  Similar  rocks  are  also 
found  on  the  railroad  between  Westchester  and  Media, 

*  Amer.  Jour.  Science  (3),  i.,  182-187,  and  Chem.  and  Geol.  Essays, 
pp.  192-200,  also  ante,  p.  223, 


X.] 


SEIIPENTINES  IN  NOllTH  AMERICA. 


439 


Geol.  Easays, 


where  tliey  are  exposed  in  a  cutting  nea^*  the  latter 
station,  about  a  mile  from  which  is  found  a  great  outcrop 
of  distinctly  stratified  serpentine,  resembling  that  of 
Brinton's  quarry,  and  with  a  steep  northwest  dip.  It 
includes  an  iuterstratified  mass,  about  twenty  feet  thick, 
of  a  fine-grained  reddish  gneissoid  rock,  approaching 
leptynite  or  granulite  in  character,  divided  into  distinct 
beds,  generally  from  four  to  eight  inches  in  thickness, 
between  which  are  sometimes  found  layers  of  a  few 
inches  of  a  soft  serpentine,  and,  in  one  case,  of  a  broadly 
fcliated  green  chloritic  mineral.  Considerable  differences 
in  texture  and  aspect  were  observed  between  tlie  serpen- 
tine beds  below  and  those  above  this  quartzo-feldspatliic 
mass,  which  is  indigenous,  tand  not  to  be  confounded  witli 
the  endogenous  transversal  mass  described  at  Brinton's 
quarry.  In  the  study  of  these  rocks  near  Westchester,  I 
was  much  aided  by  Dr.  Persifor  Frazer,  who  kindly 
accompanied  me,  and,  from  his  previous  labors  in  the 
geological  survey  of  the  district,  was  familiar  with  its 
details. 

§  21.  Serpentine  rocks  also  occur  on  Manhattan  Island, 
in  the  city  of  New  York,  where  they  are  still  exposed 
between  Fifty-seventh  and  Sixtieth  Streets,  west  of  Tenth 
Avenue,  and  are  directly  iuterstratified  in  gneissic  and 
micaceous  rocks,  which  may  either  belong  to  the  older 
gneiss  series  of  the  Highlands,  or  to  a  newer  group. 
Associated  with  the  massive  serpentine  of  this  locality 
are  found  small  quantities  of  a  granular  ophicalcite,  and 
near  it  is  a  mass  of  anthopyllite  rock.  This  locality  was 
long  since  described  by  Dr.  Gale,  when  the  rocks  were 
more  fully  exposed  than  at  present.* 

§  22.  Serpentine  masses  are  also  found  in  the  vicinity 
of  the  last,  on  Staten  Island,  and  at  Iloboken,  in  both  of 
which  localities  the  encasing  gneisses,  seen  in  New  York 
city,  are  wanting,  and  the  serpentine  api)ears  along  the 
eastern  margin  of  the  triassic  belt  of  the  region.     The 

*  Mather,  Geology  of  the  Southern  District  of  New  York,  p.  401. 


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440      THE  GEOLOGICAL  HISTORY  OF   SERPEINTINES.  [X. 

serpentine  of  Staten  Island  is  of  much  interest,  as  it 
presents  many  features  which  would  seem  at  first  sight  to 
lend  support  to  the  view  of  its  igneous  origin.  The 
serpentine  rocks  here  occupy  an  area  of  a  little  over  thir- 
teen square  miles  in  the  northern  half  of  the  island,  and 
form  a  ridge,  presenting  a  succession  of  rounded  hills, 
from  a  mile  and  a  half  to  two  miles  or  more  in  width, 
fcxtending  in  a  northeast  and  southwest  course,  with  an 
average  height  of  200  feet,  but  rising  in  one  part  to  420 
feet  above  the  sea.  Along  the  western  base  cf  this  ridge 
lie  the  red  sandstones  of  the  trias,  but  the  contact  of 
these  with  the  serpentine  is  concealed  beneath  the  soil. 
A  long  ridge  of  diabase  rock,  similar  to  tliut  which  pene- 
trates the  trias  on  the  west  bank  of  the  Hudson,  runs 
through  the  sandstones  for  a  length  of  nearly  six  miles, 
nearly  parallel  to  the  serpentine  belt,  and  ai  a  distance  of 
from  half  a  mile  to  a  mile.  Along  tlie  sontiieru  and  east- 
ern borders  of  tiie  serpentine  are  spread  horizontal  cre- 
taceous clays,  partially  overlaid  by  ilrift,  while  on  the 
north  side  of  the  island,  where  tlip  serj)eiitine  hills  rise 
abruptly  at  a  little  distance  from  the  shore,  arc  the  only 
known  outcrops  of  other  rocks;  one,  a  ledge  of  anthophyl- 
lite  rock  like  that  .."conjianying  the  serpentine  in  New 
York  c'ty,  and  jt.oIIu  ■ ,  a  few  hundi'cd  feet  distant  from 
the  latter,  and  fr^ui  tue  serpentine,  consisting  of  a  coarse 
pegmatite,  having  all  the  aspect  of  an  ordinary  concre- 
tionary granitic  vein,  and  containing  besides  ^^'ystals  of 
orthoclase,  sometimes  twelve  inches  in  length,  small  por- 
tions of  a  white  triclinic  felds])ar,  and  rare  cr3'3tals  of  red 
garnet.  A  second,  smaller  outcrop  of  a  similar  kind  is 
found  near  by.  These  granitic  and  anthophyllite  rocks 
appear  from  beneath  the  water  and  the  sands  of  the 
beach. 

§  23.  Such  an  occurrence  of  serpentine,  rising  from 
out  of  the  nearly  horizontal  and  low-lying  mesozoic  strata 
of  tlie  island,  was  well  calculated  to  sustain  the  notion  of 
the  e  aptive  nature  of  this  rock  which  was  put  forth  by 


[X. 


of 

by 


X.] 


SERPENTINES   IN  NORTH  AMERICA. 


441 


Mather  in  liis  description  of  this  locality.  He,  in  his 
report,  above  cited,  included  the  serpentine  in  his  "  Trap- 
pean  Division,"  in  the  same  category  with  the  adjacent 
eruptive  mesozoic  diabase,  regarding  the  serpentine  "  as 
due  to  the  action  of  the  same  general  causes,  modified 
in  a  manner  unknown  to  us."  * 

The  history  of  this  area  of  serpentine  becomes  intelli- 
gible when  studied  in  the  light  of  the  facts  already  men- 
tioned above.  It  was  apparently,  in  triassic  time,  a  range 
of  hills  left  by  the  disintegration  of  the  adjacent  gneiss, 
the  lower-lying  surfaces  of  whicl;  are  concealed  beneath 
the  ne  '.'ji'  sediments  of  the  region.  Since  that  time,  as  I 
have  elsewhere  pointed  out,t  the  serpentine  itself  has 
undergone  a  process  of  sub-aerial  change,  as  is  evident  by 
the  layer  of  deca^-ed  ma:ter,  with  included  masses  of 
limonite,  which,  in  tliose  portions  that  have  escaped  ero- 
sion, still  covers  the  serpentine  to  the  depth  of  tei.  or 
twelve  feet  (ante^  p.  2G8).  For  many  of  the  above  'letailw 
of  this  region,  I  have  availed  myself  of  a  description  of 
its  geology,  witli  map  and  sections,  published  in  1880,  by 
Dr.  N.  L.  Britton,$  of  the  School  of  Mines,  Coiumbin. 
College,  New  York,  with  whom  I  had,  in  1883,  the  aiivni- 
tage  of  visiting  this  interesting  locality,  and  to  w-  ,m  I 
desire  to  make  my  grateful  acknowledgments  for  valuable 
information  respecting  it. 

§  24.  The  serpentine  rock  which  seen  at  Castle  Ilill, 
Hoboken,  on  the  west  bank  of  the  '  ,dson,  opposite  New 
York  city,  is  believed  by  Dr.  Brittoii  to  be  a  continuation 
of  that  of  Staten  Island,  and,  like  ,i,  lies  on  the  eastern 
border  of  the  trias  ;  while  the  soriientine  outcrop  on  the 
west  side  of  New  York  city  h  x  strike  which  v/ould 
carry  it  to  the  east  of  Staten  Island,  and  probably  corre- 
sponds to  a  repetition  of  the  same  belt.   Gneissic  rocks  are 

*  Loc.  cit.,  p.  283.  [For  a  farther  notice  of  this  serpentine,  seepos^, 
Essay  XL,  §  178.] 

t  Amer.  Jour.  Science  (3),  xxvi.,  206, 

X  Tlie  Geology  of  Kiclunoml  County  (Staten  Island),  N.  Y.,  Ann. 
New  York  Academy  of  Sciences,  Vol.  II.,  N  ,  'i. 


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442      THE  GEOLOGICAL   HISTOllY  OF   SERPENTINES.  [X. 

met  with  in  a  boring  near  the  serpentine  at  Hoboken,  and 
are  found  in  the  small  islands  between  Manhattan  and 
Staten  Islands,  so  that  there  can  be  no  reasonable  doubt 
that  the  serpentines  of  Staten  Island  and  of  Hoboken  be- 
long, like  that  of  New  York  city,  to  the  gneissic  series  of 
the  region.  The  determination  of  the  precise  relations 
of  these  gneissic  rocks  to  those  accompanying  the  serpen- 
tines of  eastern  Pennsylvania,  already  described,  remains 
for  farther  inquiry.     See  Essay  XL,  §  187. 

§  25.  We  have  next  to  notice  the  occurrence,  in  Penn- 
sylvania, of  serpentine  in  the  Lower  Taconic  rocks  of 
Emmons,  the  Primal  slates  of  Rogers,  which  he  supposed 
to  belong  to  the  horizon  of  the  Potsdam  of  the  New  York 
series.  In  accordance  with  this  view,  we  find  that  in  a 
report  by  Genth  on  the  mineralogy  of  Pennsylvania,  in 
1875,  the  occurrence  of  serpentine  is  mentioned,  though 
without  any  details,  in  the  "Potsdam  sandstone"  near 
Bethlehem,  at  the  iron  mines  of  Cornwall,  and  also  in  the 
township  of  Warwick,  Chester  County.*  This  statement 
is,  however,  misleading,  inasmuch  as  the  serpentine  is  not 
found  in  the  sandstone  which  has  been  conjectured  to  be 
the  equivalent  of  the  New  York  Potsdam,  but  in  certain 
schists  and  limestones,  which  have  been  referred  to  that 
geological  horizon,  —  namely,  the  so-called  Primal  slates. 
The  history  of  these  is  given  at  length  in  Essay  XL 

§  26.  I  have  had  an  opportunity  of  observing  the 
occurrence  of  serpentine  at  Cornwall,  where  it  forms  small, 
irregular  masses  disseminated  in  a  bed  of  crystalline 
limestone,  itself  subordinate  to  the  great  mass  of  crystal- 
line schists  which  include  tiio  magnetite  largely  mined  at 
this  locality.  Serpentia^,  generally  with  limestone,  is 
found  at  many  other  looaUties  associated  with  iron-ores  at 
the  same  geological  horizon,  as  at  Fritz's  Island  and  else- 
where near  Reading,  at  Boyerstown,  and  at  the  Jones 
iron  mine,  near  to  Warwick,  where  it  is  found  in  small, 
lenticular  masses   imbedded   directly   in    the   crystalline 

*  Second  Geological  Survey  of  Penn.,  Report  B,  p.  115. 


-'  'fe'-i'-i^ 


aw 


SEIUENTINES   IN  NORTH  AMERICA. 


443 


schists,  whicli,  as  at  Cornwall,  include  the  cupriferous 
rjagaetites  of  tlie  region.  These  schists  include  hydrous 
mieacecus  minerals,  among  which  are  chlorite,  and  the 
greenish  foliated  silicate  of  copper,  magnesium,  and  alu- 
minium, to  which  I  have  given  the  name  of  venerite  (ante^ 
p.  357).  The  manner  in  which  lenticular  masses  of  pure 
serpentine,  sometimes  only  a  few  ounces  in  weight,  are 
found  imbedded  in  these  schists,  not  less  than  the  mode 
of  their  occurrence  in  the  limestones  at  this  horizon,  is 
such  as  to  suggest  very  forcibly  the  notion  that  they  have 
been  formed  under  conditions  not  unlike  those  which  have 
given  rise  to  chert  or  to  iron-stone  nodules.  No  large 
masses  of  serpentine  have,  so  far  as  known,  been  found 
at  this  horizon,  yet  they  may  be  expected. 

§  27.  We  have  next  to  notice  the  existence  of  a  bed  of 
serpentine  at  Syracuse,  New  York,  which  was,  in  1839, 
examined  and  described  by  Professor  Vanuxem,  then  en- 
gaged in  the  geological  survey  of  the  State.  The  locality, 
"on  the  Fort-Street  road,  to  tlie  east  of  Syracuse,"  or, 
according  to  Dr.  Lewis  Beck,  "on  the  hill,  a  short  distance 
east  of  the  mansion  of  Major  Burnet,  at  Syracuse,"  has 
long  since  been  concealed  by  the  growth  of  the  city,  and 
we  have,  so  far  as  I  am  aware,  no  other  description  than 
those  given  by  Vanuxem,  in  the  years  1839  and  1842,*  of 
which,  on  account  of  the  interest  and  significance  of  this 
curious  occurrence  of  serpentine,  I  make  the  following 
summary :  The  rocks  of  the  region,  as  is  well  known, 
belong  to  the  Onondaga  salt  group  of  the  New  York  series, 
and  occupy  a  position  near  the  summit  of  the  Silurian, 
being  overlaid  by  the  Lower  Helderberg,  and  resting 
upon  the  Niagara  division.  The  strata  are,  as  elsewhere 
throughout  this  region,  undisturbed  and  nearly  horizontal, 
the  inclination  at  Syracuse,  as  measured   by  Vanuxem, 

*  Vanuxem,  Third  Annual  Report  on  the  Geology  of  the  Thu-d  Dis- 
trict of  New  York,  pp.  260  and  283;  also  Final  Report  on  the  Geology  of 
the  Third  District,  pp.  108  and  110,  and  Beck's  Mineralogy  of  New  York, 
p.  275. 


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444      THE  GEOLOGICAL  HISTORY   OF   SEHrENTINES. 


[X. 


* 


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I  < 


being  less  than  thirty  feet  to  the  mile,  in  a  southwest 
direction.  The  thickness  of  the  Onondaga  salt  group  is 
subject  to  gi-eat  variations,  and  at  this  point,  not  far  from 
its  eastern  limit,  it  is  thinner  than  farther  west.  It  is 
described  by  our  author  as  here  cojisisting,  in  its  lower 
portion,  of  a  mass  of  red  shales,  "  .«rying  from  100  to  500 
feet  in  thickness,  passing  upward  into  a  body  of  greenish 
shales  including  more  or  less  gypsum,  and  followed  by  a 
third  division,  in  which  are  found  masses  of  gypsum  of 
economic  value. 

§  28.  These  occur  on  two  horizons,  one  at  the  base 
and  the  other  at  the  summit  of  the  division,  in  the  form 
of  lenticular  masses  included  in  soft  shales  or  marls, 
which  are  often  marked  by  hopper-shaped  cavities,  doubt- 
less formed  through  the  removal,  by  solution,  of  imbedded 
crystals  of  sea-salt.  Interposed  in  these  marls  is  found  a 
peculiar  porous  dolomite,  generally  drab  or  buff  in  color. 
The  cavities  in  this  are  very  irregular  in  form,  and  in 
most  cases  communicate  with  one  another.  They  are 
sometimes  spherical,  and  contain  crystalline  crusts,  besides 
some  pulverulent  carbonate  .of  lime.  They  also  vary 
greatly  in  size,  in  some  portions  attaining  a  diameter  of 
half  an  inch,  and  giving  the  rock  a  vesicular  aspect.  Our 
author  remarks,  "  The  cavities  of  these  porous  rocks  have 
no  analogy  whatever  with  those  derived  from  organic 
remains."  As  seen  in  one  locality,  "the  cells  show  that 
parts  of  the  rock  are  disposed  to  separate  into  very  thin 
layers  which  project  into  the  cells,  an  effect  wholly  at 
variance  with  aeriform  cavities,  but  evidently  the  result 
of  the  simultaneous  forming  of  the  rock  and  of  soluble 
minerals,  whose  removal  caused  the  cells  in  question " ; 
a  condition  of  things  which  Vanuxem  considers  analogous 
to  that  shown  by  the  hopper-shaped  cavities  in  the  asso- 
ciated marls. 

§  29.  The  distribution  of  this  porous  dolomite  in  the 
third  division  of  the  Onondaga  group  near  Syracuse  is 
somewhat  irregular.     Besides  a  well  defined  stratum  ex- 


l-im    •  -I 


X.] 


SERPENTINES  IN   NOIITII  AMERICA. 


445 


[X. 

iwest 

up  is 

from 

It  is 
lower 
to  500 
•eenisl^ 
d  by  a 
sum  of 

le  base 

he  form 

•  maris, 

5,  dovibt- 

nbedded 

,  found  a 

in  color. 

,  and  in 

fbey  are 

s,  besides 

ilso   vary 

uneter  of 

ect.     Our 

ocks  have 
n   organic 
show  that 
very  thin 
wholly  at 
the  result 
of  sohible 
[^l^uestion  " ; 
.  analogous 
II  the  asso- 

uite  in  the 
Syracuse  is 
stratum  ex- 


tending over  a  large  part  of  the  gypsum-bearing  region, 
and  from  three  to  four  feet  in  thickness,  Vanuxem  noticed 
other  "masses,  limited  in  extent,  without  fixed  positions, 
appearing  to  have  been  deposited  at  irregular  intervals  in 
the  marls " ;  while  in  some  places,  as  at  the  serpentine 
locality  about  to  be  described,  there  is  a  lower  mass,  with 
smaller  pores  than  that  above,  sometimes  attaining  a  thick- 
•^-^s  of  twenty  feet.  The  interval  between  the  upper  and 
jiuwer  gypsum-horizons,  from  various  sections  noticed  by 
Vanuxem,  would  appear  to  be  from  forty  to  fifty  feet. 
The  marls  found  in  this  interval  contain  more  or  less  dis- 
seminated gypsum,  and  in  some  cases  small  grains  or  crys- 
talline masses  of  sulphur,  and  more  rarely  crystalline 
plates  of  specular  iron  in  druses  in  the  dolomite,  as  ob- 
served and  shown  me  by  Dr.  Goessmann.  The  marls  are 
described  as  yellowish  or  brownish  in  color,  and  generally 
soft  and  shaly,  with  harder  masses  included.  Above  this 
gypsiferous  division,  is  a  fourth,  consisting  of  a  compact 
magnesian  limestone,  marked  by  the  presence  of  numer- 
ous small  needle-shaped  cavities,  which  forms  the  summit 
of  the  Onondaga  group. 

§  30.  It  is,  as  already  stated,  between  the  two  masses 
of  porous  dolomite  near  Syracuse  that  the  bed  of  the  ser- 
pentine was  observed.  Its  thickness  is  not  stated,  but  it 
was  said  to  extend  northward  "  for  many  rods."  Accord- 
ing to  the  original  notes  of  Vanuxem,  there  was  seen,  in 
ascending  the  hill,  after  passing  twenty  feet  of  the  lower 
porous  dolomite,  and  an  interval  concealed  by  soil,  "  first, 
a  marly  shale,  then  mixtures  with  more  carbonate  of  lime, 
some  compact,  some  crystalline,  some  confusedly  aggre- 
gated, presenting  cavities  lined  with  crystals  of  that  min- 
eral, and  containing  also  sulphate  of  strontian  in  the  mass 
and  in  the  cavities.  With  these,  and  above  these,  are 
other  aggregates  like  serpentine,  marble,  etc.,  with  pur- 
plish shale  or  slate,  which  are  followed  by  a  green  and 
blackish  trap-like  rock,  as  to  appearance,  but  too  soft  for 
that  rock."    After  this, —  that  is,  above  it, — is  a  mass 


' .  »  a 


Wt'ia 


446      THE   GEOLOOICAL   HISTORY   OF   SERrENTI.NES.  [X. 


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which  resembles  the  material  overlying  the  lower  beds  of 
gypsum,  and  this  last  is  covered  b}'^  the  upper  porous 
dolomite. 

§  31.  In  a  supplement  to  the  report  of  1839,  above 
quoted,  it  is  added,  "The  green  and  trap-like  rocks  ob- 
served near  the  top  of  the  hill  to  the  east  of  Syracuse, 
have  been  examined  so  far  as  time  would  admit.  They 
are  all  8eri)entines,  more  or  less  impure,  and  of  various 
shades  of  bottle-green,  black,  gray,  etc.  They  all  pro- 
duce sulphate  of  magnesia  with  oil  of  vitriol.  .  .  .  Some 
have  a  peculiar  appearance,  like  bronze,  owing  to  small 
gold-like  particles,  with  a  lamellar  structure,  resembling 
bronzite  or  metalloidal  diallage ;  also  other  particles, 
highly  translucent,  like  precious  serpentine,  with  fre- 
quently small  nuclei,  resembling  devitrifications  or  porcel- 
lanites,  colored  white,  yellow,  blood-red,  variegated,  etc. 
The  grain  of  this  is  like  common  serpentine.  In  other 
kinds,  the  mass  seems  to  be  made  of  small  globuliform 
concretions,  varying  in  size,  being  centres  of  aggregation. 
Some  are  of  dark  vitreous  serpentine,  others  of  the  com- 
pact kind,  the  enveloping  part  of  a  light  color."  Van- 
uxem's  farther  notes,  in  his  final  report,  add  some  impor- 
tant details  to  the  above.  He  says:  "The  great  mass  of 
entirely  altered  rock  is  a  well  characterized  serpentine, 
especially  when  examined  by  the  microscope."  He  men- 
tions, moreover,  the  occurrence  of  mica,  both  white  or 
light-colored  and  black,  besides  accretions  which  he  com- 
pares to  granite,  and  others  in  which  a  hornblende  takes 
the  place  of  mica,  forming  aggregates  resembling  syenite. 
He  also  describes  granular  carbonate  of  lime,  like  marble 
in  texture,  which  "  existed  as  accretions  or  nodules  envel- 
oped in  the  serpentine." 

§  32.  I  endeavored  many  years  since  to  obtain  speci- 
mens of  these  rocks,  and,  through  the  kindness  of  Prof. 
James  Hall,  secured  a  single  mass  of  the  ser])entine,  which 
contained  small  plates  of  a  copper-colored  bastite  or  bron- 
zite.   Neither  mica,  hornblende,  nor  an}'  other  crystalline 


X] 


RKIIPENTINES   IN  NORTH   AMERICA. 


447 


silicate,  was,  however,  present  in  the  mass,  which  was  n 
well  defined  serpentine,  with  some  iidniixture  of  carhon- 
ates.  It  agrees  closely  with  the  description  given  by 
Vanuxem,  being  an  aggregate  of  grains  and  rounded 
niassr'  .f  serpentine,  with  others  of  a  fine-grained  carbon- 
ate of  lime,  imbedded  in  a  greenish-gray  calcareous  base. 
The  colors  of  tiio  serpentine  vary  froi  ,  blackish-green  to 
greenish-white;  it  is  often  translucent,  a ikI  takes  a  high 
polish.  An  average  portion  of  this  rock  gave  to  acetic 
acid,  34.4P)  parts  of  carbonate  of  lime,  and  2.73  of  carbon- 
ate of  magnesia,  with  0.34  of  iron-oxyd  and  alumina,  leav- 
ing a  residue  of  62.50  of  insoluble  silicate.  This  was  a 
nearly  pure  serpentine,  as  shown  by  its  analysis.  It  was 
completely  decomrosed  by  sulphuric  acid,  and  gave  silica, 
40.67;  magnesia,  32.61;  ferrous  oxyd,  8.12;  alumina, 
6.13;  water,  12.77=99.30.  No  traces  of  either  chrome  or 
nickel  could  be  detected.  One  of  the  small  imbedded 
calcareous  masses  or  concretions  found  in  this  serpentine 
was  finely  granular,  greenish  in  color,  and  was  nearly 
pure  carbonate  of  lime.* 

§  33.  The  associated  shales  and  limestones  of  this  gyp- 
sum division  are,  however,  generally,  if  not  always,  highly 
magnesian.  Beck  found  twenty  per  cent  of  magnesia  in 
the  limestone  overlying  the  lower  range  of  gypsum-beds, 
and  the  precisely  similar  rocks  associated  with  the  gypsum 
at  the  same  horizon  in  Ontario  are  dolomitic,  the  porous 
or  vesicular  beds  being  nearly  pure  dolomite,  and  other 
specimens  of  the  limestones  and  shales  consisting  of  dolo- 
mite with  an  argillaceous  mixture,  the  latter  sometimes 
predominating.f 

§  34.  From  a  study  of  the  facts  before  us,  it  is  apparent 
that  we  have  here  evidences  of  the  formation  by  aqueous 
deposition  of  a  bed  of  concretionary  silicate  of  magnesia, 
taking  the  form  of  serpentine,  with  a  little  associated  bas- 

*  For  details  of  this  serpentine  and  its  analysis,  see  Amer.  Jour.  Sci- 
ence (2),  xxvi.,  203,  and  Geology  of  Canada,  1S03,  p.  635. 
t  Geology  of  Canada,  1868,  pp.  347,  625. 


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448      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  PC. 

tite  or  bronzite,  and  probably  some  otlier  crystalline  sili- 
cates. The  intimate  association  of  silicate  of  magnesia 
with  carbonate  of  lime  is  significant  when  it  is  considered 
that  the  magnesia  which  abounds  in  the  accompanying 
strata  is  in  the  form  of  dolomite,  and  serves  to  illustrate  the 
views  set  forth  in  §  13,  as  to  the  relation  between  the  car- 
bonates and  silicates  of  these  two  bases.  It  seems  probable 
that  we  have  in  this  deposit  the  results  of  some  spring  bring- 
ing to  the  surface,  in  this  locality,  waters  holding  in  solu- 
tion calcareous  or  alkaline  silicates,  which  have  given  rise 
to  a  silicate  of  magnesia,  in  accordance  with  the  reactions 
already  explained.  It  is  to  be  hoped  that  farther  re- 
searches at  this  geological  horizon  may  disclose  other 
localities  of  magnesian  silicates  similar  to  that  of  Syracuse. 
§  35.  We  may  recall  in  this  connection  some  facts 
about  the  occurrence  of  magnesian  silicates  in  other  geo- 
logical periods  more  recent  than  that  of  Syracuse.  De- 
posits of  sepiolite,  a  hydrous  silicate  approaching  to 
steatite  in  composition,  are  well  known  in  the  tertiary 
strata  of  the  Paris  basin,  in  Spain,  and  elsewhere  along 
the  Mediterranean.  I  have  long  since  described  some  of 
these  deposits,  and  have  discussed  at  length  their  chemi- 
cal and  geological  relations.*  Mention  should  here  be 
made  of  the  talc  found  with  the  anhydrous  sulphate  of 
lime  (karstenite)  in  the  schists  at  the  Mont  Cenis  tunnel, 
to  be  mentioned  farther  on  (§  62),  and  also  of  the  associ- 
ation of  gypsum  and  serpentine  in  the  crystalline  schists 
of  Fahlun,  in  Sweden.f  Freiesleben,  and,  after  him,  Fra- 
polli,  has  described  the  occurrence  of  a  magnesian  silicate 
which  occurs  frequently  in  the  mesozoic  gypsums  of 
Thuringia,  in  nodular  imbedded  masses  resembling  flints 
in  their  aspect  and  mode  of  occurrence,  but  composed 
essentially  of  a  soft  magnesian  silicate,  near  to  talc  in 
composition,  and  colored  bcown  with  bituminous  matter.^ 

•  Amer.  Jour.  Science  [2],  xxix.,  284;  and  xxx.,  286. 
t  See  the  author's  Chem.  and  Geol.  Essays,  p.  336. 
'  t  Bull.  Soc.  Geol.  de  France,  1847  [2],  iv.,  837. 


»• 


X.] 


SERPENTINES  IN  EUROPE. 


449 


ni.  —  SERPENTINES  IN  EUROPE. 

§  36.  Having  thus  passed  in  review  some  of  the  princi- 
pal facts  Icnown  with  regard  to  the  occurrence  of  serpen- 
tines in  North  America,  we  proceed  to  the  consideration 
of  the  same  rocks  in  different  parts  of  Europe,  where,  as 
shown  in  the  opening  sections  of  this  essay,  thoy  have 
long  been  objects  of  study,  and  have  been  alternately 
regarded  as  indigenous  and  as  exotic  in  character. 

The  hypothesis  of  the  igneous  and  eruptive  origin  of 
serpentine  is  well  illustrated  in  the  paper  by  Professor 
Bonney  on  the  serpentines  of  Cornwall,  England,  in  the 
"Quarterly  treological  Journal,"  for  November,  1877, 
supplemented  by  his  later  observations  on  the  geology  of 
that  region,  communicated  to  the  Geological  Society  of 
London  in  November,  1882,  and  published  iu  abstract  in 
the  "Geological  Magazine,"  .for  December,  1882;  in 
which  connection  should  also  be  consulted  his  paper  on 
Ligurian  and  Tuscan  serpentines,  in  the  same  magazine, 
for  August,  1879. 

§  37.  Bonney  at  first  accepted  the  then  generally  re- 
ceived opinion  that  the  crystalline  schists  in  which  the 
serpentines  of  Cornwall  are  included,  are  altered  paleozoic 
strata,  but  in  his  latest  studies  of  the  region  he  announces 
the  conclusion  that  the}'  are  not  paleozoic,  but  eozoic 
(archaean),  and  consist  of  a  great  series,  divided  into  three 
groups.  The  lower  one,  of  greenish  micaceous  and  horn- 
blendic  schists,  he  compares  with  those  of  Holyhead,  An- 
glesey, and  the  adjacent  shores  of  the  Menai  Strait,  in 
Wales.  The  rocks  of  these  localities,  belonging  to  the 
Pebidian  series  of  Hicks,  have  been  examined  b}'^  the 
present  writer,  and  by  him  compared  with  the  Huronian 
of  North  America.* 

§  38.  Above  these  greenish  schists  in  Cornwall,  accord- 
ing to  Bonney,  is  a  black  hornblendic  ^roup,  and  a  still 
higher  gvanulitic  group  with  granitic  bands ;  the  charac- 

*  Amer.  Joui.  Science,  1880,  vol.  xix.,  pp.  276, 281 ;  and  ante,  pp.  416-419. 


450      THE  GEOLOGICAL  HISTOKY  OF   SERPENTINES.  [X. 


!i     il 


ters  of  tliese  two  recalling  portions  of  the  Montalban  or 
upper  gneissic  series  of  North  America  and  of  the  Alps. 
It  is  in  the  lowest  of  these  three  divisions,  consisting 
chiefly  of  micaceous  and  hornblendic  schists,  that  the 
Cornish  serpentines  appear,  accompanied  by  so-called  gab- 
bros  or  greenstones.  Bonney  finds,  with  Boase  and  with 
De  la  Beche,  examples  of  apparent  interstratification  and 
passage  between  these  rocks  and  the  schists,  but  con- 
cludes, nevertheless,  that  there  is  evidence  that  the  ser- 
pentine was  introduced  after  the  crystallization  of  these, 
and  that  its  eruption  was  followed  by  that  of  gabbros  of 
two  dates,  aiid  subsequently  by  that  of  granitic  and  dark- 
colored  trappean  rocks.  He  throws  doubt  upon  the  an- 
cient hj'-pothesis  of  the  conversion  of  hornblendic  and 
pyroxenic  rocks  into  serpentine,  and  supposes  this  mineral 
species  to  have  resulted  from  the  hydration  of  an  olivine- 
rock,  such  as  Iherzolite,  which  consiiits  essentially  of  oli- 
vine with  enstatite ;  grains  of  both  of  which  species  may 
be  detected  by  the  microscope  in  thin  sections  of  some  of 
the  Cornish  serpentines.  According  to  John  Arthur 
Phillips,  some  of  the  so-called  greenstones  of  Cornwall 
are  eruptive,  while  others  are  undoubtedly  indigenous, 
and  graduate  into  the  crystalline  schists  of  the  region. 
Respecting  these,  the  writer  said,  in  1878,  "  These  bedded 
greenstones,  with  their  associated  crystalline  schists,  ap- 
pear to  have  strong  resemblances  to  the  rocks  of  the 
Huronian  series,  to  which  farther  study  will  probably 
show  them  to  belong."  * 

§  39.  Bonney  has  also  extended  his  observations  to 
the  serpentines  and  associated  rocks  in  Italy,  which  we 
have  included  uader  the  general  title  of  ophiolites.  This 
name,  and  the  kindred  one  of  ophites  (Greek,  dcpirr/g')^ 
alluding  to  their  greenish  color,  resembling  that  of  the 
skins  of  some  serpents,  has  been  extended  so  as  to  include 
both  true  serpentine  and  the  frequently  associated  rocks 
which  present  some  analogies  with  it  in  color.     In  fact,  we 

*  Harpers' Annual  Record  for  1878,  p.  308.  ..^ 


,0E» 


X.] 


SERPENTINES   IN  EUROPE. 


461 


3an  or 

Alps, 
sisting 
at  the 
;d  gab- 
id  witli 
on  and 
at  con- 
:he  ser- 
f  these, 
)bros  of 
id  dark- 

the  an- 
idic  and 
i  mineral 
1  olivine- 
ly  of  oli- 
icies  may 
I  some  of 
Arthur 

Cornwall 
digenous, 

,e  region. 

ie  bedded 

ihists,  ap- 

tcs   of  the 
probably 

rations  to 
[which  we 
Ites.    This 

lat  of  the 
[to  include 

ited  rocks 
lln  fact,  we 


pass  from  pure  serpentine,  and  admixtures  of  this  with  car- 
bonates, to  serpentinic  rocks  including  more  or  less  of  dial- 
lage,  bronzite,  or  bastite,  and  thence  to  aggregates  in 
which  an  admixture  of  these  with  a  feldspathic  element 
marks  a  transition  to  the  great  group  of  rocks  essentially 
made  up  of  an  anorthic  feldspar  with  a  pyroxenic  element 
(hornblende,  pyroxene,  enstatite,  etc.),  including  the  so- 
called  "greenstones," — diorites,  diabases,  and  eupho tides, 
— which  are  the  frequent  associates  of  serpentines.  All 
of  these  rocks  were  embraced  by  Savi  under  the  conve- 
nient name  of  the  ophiolitic  group. 

§  40.  The  name  of  gabbro  (from  an  Italian  locality  of 
these  rocks,  near  Leghorn)  was  adopted  and  extended  by 
Tozzetti,  in  the  last  century,  in  a  similar  sense.  His 
numerous  species  of  gabbro  embraced  alike  serpentine  and 
the  various  diallagic,  hornblendic,  and  feldspathic  rocks 
already  noticed,  of  which  the  red  gabbro,  or  gabbro  rosso, 
seems  but  a  locally  discolored  and  partially  decayed  form. 
The  name  of  gabbro  has  come,  with  many  lithologists,  to 
mean  a  diabase  ;  but  it  is  employed  in  such  a  very  indefi- 
nite manner  that  it  would  be  well  if  it  were  dropped  alto- 
gether from  use.*  It  is  often  made  to  include  the  granitone 
of  the  Tuscan  stone-workers,  the  so-called  euphotide,  in 
which,  as  we  are  told,  the  feldspathic  element  is  replaced 
by  saussurite.  Although  this  latter  term  is  often  given  to 
a  compact  variety  of  triclinic  feldspar,  the  true  saussurite 
is,  as  I  have  elsewhere  shown,  a  compact  zoisite,  distin- 
guished from  feldspar  by  its  much  greater  density  and 
hardness.  '  The  two  minerals  are,  however,  intimately 
associated  in  the  euphotides  alike  of  the  Alps  and  the 
Apennines,  as  seen  in  specimens  which  I  have  examined 
both  from  Monte  Rosa  f  and  from  Monteferrato,  where  I 
found  saussurite  in  1881.  . 

*  See,  in  this  connection,  Cocchi,  Bull.  Soc.  G^ol.  de  France  (1856), 
xiil.,  261;  also  his  valuable  memoir  on  the  Igneous  and  Sedimentary 
Rocks  of  Tuscany,  ihid.,  1861,  pp.  227-300.    Cocchi  was  a  pupil  of  Savi. 

t  Contributions  to  the  History  of  Euphotide  and  Saussurite,  Amer. 
Jour.  Science,  1858,  xxv.,  437.  " 


' 


452      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X. 


§  41.  The  results  of  Bonney's  studies  are  given  in  a 
paper  on  Ligurian  and  Tuscan  serpentines  in  the  "  Geo- 
logical Magazine,"  for  August,  1879.  He  therein  records 
his  observations  in  different  localities  in  these  regions, 
which,  for  reasons  to  be  made  apparent  farther  on,  we 
arrange  in  three  geographical  groups.  First,  ophiolites 
on  the  sea-coast  west  of  Genoa,  where  Bonney  describes 
the  serpentines  as  occurring  with  dark-colored  schists  and 
gabbros,  instancing  among  the  mineral  species  found  with 
them  pyroxene,  amphibole,  glaucophane,  chlorite,  and 
saussurite.  He  states  that  the  serpentines  of  this  region 
are  so  like  those  of  Cornwall  that  he  feels  justified  in 
claiming  for  them  a  similar  origin.  In  a  second  group,  he 
notices  the  serpentines  of  a  region  immediately  eastward 
of  the  first,  between  Genoa  and  Spezzia,  which  he  de- 
scribes as  very  similar  to  these.  Bonney  rejects  for  all  of 
these  serpentines,  as  for  those  of  Cornwall,  the  notion 
that  they  have  been  formed  by  metasomatosis  from  diorite, 
diabase,  or  hornblendic  rocks,  a  hypothesis  which  he  con- 
ceives to  have  been  founded  on  hasty  and  imperfect 
generalizations,  and  regards  them  as  generated  by  the 
hydration  of  intruded  olivine  rocks.  In  the  third  geo- 
graphical group  of  the  ophiolites  described  by  Bonney,  he 
places  those  of  Monteferrato  in  Prato,  near  Florence.  In 
each  of  these  districts  he  notices  the  close  resemblances 
between  the  ophiolitic  rocks  and  those  met  with  in  the 
similar  areas  in  Great  Britain,  and  supposes  an  intrusion 
of  serpentine,  or  rather  of  olivine  rock,  among  crystalline 
schists,  followed  by  a  later  intrusion  of  gabbro.  He  has 
no  hesitation  in  assigning  to  the  serpentines  of  these  three 
districts  similar  conditions  and  origin  to  those  in  Corn- 
wall, North  Wales,  and  Scotland,  remarking  that,  notwith- 
standing the  fact  that  the  Italian  serpentines  are,  in  part, 
at  least,  assigned  to  the  cenozoic  period,  "  they  are  practi- 
cally identical "  with  the  serpentines  and  gabbros  of  more 
ancient  times. 

§  42.  Bonney  further  calls  attention  to  the  breccias  of 


X.] 


SERPENTINES  IN  EUROPE. 


453 


serpentine  with  a  calcite  cement,  found  at  various  points 
with  these  Italian  serpentines,  and  concludes  that  the  ser- 
pentines have  been  brecciated  in  situ,  so  that  it  is 
possible  to  trace,  in  a  short  distance,  the  passage  from 
unbroken  or  slightly  fissured  blocks  to  completely  crushed 
and  recemented  fragments,  and  even  to  mixtures  of  finely 
broken  serpentine  cemented  by  carbonate  of  lime,  in  which 
he  notes,  here  and  there,  filmy  patches  of  a  serpentinous 
material,  as  if  it  had  been  redissolved  and  again  deposited. 
He  believes  that  the  crushing  took  place  after  the  rock 
became  a  serpentine.  The  correctness  of  these  views  of 
Bonney,  as  to  the  breccias,  I  can  confirm  from  my  own 
observations  in  the  same  regions,  and  also  from  my  studies 
of  similar  breccias,  accompanying  the  ophiolites  of  eastern 
Canada.  Gastaldi,  in  this  connection,  has  made  an  impor- 
tant observation  of  a  breccia  in  the  valley  of  Trebbia, 
resting  upon  a  diallagic  serpentine,  and  consisting  of 
cemented  fragments  of  silicious  and  argillaceous  slate  with 
limestone  (alberese),  the  paste  being  traversed  in  various 
directions  by  veins  of  chrysotile.* 

§  43.  Bonney 's  observations  thus  bring  us  face  to  face 
with  the  views  of  those  Italian  geologists  who  regard 
certain  of  these  serpentines  as  of  tertiary  age,  and  speak 
of  them  as  having  had  an  eruptive  origin,  although,  as  we 
shall  see,  their  views  of  the  genesis  of  these  rocks  differ  as 
widely  as  possible  from  those  of  Professor  Bonney.  In 
anticipation  of  the  International  Geological  Congress  at 
Bologna,  in  Se])tember,  1881,  the  Italian  geologists  had, 
under  the  direction  of  the  Royal  Geological  Commission 
(R.  Comitato  Geologico),  made  extraordinary  preparations 
for  the  study  and  the  full  discussion  of  the  problems  offered 
by  the  serpentines  of  Italy.  A  map,  prepared  for  the 
occasion,  was  published,  showing  the  localities  of  the 
ophiolitic  masses  for  the  whole  kingdom  on  a  scale  of 
l-l,lll,lllth  ;  besides  separate  maps  of  particular  regions 
on  a  scale  of  l-10,000th,  as  that  of  Mazzuoli  and  Issel  for 
*  Studll  geologic!  sulle  Alpi  occideutali,  parte  II.,  p.  61. 


I 


II 


i   II 


.I'?!! 


ilpll 


454      THE  GEOLOGICAL  HISTORY  OP  SERPENTIITES.  PC 

the  Riviera  di  Levants  in  Liguria,  and  that  of  Capaoci  for 
Moiiteferrato  in  Prato,  in  Tuscany ;  with  especial  memoirs 
on  these  districts,  also  published  by  the  R.  Comitato  Geo- 
logico,  in  1881.  Ophiolitic  rocks  are  met  with  in  greater 
or  smaller  outcrops  in  many  localities  from  the  Alps, 
throughout  the  Apennines,  and  as  far  as  Calabria.  To 
these,  the  studies  of  Taramelli,  Lovisato,  De  Giorgi,  and 
De  Stefani,  among  others,  in  addition  to  those  previously 
named,  have  contributed  a  great  body  of  information.  A 
collection  of  ophiolitic  rocks  from  various  localities  was 
also  made,  and  submitted  to  chemical  and  microscopical 
study  by  Cossa  of  Turin,  aided  by  Mattirolo,  the  results 
of  which  occui^y  about  200  pages,  illustrated  with  many 
plates,  in  the  fine  quarto  volume  recently  published  on 
Italian  lithology.* 

§  44.  During  the  International  Geological  Congress,  a 
special  meeting  was  held  for  the  discussion  of  the  question 
of  serpentines,  on  Sept.  30, 1881,  in  which  took  part  Tara- 
melli, Capacci,  Zacagna,  Sella,  Szabo,  Daubrde,  De  Chan- 
courtois,  and  the  writer,  who  presided  on  that  occasion. 
A  detailed  report  of  the  proceedings  at  this  meeting  is 
published  in  the  first  fasciculus  of  the  Bulletin  of  the  new 
Geological  Society  of  Italy,  pages  14-31,  followed  by  an 
address  on  the  general  subject  of  serpentines  by  the  pres- 
ent writer,  pages  32-38,  by  notes  on  the  same  subject  by 
De  Chancourtois,  pages  39-44,  and  finally  by  the  extended 
studies  of  Taramelli  on  the  Italian  serpentines,  pages  80- 
128.  It  is  impossible  to  speak  too  highly  of  the  zeal, 
the  industry,  and  the  scientific  spirit  exhibited  by  the 
Italian  geologists  in  these  researches  undertaken  for  the 
solution  of  the  question  of  the  ophiolites,  which  may  well 
be  held  up  as  an  example  to  be  followed  by  other  nations 
in  similar  circumstances. 

§  45.  Mention  should  also  be  made  of  the  brief  memoir, 
of  thirteen  pages,  in   the   French  language,  by  Pellati, 

*  Eicerche  Chimiche  e  Microscopiche  sui  Roccie  e  Mineral!  d'ltalia, 
Torino,  1881. 


9 


SERPENTINES  IN  EUROPE. 


455 


prepared  for  the  Geological  Congress,  entitled  "  fitudes 
8ur  les  Formations  Ophiolitiques  de  I'ltalio,"  in  which  are 
set  forth,  with  great  conciseness,  the  principal  facts  with 
regard  to  the  geography  and  the  geo  ogy  of  these  ophiolitic 
masses,  and  the  theoretical  views  entertained  with  regard 
to  them  by  various  Italian  geologists.  According  to  De 
Stefani,  whose  discussion  is  confined  to  the  ophiolites  of 
the  Apennines,  these  rocks  belong  to  three  distinct  hori- 
zons:—  1.  upper  eocene;  2.  upper  trias;  3.  paleozoic; 
none  of  them  pertaining  to  a  more  ancient  period.  These 
ophiolitic  rocks  form  zones  and  regular  beds  in  the  midst 
of  the  sedimentary  rocks,  and  in  no  case  plutonic  dikes. 
The  different  varieties  of  serpentine,  and  of  the  non-sedi- 
mentary rocivs  which  accompany  it,  are  themselves  found 
in  regular  alternating  bands.*  The  conception  of  this 
observer  as  to  the  mode  of  eruption  of  these  rocks  appears 
to  be  essentially  the  same  as  that  of  Issel,  Mattirolo,  and 
Capacci,  to  t  splained  farther  on  (§§  91-93  and  100).  . 
§  46.  The  more  recent  studies  of  the  R.  Comitato  Geo- 
logico,  as  announced  in  1881,  lead  them  to  reject  the 
views  of  De  Stefani  as  to  the  age  of  the  ophiolites,  and  to 
refer  the  whole  of  these  rocks  in  Italy  to  two  geological 
periods.  They  distinguish  ancient  serpentines,  probably 
pre-paleozoic,  and  younger  serpentines,  referred  to  the  ter- 
tiary. The  older  serpentines  appear  in  large  masses  to 
the  west  of  Genoa,  between  the  valleys  of  the  Polcevera 
and  the  Teiro,  and  from  thence  are  traced  to  Monviso, 
from  which  point  the  ophiolitic  group  passes  north-north- 
east to  Monte  Rosa,  and  thence,  by  the  canton  of  Ticino, 
to  the  Vjiltelline.  To  the  same  ancient  series  are  also 
referred  the  serpentines  of  the  north  of  Corsica,  those  of 
Elba  in  part,  and  those  of  northern  Calabria.  These 
ancient  serpentines,  according  to  Pellati,  follow  the  con- 
tour of  the  great  zone  of  old  gneissic  and  grnnitic  rocks, 
which  passes  along  the  Alps,  through  Corsica  and  the 
Tuscan  archipelago,  and  "re-appears  in  Calabria.  The 
*  Boll.  Soc.  Geologica  Italiana,  i.,  pp.  20-33. 


!  I 


45G      THE   GEOLOGICAL   HISTORY   OP   SEUPENTINES.  [X. 


older  geologists,  Collcgno,  Parcto,  and  Sisniondi,  regarded 
the  serpentines  of  the  areas  thus  defined  (in  common  with 
the  others  yet  to  be  mentioned),  as  having  been  erui)ted, 
like  granites,  jjorphyries,  and  basalts,  at  various  geological 
ages.  Gastaldi,  however,  as  early  as  1871,  assigned  the 
Alpine  serpentines  to  a  distinct  pro-paleozoic  horizon, 
which,  from  the  association  of  the  serpentines  with  vari- 
ous rocks  known  as  greenstones,  or  pictre  venli,  he  desig- 
nated as  the  pietre-verdi  zone,  and  compared  with  the 
Iluronian  of  North  America,  of  which  he  supposed  it  to 
occupy  the  horizon. 

§  47.  The  conclusions  of  Gastaldi  as  to  the  Ali)ine  ser- 
pentines have,  according  to  Pellati,  been  confirmed  by 
Baretti,  and  by  Taramelli,  the  latter  of  whom  clearly 
shows  that  the  view  held  by  many,  that  the  rocks  of  the 
pietre  verdi  are  carboniferous  or  triassic,  is  inadmissible, 
and  that  they  belong,  as  maintained  by  Gastaldi,  to  pre- 
paleozoic  or  eozoic  time.  All  of  the  ophiolitic  maswes 
west  of  the  meridian  of  Genoa,  as  well  as  those  of  north- 
ern Calabria,  are  by  Pellati  included  in  this  class. 

To  the  east  of  this  meridian,  according  to  Pellati,  we 
find  the  newer  or  tertiary  serpentines,  including,  first, 
those  of  eastern  Liguria,  which  have  their  greatest  devel- 
opment along  a  line  ruiniing  north-northwest  from  Spezzia, 
and  second,  those  of  the  Bolognese  Apennines,  consisting 
of  a  great  number  of  small  masses  scattered  between 
Florence  and  Reggio,  in  Emilia.  A  third  group  includes 
the  masses  of  serpentine  found  between  Grosseto  and 
San  Miniato,  in  addition  to  which  tertiary  serpentines  are 
indicated  in  Elba  and  in  the  upper  part  of  the  valley  of 
the  Tiber.  Fai  fher  south,  others  are  met  with  at  Lago- 
negro  in  the  Basilicate,  from  which  point  to  Neopoli  a 
remarkable  development  of  serpentines  is  found  along  the 
upper  part  of  the  valley  of  the  Sinni.  The  areas  of  ser- 
pentines thus  indicated  by  Pellati  are,  according  to  him, 
generally  found  in  the  midst  of  the  limestones,  argillites, 
and  sandstones  of  tjie  eocene,  except  in  the  case  of  those 


X.] 


ROCKS  OP  THE  ALPS. 


457 


b'^tween  Grosseto  and  San  Miniato,  tho  oiitorops  of  which 
are  often  Been  rising  out  of  pliocene  chiyu  and  sands. 

IV.  —  GEOLOGY  OF  THE  ALPS  AND  THE  APENNINES. 

§  48.  Before  proceeding  farther  in  tlie  discussion  of 
tlie  Italian  serpentines,  it  will  be  well  to  get  a  view  of  the 
present  state  of  our  knowledge  of  Alpine  geology,  and 
especially  of  the  conclusions  and  generalizations  of  Gas- 
taldi.  These,  so  far  as  the  Alpine  serpentines  are  con- 
cerned, are,  as  we  have  seen,  accepted  by  the  Comitato 
Geologico,  and,  this  conceded,  it  is  diflicult  to  escape  his 
wider  generalization  which  brings  the  whole  of  the  so- 
called  tertiary  serpentines  of  Italy  into  tlie  same  eozoic 
horizon  with  those  of  the  Alps. 

If  we  go  backward  to  the  early  history  of  Alpine  geol- 
ogy we  shall  therein  find  the  origin  of  the  well  known 
hypothesis  that  the  crystalline  stratified  rocks  are  but 
portions  of  paleozoic. or  more  recent  sediments  which,  in 
certain  parts  of  their  distribution,  have  undergone  a  pro- 
cess of  alteration  or  so-called  metamorphism.  The  iufn  - 
position  of  the  uncrystalline  to  the  crystalline  rocks  in 
Mont  Blanc,  first  noticed  by  De  Saussure,  was  thus  ex- 
plained by  Bertrand,  who  suggested  that  these  crystalline 
schists  were  altered  rocks  of  a  more  recent  date  than  the 
uncrystalline  mesozoic  strata  of  Chamonix.  This  notion 
was  adopted  without  critical  study  by  Keferstein,  INIurchi- 
son,  Lyell,  Studer,  Sismondi,  and  Elie  de  Beaumont, 
among  others,  till  it  was  generally  believed  that  the  crys- 
talline rocks  of  the  Alps  are  wholly  or  in  great  part  of 
mesozoic  and  cenozoic  age.  It  is  hardly  necessary  to  say 
that  this  hypothesis  in  the  Alps,  as  elsewhere,  was  based 
upon  false  stratigraphy.  I  have  elsewhere  discussed  it  in 
its  relations  to  Alpine  geology,  in  a  review  of  the  great 
work  of  Alphonse  Favre,*  whose  life-long  studies  in  the 
Alps  of  Savoy  have  shown  for  all  that  region  the  fallacy 

*  Araer.  Jour.  Science,  1872,  vol.  iii.,  pp.  0-10,  and  Chem.  and  Geol. 
Essays,  pp.  337-330.  . 


:i!l 

'  1  I 


In 


458     THE  GEOLOGICAL  IIISTOUY  OP   lEilPENTINES.  [X. 

of  the  nietaniovpliic  hypothesis.  The  fnrther  studies  of 
Gerlach,  of  Fr.  Von  Huuer,  of  Biirctti,  and  especially  of 
Gastaldi,  have  now  fully  established  the  great  anti(iuity 
of  the  crystalline  rocks  in  question,  and  have  enabled  us 
to  compare  them  with  the  pre-Cambrian  rocks  of  other 
regions.  It  is  not  here,  however,  the  time  nor  the  place 
to  discuss  this  (question,  except  so  far  as  is  necessary  to 
the  understanding  of  the  geological  relations  of  the  Italian 
serpentines. 

§  41).  The  work  of  Gastaldi,  interrupted  by  his  death 
in  1878,  was  unfortunately  left  incomplete.  We  have, 
however,  valuable  records  of  it  in  a  memoir  in  two  parts, 
published  in  1871  and  1874,  entitled,  "Studii  geologici 
sulle  Alpi  occidental! " ;  in  a  letter  to  De  Mortillet  in 
1872 ;  in  one  to  Zezi  in  1876,  ^nd  finally  in  one  to  Sella 
in  1877,  with  a  postscript  in  1878.*  These  various  papers 
are  illustrated  with  numerous  maps,  plans,  and  diagrams. 
In  attempting  to  gather  from  these  sources  a  brief  state- 
ment of  Gastaldi's  conclusions  as  to  the  geology  of  the 
Alps  and  the  Italian  peninsula,  I  feel  that  I  am  both  ren- 
dering a  veritable  service  to  science  and  paying  a  tribute 
to  the  memory  of  my  honored  friend  and  correspondent 
of  many  years. 

§  50.  The  "Studii,"  etc.,  contain,  besides  Gastaldi's 
own  descriptions  and  sections,  many  important  historical 
details  and  extracts  from  the  literature  of  the  subject.  In 
the  second  part  will  also  be  found  reproduced  two  en- 
graved sections,  the  one  by  Gerlach,  from  Monte  Rosa,  by 
Varallo  and  the  Lago  di  Orta  to  Arona  on  Lago  Maggiore, 

*  Studii  geologici  sulle  Alpl  occldentall ;  meraorle  del  Kegio  Comitato 
Geologico,  vols  I.  and  II.;  Deux  mots  sur  la  g^ologle  des  Alpes  cotti"  nes; 
lettre  i\  M.  de  Mortillet,  Comptes  Rendus  de  I'Acad.  des  Sciences  de 
Turin,  vol.  vll.,  28  avril,  1872;  Lettere  del  Prof.  B.  Gastaldi  all'  Ingeg- 
nere  P.  Zezl,  Boll,  del  R.  Com.  Geologico,  1876;  Sul  rllevaraente  geolo- 
gici fattl  nelle  Alpl  Plemontesl  durante  la  carapagna  del  1877,  lettere  del 
Prof.  Gastaldi  al  Presidente  Qulntlno  Sella;  Reale  Accademla  del  lilncel, 
memorle  della  classe  dl  sclenze  flslche,  ecc.  anno  CCLXXV.  (1877-78). 
See,  also,  the  writer,  in  Azoic  Rocks,  p.  245,  and  Cbem.  and  Geol.  Essays, 
pp.  336,347. 


.  jii  ..111  ■ 


X.] 


EOL'KS  OF  THE  ALl  S. 


459 


and  the  other  by  CaiU)  Neii,  from  the  same  point,  in  a 
course  more  to  the  soutlieiistwartl,  by  Valsesia,  to  Monte 
Fenera,  and  beyond.*  A  comparison  of  these  sectiona 
with  those  described  by  Gustaldi,  will  be  found  of  much 
value  for  the  elucidation  of  the  (luestiona  before  us. 
Starting  frcm  the  granitic  gneiss  of  Monte  Rosa  (the  cen- 
tral gneiss  of  Von  Iluuer,  and  the  ancient  gneiss  o(  Ger- 
lach  and  Gastaldi)  we  find  in  Neri's  section  a  breadth  of 
not  less  than  seven  kilometres  included  in  the  zone  of  the 
pietre  verdi,  and  described  as  a  stratilied  series  of  "ser- 
pentines, talc-schists,  etc.,"  followed  by  seven  kilometres 
additional,  designated  as  diorites ;  the  two  being  classed 
together  as  a  "protozoic  terrane."  To  this  succeeds  a 
breadth  of  not  less  than  fourteen  kilometres  occu^)ied  by 
what  is  described  as  a  more  recent  crystalline  terrane, 
conjecturally  referred  to  the  paleozoic  period,  and  consist- 
ing of  calcareous  schists  and  quartzites,  with  mica-schists, 
and  a  great  mass  of  intruded  granite.  Succeeding  this  is 
a  great  breadth  described  as  porphyry  or  porphyritic  con- 
glomerate, followed  by  limestones  and  dolomites,  all  of 
which  are  referred  to  the  trias,  and  appear  in  Monte 
Fenera,  succeeded  by  fossiliferous  liassic  and  tertiary 
strata. 

The  section  by  Gerlach,  from  Monte  Rosa  to  Arona, 
shows  above  the  ancient  central  gneiss  a  great  breadth 
described  simply  as  diorite,  having  at  its  base  a  thin  belt 
of  micaceous  schists,  and  above  it,  between  Varallo  and 
the  lake  of  Orta,  a  wide  extent  of  recent  gneiss  and 
granite,  followed,  to  the  east  of  the  lake,  by  gneissic 
mica-schists,  succeeded  by  porphyry,  until  we  reach  the 
dolomitic  limestone  at  Arona. 

§  51.  Coming  now  to  Gastaldi's  own  sections,  we  have 
one  from  Turin  passing  westward  to  the  Fre:ich  frontier, 
and  crossing  a  broad  mass  of  the  ce.i.tri>l  gneiss;  co  the 

*  The  section  by  Gerlach  is  probably  from  his  Karte  der  Penninischen 
Alpen;  Nouv.  M^tn.  de  la  Soc.  Helvet.  do  Sci.  Nat.,  18G9.  That  by  Neri 
is  from  the  Boll,  del  Club  Alphio,  vol.  viil.,  No.  22,  Torhio,  1874. 


!] 


mm 


:i:'M 


460      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X. 

west  of  which,  in  a  distance  of  forty  kilometres,  we  have, 
first,  three  and  a  half  kilometres  of  euphotide  and  serpen- 
tine, followed  by  about  the  same  breadth  of  mica-schists, 
calcareous  schists,  and  diorites,  and  finally  by  a  great 
extent  of  calcareous  schists,  with  numerous  intercalations 
of  serpentine  and,  towards  the  summit,  gypsum  and  dolo- 
mite. The  less  complete  section,  to  the  eastward  of  the 
central  gneiss,  shows  also  the  serpentinic  and  dioritic 
rocks  overlaid  by  mica-schists,  and  the  same  story  is 
repeated  in  other  sections. 

Subsequently,  in  his  letter  to  Zezi,  Gastaldi  describes 
and  figures  a  section  from  Monte  Bracco  through  Monviso 
and  Monte  Pelvo,  along  the  upper  part  of  the  valley  of 
the  Po,  and  the  valley  of  Varaita,  to  the  frontier.  His 
conclusions  from  the  study  of  all  these  sections  may  be 
thus  summed  up :  The  crystalline  rocks  of  the  Western 
Alps  are  classed  in  two  great  groups,  the  lower  of  which 
(the  central  gneiss  of  Von  Hauer)  was  described  by  Gas- 
taldi as  the  ancient  gneiss,  and  by  him  compared  with  the 
Laurentian  of  North  America.  It  consists  chiefly  of  a 
highly  feldspathic  granitic  gneiss,  sometimes  porphyritic 
or  glandular,  and  includes  bands  and  lenticular  masses  of 
quartzite  and  crystalline  limestone,  with  white  steatite, 
and  graphite.  Reposing  upon  the  ancient  gneiss,  is  a 
great  and  complex  group,  designated  by  Gastaldi  as  the 
"newer  crystalline  series,"  wliich,  from  the  frequent  pres- 
ence therein  of  serpentines,  diorites,  diabases,  and  related 
rocks  of  a  greenish  color,  is  also  called  by  him  the  zone  of 
the  greenstones,  or  the  pietre  verdi. 

§  61.  In  a  generalized  diagrammatic  section  which 
accompanies  Gastaldi's  last  published  statement  (his 
letter  to  Sella,  in  1878),  the  first  division  of  the  newer 
crystalline  series  is  described  as  a  great  mass  of  serpen- 
tine, followed  by  a  second  division  consisting  of  eupho- 
tide, succeeded,  after  an  interval  of  crystalline  schists, 
limestones,  and  gneissic  rocks,  by  a  series  made  up  of 
many   alternations    of   epidotic,    dioritic,   and  variolitic 


\m 


X.] 


ROCKS  OF  THE  ALPS. 


461 


schists,  with  green  steatite.  In  some  localities  Jire  found 
great  beds  of  Iherzolite  and  of  amphibolite,  with  varieties 
of  diorite,  and  rocks  in  \*'hich  a  triclinic  feldspar  prevails, 
together  with  schists  more  or  less  calcareous,  and  crystal- 
line limestones.  The  serpentines  and  their  associated 
ophiolitic  rocks,  which  constitute  the  lower  members  of 
the  newer  crystalline  series,  are  described  by  Gastaldi  as 
resting  in  some  cases  in  nearly  horizon lal  stratification 
upon  the  ancient  gneisses,  and,  elsewhere,  ae  overlying  the 
limestones  of  this  older  series,  from  which  their  uncon- 
formable superposition  may  be  inferred. 

§  52.  The  group  of  newer  crystalline  rocks,  as  given 
in  Gastaldi's  section  of  1878,  includes  also  what  he  desig- 
nates as  recent  gneiss  and  granite,  besides  various  unde- 
scribod  schists,  with  crystalline  limestones,  followed  by  a 
second  horizon  of  serpentines,  to  which  succeed  gypsum 
and  dolomites.  All  of  these,  as  is  shown  in  the  section 
from  Turin  to  the  frontier,  are  intercalated  with  quai  tzite, 
in  a  vast  series  of  schists  which  a^e  placed  above  the 
recent  gneiss  and  graniie.  Finally,  the  whole  series  is 
overlaid  by  the  uncrystallino  sediments  cf  the  anthracitic 
group,  of  carboniferous  age. 

§  53.  The  lithological  characters  of  the  lower  part  of 
this  vast  series  of  newer  crystalline  schists  are  sufficiently 
well  defined  in  the  various  sections  already  noticed.  As 
regards  those  which  immediately  succeed  the  serpentinic, 
chloritic,  and  talc-schist  zone. — the  group  of  "mica-schists" 
of  Neri,  the  "recent  gneiss  and  granite"  of  Gerlach  and 
Gastaldi,  we  get  additional  light  from  various  passages  in 
the  writings  of  the  latter.  They  are  spoken  of  in  one 
place  as  gneissic  mica-schists,  more  or  less  rich  in  horn- 
blende, in  which,  at  Traversella,  are  also  included  serpen- 
tines. Elsewhere,  the  rocks  of  the  same  area  are  succes- 
sively called  mica-schist,  recent  gneiss  and  mica-schists, 
gneissic  mica-schists,  and  also,  a  very  micaceoas  gneiss, 
often  passing  into  mica-pchist  and  sometimes  hornblendic. 
With  these,  or  with  the  lower  portions  of  the  series,  are 


ti 


I 


1^^ 


I  i 


462     THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  l^- 

associated  granitic  and  syenitic  rocks  which,  in  the  opinion 
of  Gastaldi,  are  not  eiaptive,  but  the  result  of  local  modi- 
fications of  the  surrounding  gneiss..  From  my  own  obser- 
vations, I  conclude  that,  while  these  recent  gneisses  in  the 
Alps,  as  in  North  America,  assume  a  highly  granitic 
aspect  in  certain  beds,  they  are  not  to  be  confounded  with 
veritable  intrusive  rocks  which  penetrate  them.        ' 

§  54.  Gastaldi  has  described  in  detail  and  figured  a 
section  in  the  Biellese,  a  region  carefully  mapped  by 
Qiiintino  Sella  and  G.  Berutti,  and  studied  both  by  Ger- 
lach  and  Gastaldi.*  Here,  in  the  section  as  given  by  the 
latter,  the  granite  or  granitic  gneiss  is  bounded  to  the 
northwest  by  serpentine,  diallagic  rooks,  "and  ui/her 
greenstones,"  followed  by  a  band  of  diorite.  To  this  suc- 
ceeds a  great  breadth  of  the  n<  wer  gneisses,  in  which  is 
included  a  large  dike  of  melaphyre,  evidently  of  eruptive 
and  posterior  origin,  and,  farther  to  the  westward,  a  mass 
of  syenite,  which  is  extensively  quarried,  and  has  been 
studied  with  great  care  and  described  by  Cossa  in  his 
work  already  mentioned.  I  had  the  good  fortune  to  visit 
this  well  known  region  in  1881,  in  company  with  Signor 
Quintino  Sella.  The  granitic  rock  of  the  eastern  part  of 
the  section  appeared  to  be  a  part  of  the  ancient  gne  3sic 
series  so  largely  developed  elsewhere  near  Blella,  and  con- 
sisting of  reddish  granitoid  gneisses,  sometimes  horn- 
blendic,  but  scarcely  micaceous,  often  thinly  banded, 
highly  contorted,  and  indistinguishable  from  much  of  the 
gneiss  of  the  Laurentides,  or  of  the  South  Mountain  in 
Pennsylvania,  east  of  Schuylkill.  Interstratified  with  it, 
near  Bie'la,  are  beds  of  coarsely  crystalline  impure  lime- 
stone, holding  graphite,  mica,  and  hornblende,  and  resem- 
bling closely  some  Laurentian  limestones.  Elsewhere  in 
the  Alps,  it  may  be  noted,  similar  gneisses  include  serpen- 
tinic  limestoPujj,  as  for  example  the  pale  green  ophicalcite 
found  by  Favre  in  the  gneiss  of  Mattenbach,  near  Lauter- 
brunnen,  which  is  indistinguishable  from  that  of  the  Lau- 
*  Gastaldi,  Studii,  etc.,  part  I.,  pp.  3  and  26. 


X.] 


EOCKS   OF  THE  ALPS. 


463 


re'  tian  of  Canada,  and  like  it  contains  Eozoon  Canadense.* 
It  is  well  known  that  similar  sevpentinic  aggregates  are 
often  found  with  the  limestones  in  the  ancient  gneisses  of 
Scandinavia  and  Finland,  as  well  as  in  North  America. 

§  55.  This  ancient  gneissic  series  in  the  Biellese  is 
directly  overlaid  by  the  ophiolitic  and  dioriti:  belt  (pietre 
verdi),  and  this  is  followed  to  the  west  by  the  newer 
gneisses  and  mica-schists,  which  cannot  be  distinguished 
from  those  found  in  the  vicinity  ci  Philadelphia,  or  in  the 
White  Mountains  of  New  Hampshire,  which  I  have  called 
Montalba.i.  The  intruded  mass  of  syenite,  made  up  of 
reddish  orthoclase  with  some  albite,  hornblende,  and  a 
little  sphene,  presents,  in  the  extensive  quarries  which  I 
visited,  the  massive  character  and  the  comparative  homo- 
geneousness  which  belong  to  a  plutonic  rock.  The  usu- 
ally great  breadth  of  ophiolitic  rocks  met  with  in  this  part 
of  the  Alps  is  here,  as  pointed  out  to  me  by  Signor  Sella, 
rapidly  reduced,  to  the  southward,  by  the  encroachment 
of  the  newer  gn  isses  on  the  westward  side,  and,  where 
the  crysti'Uine  rocks  sink  beneath  the  alluvial  plain,  does 
not  exceed  a  kilometre.  These  relations  suggest  a  trans- 
verse superpop'tion  of  the  newer  gneiss  series  alike  upon 
the  ophiolitic  group  and  the  older  gneiss,  of  which  we 
shall  find  evidence  elsewhere. 

§  56.  It  has  been  seen  that  the  designation  oi  pietre 
verdi  was  by  Neri  restricted  to  the  ophiolitic  group 
beneath  the  newer  gneisses,  which  he  referred  to  a  later 
and  distinct  geological  period.  Gastaldi,  on  the  other 
hand,  extended  the  term  so  as  to  include  not  only  the 
newer  gneisses  and  mica-schists,  but  the  vast  mass  of  crys- 
talline strata  between  these  and  the  anthracitic  series, 
with  their  included  gypsums  and  dolomites.  The  grounds 
of  this  extension  are  these :  Serpentines  are  not  confined 
to  the  lower  ophiolitic  zone,  but  also  occur  alike  among 
the  newer  gneisses  and  the  succeeding  crystalline  schists. 

*  Favre,  Recherches  g^ologiques  dans  la  Savoie,  etc.,  iii.,  320,  and 
also  Chem.  and  Geol.  Essays,  p.  342. 


464      THE  GEOLOGICAL  HISTORY  OF   SERPENTINES.  [X. 


It  is,  says  Gastaldi,  "  in  contact  with  the  gypsums  and 
dolomites  that  we  find  the  last  limit  of  the  serpentinous 
rocks  which,  for  us,  characterize  the  zone  of  the  pietre 
verdi."  This  was  in  1872,  in  his  letter  to  De  Mortillet, 
at  which  time  Gastaldi  was  disposed  to  place  in  a  separate 
group  the  crystalline  schists  above  the  horizon  of  the 
upper  serpentines.  He,  however,  subsequently  included 
the  whole  of  these  schists  in  the  zone  of  the  pietre  verdi. 

§  57.  As  will  be  made  apparent,  the  schists  for  a  great 
distance  below  this  horizon  are  not  to  be  separated  from 
those  above.  We  have  in  them,  in  fact,  a  third  great  crys- 
talline group,  overlying  the  younger  gneisses,  but  by  Gas- 
taldi included  with  these  and  the  lower  ophiolitic  group 
under  the  common  name  of  the  pietre-verdi  zone.  At 
other  times  Gastaldi  used  the  term  of  pietre  verdi  in  the 
more  restricted  sense  in  which  it  was  employed  by  Neri. 
He  speaks,  in  1874,  of  "the  pietre  verdi  properly  so 
called,"  and  in  this  sense  he  declares  it  to  be  comprised 
between  "  the  ancient  porphyroid  and  fundamental  gneiss" 
and  "the  recent  gneiss,  which  latter  is  finer  grained  and 
more  quartzose  than  the  older."  He  says  farther,  "  I  will 
not  assert  that  when  specimens  of  this  newer  gneiss  are 
confusedly  mixed  with  those  of  the  more  ancient,  it  would 
always  be  practicable  to  distinguish  them  petrographi- 
cally ;  but  I  do  not  hesitate  to  affirm  that,  on  the  ground, 
the  distinction  is  not  difficult,  on  account  of  the  frequent 
alternation  of  the  younger  gneiss  with  the  other  charac- 
teristic rocks  of  the  upper  series ;  while  the  older  gneiss, 
however  wide  its  extent,  is  generally  unmixed  with  other 
rocks."  * 

§  58.  The  newest  crystalline  group,  mentioned  as  over- 
lying the  younger  gneiss  and  mica-schist  series,  is  that  of 
the  argillo-talcose  schists  of  Favre,  the  gray  lustrous 
schists  of  Lory  (jglamschiefer)^  with  their  included  serpen- 
tine, gypsum,  karstenite,  dolomite,  micaceous  limestone, 
banded  and  statuary  marbles,  and  quartzites ;  a  group  very 

*  Studii,  part  II.,  p.  31. 


[X. 

s  and 

tiuou3 

pietre 

rtillet, 

sparate 

of  tlie 

.eluded 

)  verdi. 

a  great 

3d  from 

at  erys- 

by  Gas- 

3  group 

ne.    At 

i  in  the 

by  Neri. 

)erly    so 

)mprised 

L  gneiss" 

ned  and 
"  I  will 

neiss  are 
would 

rographi- 
ground, 
requent 
charac- 
r  gneiss, 
th  other 

as  over- 
is  that  of 
lustrous 
id  serpeu- 
■imestone, 
roup  very 


X.] 


EOCKS  OF  THE  ALPS. 


465 


conspicuous  in  Alpine  geology.  These  rocks  are  well 
seen  in  the  section  from  Turin  to  the  French  frontier, 
and  are  traversed  in  the  Mont  Cenis  tunnel.  (See  also 
§§  62-66.) 

§  59.  The  vast  thickness  assigned  by  various  observers 
to  this  eutire  series  of  newer  crystalline  schists,  counting 
from  the  ancient  gneiss  below,  is  a  remarkable  fact  in 
their  history.  We  have  seen  the  great  breadth  ascribed 
to  the  successive  zones  or  groups  in  the  sections  already 
noticed.  Gastaldi,  in  1876,  estimated  the  real  thickness 
of  the  pietre-verdi  zone,  including  the  upper  lustrous 
schists,  at  24,000  metres,  of  which  8000  metres,  or  one- 
third,  was  assigned  to  the  lower  ophiolitic  group,  or 
proper  pietre  verdi,  apparently  without  including  the 
younger  gneisses  and  mica-schists,  which  make  up  the 
middle  group.  To  the  upper  group,  as  seen  in  the  Mont 
Cenis  tunnel,  Sismondi  and  filie  de  Beaumont  assigned  a 
vertical  thickness  of  not  less  than  7000  metres,  and  Rene- 
vier  finds  for  it  elsewhere  an  apparent  thickness  of  6000 
metres. 

§  60.  We  ha^'e  hitherto  spoken  of  the  Western  Alps, 
and  the  sections  as  yet  noticed  do  not  extend  to  the  east- 
ward of  Lago  Maggioic.  The  map  by  Von  Hauer,  of  the 
Lombard  and  Venetian  Alps,  published  in  1866-68,  em- 
braces the  region  from  this  meridian  eastward,  and  shows 
the  same  order  of  succession  as  that  laid  down  by  Gerlach 
in  the  west.*  The  various  groups,  as  indicated  by  Von 
Hauer,  are  as  follows :  1.  The  ancient  gneiss  and  granitic 
rocks,  designated  by  him  as  the  "  Central  gneiss " ;  2. 
Greenish  schistose  rocks,  described  as  hornblendic, 
dioritic,  and  euphotidic,  with  serpentines,  chloritic  and 
talc-schists  ;  3.  Saccharoidal  limestones,  more  or  less  mica- 
ceous, with  talc-schists ;  4.  Serpentines,  euphotide,  diorite, 
and  talcose  and  chloritic  schists,  as  before ;    5.    A  fine- 

*  Gastaldi,  Studii,  part  I.,  p.  18,  and  Fr.  Von  Hauer,  Geologische 
tJbersiclitskartfc  der  Osterreichlsch-Ungarischen  Monarchic,  fol.  v.,  West- 
Alpen,  u.  fol.  vi.,  Ost-Alpen;  Wien,  1866-68. 


1"  , 


46G      THE  GEOLOGICAL  HISTORY  OP  SERPENTINES.  [X. 

grained  gneiss,  designated  as  "  Recent  gneiss " ;  and  6. 
Mica-schist,  with  hornblendic  and  feldspathic  varieties. 
We  have  evidently  here  the  same  great  pietre-verdi  zone 
as  in  the  west,  comprised  between  the  older  gneiss  and 
the  younger  gneiss  with  its  attendant  mica-schists.  There 
appears,  however,  a  considerable  development  of  crystal- 
line limestones  in  the  midst  of  the  pietre  verdi. 

§  61.  Further  light  is  thrown  upon  the  question  of 
these  crystalline  rocks  of  the  Alps  by  the  observations  of 
Renevier,  Heim,  and  Lory,  especially  as  embodied  in  an 
essay  by  the  latter  on  tlie  Western  Alps,  published  in 
1878,  and  in  a  study  of  the  geology  of  the  Simplon,  by 
Renevier,  in  the  same  year.*  According  to  Lory,  the 
ancient  crystalline  rocks,  designated  by  him  as  the  "  Primi- 
tive schists,"  as  seen  in  the  Simplon,  and  elsewhere  in 
this  region,  include  three  groups,  in  ascending  order: 
1.  The  stage  of  the  Gneiss,  properly  so  called,  including 
varieties  from  the  highly  feldspathic  and  massive  grani- 
toid gneisses  to  others  less  feldspathic  and  more  distinctly 
laminated.  2.  The  stage  of  the  Mica-schists,  often  gar- 
netiferous,  which  embraces,  however,  alternating  beds  of 
gneiss,  the  two  rocks  passing  insensibly  the  one  into 
the  other.  These  mica-schists,  tender,  and  gray  in  color, 
are  often  more  or  less  impregnated  with  carbonate  of 
lime,  and  contain  bands  of  limestone  and  marble.  3.  The 
st?ge  of  the  Talc-schists,  a  term  which,  as  Lory  explains, 
he  uses  in  a  very  general  sense,  to  include  not  only  stea- 
tites, but  talcose,  chloritic,  and  hornblendic  schists,  the 
latter  sometimes  without  visible  feldspar,  but  often  more 
or  less  feldspathic,  and  thus  passing  into  varieties  desig- 
nated by  him  as  talcose,  chloritic,  or  hornblendic  gneiss. 
The  so-called  protogine  of  the  Alps,  according  to  Lory,  is 
but  a  granitoid  variety  of  talcose  or  chloritic  gneiss,  sub- 

*  Essai  sur  I'orographie  des  Alpes  occidentales,  par  Charles  Lory, 
p.  76  ;  Paris  and  Orenoble,  1878.  Also,  Structure  geologique  du  massif 
du  Simplon,  etc.,  par  E.  Renevier,  Bull,  de  la  see.  vaudoise  des  sciences 
naturelles,  vol.  xv.,  No.  79. 


p> 


X.] 


BOOKS  OP  THE  ALPS. 


407 


ind  6. 
•ieties. 
i  zone 
S8  and 
There 
jrystal- 

tion  of 

Aons  of 

1  in  an 

shed  in 

plon,  by 

ory,  the 
"  Primi- 

vhere  in 

g  order: 

including 

xe  grani- 

distinctly 

)ften  gar- 
beds  of 
one  into 
in  color, 

honate  of 
.     3.  The 
explains, 
only  stea- 
jhists,  the 
iften  more 
[ties  desig- 
lUc  gneiss. 
|to  Lory,  is 
;nei8S,  sub- 

bhavles  Lory, 
lue  du  massif 
des  sciences 


ordinate  to  the  talc-schist  stage,  and  passing  insensibly 
into  the  talcose  and  chloritic  schists,  with  which  it  alter- 
nates. It  is  not,  therefore,  as  some  have  supposed,  tlio 
fundamental  rock  of  the  Alps,  but  belongs  to  an  upper 
portion  of  the  Priznitive  schists.  The  lower  gneiss  of  the 
Simplon,  described  by  Gerlach  as  the  gneiss  of  Antigorio, 
to  which  this  distinction  apparently  belongs,  is  further 
noticed  b\  Kenevier,  who  assigns  to  it  a  great  thickness, 
and  regards  it  as  the  basal  rock  of  the  Alps,  corresponding 
to  the  ancient  gneiss  of  Gastaldi  and  the  central  gneiss  of 
Von  Hauer.  The  succeeding  mica-schists,  often  garneti- 
ferous  and  calcareous,  with  alternating  gneiss  and  lime- 
stone bands,  have  also  a  great  volume.  The  hornblendic 
schists  play  a  less  important  part  in  the  series.  Though 
these  sometimes  contain  a  little  mica,  or  a  little  chlorite, 
chloritic  schists  are  rare,  and  the  stage  of  the  talc-schists, 
indicated  by  Lory,  is  not  mentioned  by  Renevier  in  his 
description  of  the  Simplon. 

§  62.  The  term  of  Primitive  schists,  as  employed  by 
Lory  and  by  Renevier,  is  not  extended  to  the  gray  lus- 
trous schists,  already  noticed  as  forming  the  upper  part  of 
the  great  series  included  by  Gastaldi  in  the  pietre  verdi. 
These  upper  schists  are  by  Lory  regarded  as  altered  trias, 
a  view  in  which  Renevier  acquiesces.  They  are,  for  the 
most  part,  soft,  glistening,  and  talcose  in  aspect,  and  have 
been  variously  described  as  argillo-micaceous  and  argillo- 
talcose  schists,  being  sometimes,  according  to  Lory,  true 
sericite-schists.*  They  closely  resemble  the  crystalline 
schists  with  hydrous  micas  which  abound  in  the  Primal 
and  Auroral  divisions  of  Rogers  (Taconian),  as  seen  in 
eastern  Pennsylvania.  These  schists  in  the  Alps  are 
traversed  by  veins  of  calcite  and  of  quartz,  and  include, 
besides  great  beds  of  quartz-rock  (often  a  detrital  sand- 
stone), beds  of  limestone,  sometimes  micaceous,  of  bana  d 
and  of  white  granular  marbles,  of  dolomite  and  of  gyp- 
sum. This  latter,  in  the  subterranean  exposures  made  in 
*  Bull.  soc.  gdol.  de  France,  z.,  29. 


/ 


jjft; 


1. 


'.^if*K.. 


4J8       THE  GEOLOGICAL  HISTOUY  OF  SERPENTINES.  [X. 

the  Mont  Cenis  tunnel,  is  represented  by  anhydrous  sul- 
phate of  lime  (karstenite),  and  is  accompanied  by  rock- 
salt  and  sulphur.  Magnesian  silicates  are  also  found  in 
this  group ;  nodules  of  talc  are  imbedded  in  the  karsten- 
ite, chlorite  occurs  in  veins  and  layers,  and  beds  of  ser- 
pentine (and  of  euphotide,  according  to  Gastaldi)  are 
interstratified  with  these  shining  argillo-talcose  schists. 

§  63.  The  resemblances  in  mineral  character  between 
these  upper  argillo-talcose  schists  with  chlori*^<3  and  with 
interstratified  serpentines,  and  the  lower  or  true  pietre- 
verdi  zone,  are  obvious.  Lory  has  moreover  remarked  the 
likeness  between  these  upper  schists  with  limestones  and 
the  mica-schists  with  limestones  in  the  horizon  of  the 
newer  gneiss  series  (included  by  him  in  the  Primitive 
schists)  as  leading  to  the  confounding  of  the  two.  This 
resemblance,  he  suggests,  "may  have  thrown  some  ob- 
scurity "  upon  the  relations  of  these  various  rocks,  and 
the  structure  of  the  region.  It  will  not  have  escaped  the 
notice  of  our  readers  that  in  the  description  of  the  section 
of  the  Simplon  there  is  no  recognition  whatever  of  the 
great  mass  of  serpentines,  euphotides,  and  other  opliiolitic 
rocks  belonging  to  the  pietre  verdi,  which  elsewhere  are 
found  at  the  base  of  the  newer  crystalline  schists,  occupy- 
ing a  horizon  between  the  older  and  the  younger  gneisses. 

§  64.  It  will  also  be  noted  that  Lory  places  a  horizon 
of  talc-schists,  with  chloritic  rocks,  etc.,  at  the  summit  of 
the  newer  gneisses,  and  the  view  naturally  suggests  itself 
that  Lory  has  himself  confounded  the  lustrous  schists  of 
the  upper  series  and  their  magnesian  rocks,  with  the  great 
lower  ophiolitic  zone.  This  latter  would  appear  to  be 
wanting  in  the  section  of  the  Simplon,  where  it  is  not 
noticed  by  Renevier.  Lory  thus  places  above  the  younger 
gneisses  a  talc-schist  series  to  which  he  refers  many  of  the 
types  of  rocks  met  with  in  the  great  ophiolitic  and  talc- 
schist  zone,  which  elsewhere  underlies  these  younger 
gneisses,  and  in  which  the  protogines  are  probably  in- 
cluded.    In  this  way  the  apparent  discrepancy  between 


us  sul- 
y  rock- 
und  in 
:ai'sten- 
of  ser- 
di)  are 
lists, 
between 
nd  with 
3  pietre- 
rlced  the 
)nes  and 
1  of  the 
Primitive 
ro.    This 
some  ob- 
ocks,  and 
caped  the 
^le  section 
er  of  the 
oplnolitio 
where  are 
ts,  occupy- 
r  gneisses, 
a  horizon 
summit  of 
rests  itself 
schists  of 
the  great 
lear  to  be 
it  is  not 
le  younger 
lany  of  the 
and  talc- 
le    younger 
[robably  in- 
>y  between 


X.) 


EOCKS  OF  THE  ALPS, 


469 


Lory  and  all  the  observers  hitherto  mentioned  is  ex- 
plained, as  proposed  by  the  present  writer  in  1881.  The 
rehitions  observed  in  the  Biellese,  as  already  noticed,  sug- 
gest tliat  the  younger  gneisses  were  deposited  unconform- 
ably,  alike  upon  the  older  gneisses  and  the  great  ophiolitic 
group,  as  is  the  case  in  numy  otiier  regions. 

§  65.  In  like  manner,  according  to  Lory,  the  lustrous 
schisis  themselves,  with  included  serpentines  (which  he 
regards  as  contemporaneous  eruptions),  rest  directly  up- 
on the  ancient  gneisses  in  the  Levanna,  between  Susa  and 
Lanzo.  Other  evidences  of  a  want  of  conformity  between 
these  various  groups  of  ancient  schists  in  the  Alps  are 
not  wanting.  At  the  Col  de  Mont  Gendvre,  as  described 
by  Lory,  there  appears  through  the  lustrous  schists  a  great 
"mass  of  non-stratlHed  rocks,  comprising  euphotides,  ser- 
pentines, variolites,  and  various  rocks  of  passage  between 
these  types."  These  ophiolitic  rocks,  which  correspond 
to  the  lower  part  of  the  pietre-verdi  zone  of  Gastaldi,  are 
regarded  by  Lory  as  eruptive,  and  have  not  been  recog- 
nized in  his  scheme  of  the  divisions  of  the  primitive 
schists.  Their  appearance  among  the  lustrous  schists  is 
thus,  according  to  him,  an  irruption  in  the  midst  of  the 
trias,  instead  of  being,  as  we  should  rather  regard  it,  a 
protrusion  of  a  portion  of  the  pietre-verdi  zone  in  the 
midst  of  the  lustrous  schists,  which  are  here  unconform- 
ably  superimposed  upon  it,  as  elsewhere  upon  the  ancient 
gneisses. 

§  66.  The  history  of  the  upper  or  argillo-talcose  schists 
of  the  section  under  consideration  will  be  found  discussed 
at  some  length  by  the  present  writer  in  a  review  of  Favre 
on  the  geology  of  the  Alps  in  1872.  It  was  there  shown 
that  these,  though  very  distinct  from  and  unlike  the 
underlying  micaceous,  hornblendic  schists  and  gneiss,  are 
really  crystalline  schists,  and  very  unlike  the  normal  trias 
of  the  region,  to  the  horizon  of  which  they  had  been 
referred  by  most  geologists.  The  section  of  them  afforded 
by  the  Mont  Cenis  tunnel  was  then  and  there  discussed, 


MM 


',•,1^.(1     I  'I: 


'B 


tf  .r  ■■^-. 


i  .^    . ,  ■ 


m0 


U    I 


470     THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X. 

niid  many  reasons  were  given  for  rejecting  the  notion  of 
their  triassic  age,  and  for  assigning  them  to  the  eozoio 
period.  As  was  shown  in  u  subsequent  note  to  that  re- 
view, Favre,  after  publishing  his  book  in  1867,  was  led  to 
adopt  the  view  advanced  by  Gastaldi  in  1871,  that  these 
schists  were  pre-carboniferous,  though  probably  paleozoic, 
a  conclusion  which  the  latter  subsequently  exchanged  for 
that  of  their  eozoic  age,  as  maintained  by  the  present 
writer  since  1872.* 

§  67.  The  section  traversed  by  the  St.  Gothard  tunnel 
furnishes  important  details  for  Alpine  geology.  This 
work,  beginning  at  Goschenen,  on  the  north,  ends  at 
Airolo  on  the  south  side  of  the  mountain,  the  entire  dis- 
tance being  14,920  metres.  The  first  2000  metres  from 
the  northern  portal  are  in  the  massive  rock  of  the  Fin- 
steraarhorn,  called  by  various  observers  granite  or  granitic 
gneiss,  and  by  Stapff  regarded  as  an  older  gneiss  than 
that  of  the  remaining  part  of  the  section.  Between  this 
and  the  mountain  of  St.  Gothard  is  included  the  closely 
folded  synclinal  basin  of  Urseren,  while  the  southern 
jjortal,  at  Airolo,  is  on  the  northern  side  of  the  similar 
basin  of  Ticino;  the  great  intermediate  mountain-mass  of 
highly  inclined  and  faulted  strata,  presenting  a  fan-shaped 
arrangement.  The  basin  of  Urseren  holds,  folded  in 
gneiss  and  mica-schist,  a  group  of  strata  consisting  of  ar- 
gillites,  sometimes  calcareous  and  often  graphitic,  with 
gray  lustrous,  unctuous  sericite-schists,  together  with 
quartzose  layers,  and  others  which,  from  a  development 
of  feldspars,  pass  into  an  imperfect  gneiss.  With  these 
are  interstratified  granular  crystalline  limestones,  white 
or  banded  with  gray,  with  dolomite  and  karstenite.  Some 
of  the  limestones  included  in  this  synclinal  have  afforded 
indistinct  organic  forms,  and  the  series  has  been  referred, 
like  the  similar  rocks  noticed  in  previous  sections,  to  the 
mesozoic  period.     A  repetition  of  these  is  met  with  in  the 

*  Amer.  Jour.  Science  (3),  iii.,  pp.  1-15,  also  Chem.  and  Geol.  Essays, 
pp.  333,  336,  and  347. 


X.] 


ROCKS  OF  THE  ALPS. 


471 


Ticino  basin,  on  the  south  side  of  the  mountain.  Apart 
from  these,  the  great  mass  of  strata  along  the  line  of  tlie 
tunnel  consists  of  micaceous  gneisses  and  mica-schists 
with  hornblendic  bands,  the  whole  having  the  characters 
of  the  younger  gneissic  series,  and  very  distinct  from  the 
older  gneiss  of  the  northern  portion.*  If  this  latter  be 
the  central  gneiss,  the  pietre-verdi  zone  is  here  absent. 

I  have  not  seen  the  gneiss  of  the  Finsteraarhorn,  but, 
having  examined  the  gneisses  and  mica-schists  of  the  St. 
Gothard  and  the  Ticino,  can  affirm  that  they  have  the 
lithological  characters  of  the  Montalban  series  of  North 
America  and  of  the  younger  gneiss  and  mica-schists  of 
Gastaldi  and  Von  Hauer,  in  which  they  were  included  by 
the  Austro-Hungarian  geological  survey.  (§  60.)  The 
serpentines  of  the  younger  gneiss,  as  seen  in  the  St.  Goth- 
ard section,  will  be  described  in  part  vii. 

§  68.  With  regard  to  the  presence  of  granites  in  these 
regions,  Cordier,  as  cited  by  Lory,  long  ago  asserted  that 
true  granites,  occurring  in  veins  or  transversal  inclusions, 
arc  rare  in  the  Western  Alps.  He,  however,  excepted 
some  masses,  of  which  the  granites  of  Baveno  may  be 
taken  as  a  type,  and  others,  which  are  rather  veins  of 
segregation  (endogenous)  than  of  injection.f  For  the 
rest,  Cordier  regarded  the  granites  of  the  Alps  as  strati- 
fied rocks.  Gastaldi,  going  still  farther  in  his  protest 
against  plutonism,  admits,  in  the  regions  examined  by 
him,  none  but  stratified  rocks  of  aqueous  origin,  and  has 
included  in  his  sections  masses  that  I  regard  as  iffneous 
and  intrusive  rocks,  but  which  are  by  him  confounded 
with  true  indigenous  gneissic  rocks  under  the  title  of 
"  recent  gneiss  and  granite." 

As  regards  the  porphyry  mentioned  in  the  sections  of 
Neri  as  above  the  recent  gneisses,  and  that  placed  by 
Gastaldi  above  the  lustrous  schists,  it  would  appear  that 

*  For  full  details  of  this  section  see  Profll  g^ologique  du  St.  Gothard, 
etc.,  par  Dr.  F.  M.  Stapff;  Berne,  1881. 

t  See  the  author,  in  Chem.  and  Geol.  Essays,  p.  331. 


'1     i 

111    ! 


472      THE  GEOLOOICAL   HISTOUY  OF  SERPENTINES.  IX. 

the  latter  employed  this  term  in  a  very  vague  sense,  since 
he  speaks  of  the  foldspathic  and  quartziferous  porphyries 
of  this  region  as  presenting  great  varieties  in  structure 
and  in  composition,  and  as  passing  into  other  rocks, 
notably  into  granites,  from  which  it  is  often  dillicult  to 
separate  them.*  Ho  seems,  under  the  general  term 
of  i)orphyry,  to  have  included  both  stratified  rocks  at 
different  horizons,  and  intruded  masses  of  various 
kinds. 

§  G9.  From  the  various  descriptions  and  sections  of 
the  Alpine  rocks,  which  we  have  here  considered,  it  ajv 
pears  that  they  may  be  included  in  four  distinct  groups, 
which  are  as  follows  in  ascending  order:  — 

I.  The  central  or  ancient  granitoid  gneiss,  with  occa- 
sional quartzites  and  crystalline  limestones,  bearing  graph- 
ite and  many  crystalline  minerals.  This  group  we  refer, 
with  Gastaldi,  to  the  Laurentian. 

II.  The  great  group  of  the  pietre  verdi  proper,  in 
which,  besides  serpentines  and  ophiolitic  rocks,  are  in- 
cluded bands  of  limestone,  and  also  apparently  certain 
gneissoid  rocks,  the  protogine  or  the  talcose  gneiss  of 
Lory  and  Taramelli.  (§§  61,  78.)  It  is  worthy  of  remark 
that  although  Gastaldi,  like  Neri,  Gerlach,  and  Von  Hauer, 
placed  the  great  group  of  recent  gneiss  and  mica-schists 
above  the  true  pietre-verdi  zone,  Avhich  he  declared  to  be 
confined  between  the  older  and  the  newer  gneiss,  he,  in 
his  last  published  sketch,  indicated,  besides  this,  another 
horizon  of  "recent  gneiss  and  granite"  (not  elsewhere 
noticed  by  him)  intercalated  in  the  pietre-verdi  zone,  as 
thus  limited,  and  probably  corresponding  to  these  talcose 
gneisses.  This  second  or  pietre-verdi  group,  we  refer 
with  Gastaldi  to  the  Huronian. 

III.  The  younger  gneiss  and  mica-schist  series,"  with 
hornblendic  varieties  and  intercalated  crystalline  lime- 
stones, and  in  some  cases  with  serpentines  and  eupho- 
tides.     This  group,  upon  the  lithological  characters  of 

♦  Studii,  etc.,  part  H.,  p.  34.         ^ 


I  ' 


i 


x.i 


ROCKS   OF  THE   ALPS. 


478 


wliich  we  have  already  insisted  (§§  58,  55,  67),  wo  regard 
as  the  ie[)r('soiitutivo  of  the  Montalbaii. 

IV.  The  upper  lustrous  schists,  with  gypsums  and  kar- 
stcuite  and  tale,  with  interstratiliod  srvjeutines,  (^uartz- 
ites,  often  sandstones,  argillites,  dolomites,  micaceous 
limestones,  and  bandea  and  statuary  marbles.  This 
group,  as  wo  have  already  indicated,  presents  many  re- 
scmbhmces  with  the  great  Lower  Taconic  or  Taconian 
series  of  North  America.  In  it  are  included  by  Gastaldi, 
the  crystalline  limestones  of  the  Apuan  Alps,  which 
yield  the  statuary  marbles  of  Carrara  and  of  Massa. 

§  70.  In  the  Western  Alps  there  is,  so  far  as  is  known, 
no  evidence  of  the  lower  paleozoic  rocks,  —  the  sandstones 
with  anthracite,  which  succeed  the  crystalline  schists, 
containing  in  many  places  a  carboniferous  flora.  The 
,3ame,  according  to  Gastaldi,  is  true  in  the  Maritime  Alps 
and  the  Apennines,  where,  in  many  cases,  he  finds  the 
crystalline  schists  overlaid  by  the  anthracitic  series.  Thus, 
in  the  valley  of  Macra,  above  the  seipentines  are  found 
calcareous  schists  with  crystalline  limestones  and  quartz- 
ites,  which  are  successively  overlaid  by  the  carboniferous 
sandstones,  the  limestones  of  the  trias,  with  their  charac- 
teristic fauna,  the  lias,  the  cretaceous  and  the  nummulitic 
beds.  At  Torre  Mondovi,  the  serpentines  are  overlaid  by 
fossiliferous  triassic  limestones,  while  in  the  valley  of 
Bormida  they  are  directly  succeeded  by  the  marls,  sand- 
stones, and  conglomerates  of  the  lower  niiocene,  and  in 
the  valleys  of  Staffora  and  Polcevera  by  the  alberese  and 
the  macigno  of  the  eocene.  The  supposed  pre-curbonifer- 
ous  fauna  found  by  Michelotti  in  the  limestones  of 
Chaberton,  has,  on  farther  examination  by  Prof.  Mene- 
ghini,  been  shown  to  be  of  triassic  age.* 

§  7L  Passing  now  from  the  mainland  of  Italy,  we 
come  fo  Corsica  and  Elba.  The  serpentines  of  the  former 
island  have  long  been  known  to  geologists,  and  have  with- 
in the  last  few  years  been  especially  studied  by  liollande, 
•  Gastaldi's  letter  to  Zezl,  In  1878,  already  cited. 


1:       I'' 

mm 


I  ■;, 


h\ 


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.■«■  tiA.-'»:tm-x»L«fJ^.  -.H  >aB  .avtf ' 


rifniiififiifr 


"'li'^miffliiilJ 


474      THE  GEOLOGICAL  HISTORY  OP  SERPENTINES.  CS. 

Coquaiid,  Dieuiefait,  and  Lotti.  Coquand,  who  described 
the  serpentines  of  Corsica  in  1879,  and  who,  lilce  Hollaude, 
regards  them  as  eruptive,  supposes  them  to  be  in  part  very 
ancient,  and  in  pai't  tertiary,  since,  according  to  liim,  some 
of  them  overlie  the  nummulitic  beds.*  Fellati,  whose 
essay  we  have  already  cited,  refers  however  the  whob  of 
the  serpentines  of  this  island  to  a  pre-paleozoic  period, 
and  Dieuiefait,  who  described  these  rocks  in  1880,t  de- 
clares that  Coquand's  reference  of  the  serpentines  found 
near  Corte  to  the  tertiary  is  based  on  an  error  of  observa- 
tion. He  moreover  asserts  that  the  serpentines  of  Corsica 
are  stratified  sedimentary  rocks  belonging  to  a  single 
geological  horizon,  at  which  they  may  be  traced  continu- 
ously for  a  length  of  more  than  200  kilometres  from  Corso 
along  the  northeast  coast  of  the  island.  The  geological 
succession,  according  to  him,  is  as  follows :  —  1,  stratified 
protogine ;  2,  gneiss ;  3,  lustrous  schists ;  4,  saccharoidal 
limestones ;  5,  schists  more  or  less  talcose ;  6,  schists  en- 
closing sei'pentines  of  many  varieties;  7,  clay-slates;  8, 
black  limestones  with  carbonaceous  matter ;  9,  beds  often 
detrital ;  10,  infra-liassic  limestones,  with  Avicula  contorta. 
§  72.  Lotti,  who  has  since  studied  these  rocks,:^  con- 
firms fully  the  observations  of  Dieuiefait.  He  describes 
the  crystalline  limestones,  white  or  banded,  with  grayish, 
greenish,  or  lead-colored  talcose  or  silky  schists  (  holding 
a  mica,  sometimes  apparently  damourite  or  sericite),  in 
which  are  found  layers  of  serpentine.  The  serpentine 
itself  is  generally  scaly  in  texture  and  glassy,  but  granu- 
lar vai'ieties  are  met  with  including  veins  of  epidote, 
others  with  altered  crystals  of  olivine,  and  also  ophical- 
cites.  The  gneisses  beneath  the  serpentine  zone  pass  into 
quartzose  mica-schists,  often  including  almond-shaped 
masses  or  segregations  of  quartz  and  feldspar,  sometimes 

*  Coquand.     Bull.  Soc,  G^ol.  de  France  (3),  vil. 
t  Dieuiefait.  Coniptes  I'l-ndus  do  J'Acad,  des  Sciences,  xci.,  p.  1000. 
X  Lotti,  Appunti  Geologici  sulla  Corsica  ;  Boll,  del  Comitato  Geolo- 
gico,  anno  1883,  Nos.  3-4.  ' 


X.] 


EOCKS  OF  THE  ALPS. 


175 


with  large  plates  of  mica.  It  would  appear,  from  the 
descriptions  of  Lotti,  that  these  serpentines  of  Corsica 
belong  to  the  upper  horizon  defined  by  Gastaldi,  above 
the  recent  gneisses,  and  in  what  we  have  designated  as  the 
fourth  group  of  Alp'iue  crystalune  rocks.  (§69.)  The 
underlying  proto^fine  is,  according  to  Lot+^^i,  a  talcose 
gneiss. 

§  73.  The  resemblance  of  these  rocks  to  those  asso- 
ciated with  similar  serpentines  on  the  neighboring  island 
of  Elba  is  declared  by  Lotti  to  be  very  close.  There  also 
the  serpentinic  horizon  is  underlaid  by  gneisses  and  mica- 
schists,  as  in  Corsica.  He  concludes  witli  Gastaldi  that 
the  great  crystalline  zone  oi  the  Alps  is  connected  through 
the  Maritime  and  Ligurian  Alps  with  the  similar  rocks  of 
Corsica  and  Elba.  Resting  upon  the  ophioll^ic  strata  in 
Elba  are  found,  according  to  Lotti,  paleozoic  carbonaceous 
slates  containing  Orthoceras,  Cardiola,  Actinoirinus^  and 
probably  also  graptolites.  Lotti,  however,  while  he  asserts 
the  great  antiquity  of  all  of  the  serpentines  of  C'jrsica,  and 
part  of  those  of  Elba,  maintains  the  existence  in  the  latter 
island  of  other  serpentines,  which,  like  those  of  Tuscany, 
he  refers  to  the  eocene  period. 

A  similar  question  is  raised  with  regard  to  the  granites 
of  the  two  islands.  Thus  Pare  to,  who  regarded  as  ancient, 
or  at  any  rate  pre-triassic,  the  granites  of  Corsica,  admit- 
ted for  the  granites  of  Elba,  Monte  Cristo,  and  Giglio  a 
post-eocene  age,  a  view  which  is  also  sustained  by  Lotti, 
while  De  Stefani,  on  the  other  hand,  assigns  the  Elban 
granites  to  prr-triassic  time.  I  can  scarcely  doubt  that  all 
of  these  granites,  as  well  as  tlie  ophiolites  both  of  the 
various  islands  and  the  mainland,  will  be  found,  as  main- 
tained by  Gastaldi,  of  pre-paleozoic  age. 

§  74.  If  we  turn  to  the  island  of  Sardinia  wt  find  a 
series  of  pre-Cambrian  .crybtalline  schists,  said  to  consist, 
in  their  upper  portions,  of  argillites,  sometimes  talcose, 
sandstones,  crystalline  limestones,  and  dolomites.  These, 
which  are  referred  by  Bornemann  to  thf<  Huronian  or 


ii 


470      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X. 


I   j 


i  ;• 


n> 


ii, 


^:!iii' 


pietre-verdi  zone  of  the  Alps,  are  overlaid,  as  was  first 
shown  by  De  la  Marmora,  by  a  series  of  uii crystalline 
limestones,  shales,  and  sandstones,  containing  an  abundant 
lower  paleozoic  fauna.*  Of  this,  the  upper  Cambrian 
(Ordovician)t  forms  were  long  since  described  by  Mene- 
ghini.  The  subsequent  studies  of  Bornemann,  in  1880, 
showed  at  the  base  of  the  series  a  zone  marked  by  Para- 
doxides,  Conocephalites,  Archeoci/athus,  etc.,  wliicli  have 
also  been  examined  by  Meneghini,  and  establish  the 
existence  of  a  Lower  Cambrian  horizon.  The  writer  had, 
in  1881,  the  pleasuire  of  examining  at  Bologna,  in  company 
with  James  Hall,  a  collection  of  these  fossils.  Above  the 
Ordovician  beds  in  Sardinia  is  found  a  great  mass  of 
limestone,  of  undetermined  age,  remarkable  for  its  beds 
and  included  masses  of  lead,  silver,  and  zinc-ores. 

§  75.  We  have  now  shown  that  these  crystalline  rocks, 
which,  in  parts  of  the  mainland,  are  directly  succeeded 
by  tertiary  sediments,  are  in  different  areas  overlaid  by 
various  subdivisions  of  the  mesozoic,  and  finally  by  car- 
boniferous, Ordovician,  and  Cambrian  sediments,  thus  dis- 
proving the  view  of  the  older  geologists,  who  assigned  to 
these  same  crystalline  recks  a  paleozoic  or  a  mesozoic  age. 
It  is  instructive  to  mark  the  steps  by  which  this  view 
has,  in  the  process  of  investigation,  been  left  behind.  In 
Neri's  section  the  older  gneiss  and  the  pietre  verdi  proper 
are  called  azoic  or  protozoic,  but  the  recent  gneiss  is  con- 
jectured to  be  paleozoic.  Lory,  however,  included  the 
latter  in  the  primitive  series,  but  claimed  the  lustrous 
schists  as  altered  trias,  while  later,  Gxstaldi,  and  with 
him  Favre,  placed  even  these  in  the  paleozoic,  until  at 
last  we  find  Gastaldi  adopting  the  conclusion  first  put 
forward  by  the  present  writer  in  1872,  that  the  whole  of 
these  crystalline  rocks  are  to  be  referred  to  pre-Can\brian 
time. 

*  Bornemann,  sur  les  formations  stratifides  anclennes  tie  la  Sardalgne. 
Comptes  Ilendus  du  Congros  Gcol.  Inter,  de  Bologne,  pp.  221-232. 
t  Scepo^t,  Essay  XL,  §  17. 


X.] 


EOCKa  OF  THE  ALPS. 


477 


§  76.  The  Gtory  of  the  crystalline  marbles  of  Carrara, 
now  included  in  this  series,  is  not  less  instructive.  They 
were  regarded  as  eruptive  by  Savi,  who  taught  that  dolo- 
mites and  limestones  had  been  poured  out  in  a  fused  state, 
alike  in  secondary  and  in  tertiary  times,*  and  even  indicated 
what  he  supposed  to  be  centres  of  eruption.  The  marbles 
of  Carrara,  with  their  associated  schists,  have  since  been 
called  cretaceous,  liassic,  rhaetic,  infra-carboniferous,  and 
pre-paleozoic.f  They  were  in  1874,  in  the  second  part  of 
Gastaldi's  Studii,  included  in  the  rocks  of  the  pietre-verdi 
zone,  the  term  heiu^.  then  used  in  its  larger  sense,  as  em- 
bracing not  only  tL>  urue  pietre  verdi,  but  the  whole  crys- 
talline series  above  the  ancient  gneiss. 

§  77.  This  was  also  clearly  stated  by  Jervis,  in  his  elab- 
orate work  on  the  mineral  resources  of  Italy,J  a  veritable 
treasury  of  information,  most  carefully  and  systematically 
arranged.  In  his  first  volume,  in  a  tabular  view  of  the 
geology  of  the  Alps,  he  had  already  adopted  the  views  of 
Gastaldi,  and  placed  the  whole  of  the  crystalline  stratified 
rocks  above  the  ancient  gneisses  in  a  "pre-paleozoic  group," 
which  he  regarded  as  synonymous  with  the  pietre-verdi 
zone.  In  his  second  volume,  in  a  similar  tabular  view  of 
the  geology  of  the  Apennines  and  the  adjacent  islands,  he 
further  insists  upon  the  same  view,  and  puts  above  the 
ancient  gneiss,  in  what  he  calls  the  pre-paleozoic  period, 
the  great  series  of  "  stratified  azoic  rocks,"  including  not 
only  the  ophiolites,  and  the  recent  gneisses  and  other 
crystalline  schists,  but  the  saccharoidal  and  compact  mar- 
bles of  the  Apuan  Alps.  (Loc.  cit.,  p.  9.)  It  is  to  be 
remarked,  as  shown  both  bv  Jervis  and  Gastaldi,  that 
this  great  younger  crystalline  series  is  the  metalliferous 

*  Boue,  Guide  du  g^ologue  voyageur,  II.,  168.  For  the  views  of 
others  as  to  the  eruptive  origin  of  crystalline  limestones,  see  my  Chemical 
and  Geological  Essays,  p.  218,  and  oii^e,  pp.  00,  01,  and  228. 

t  For  a  jiotice  of  some  of  the  various  views  which  have'lioon  put  for- 
ward with  regard  to  the  age  of  these  marbles,  see  Lebour  in  the  Geologi- 
cal Magazine  for  1876,  pp.  287  and  .383. 

X  1  'i "esori  Sotteranei  del'  Italia,  3  vols.  Svo,  Turin,  1878-1881. 


ill 


478      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X. 


r     1- 


tone  of  Italy,  containing  much  cupriferous  and  niccolifer- 
0U8  pyrites,  in  veins  and  interstratified  beds,  together 
with  crystalline  iron-ores,  lead,  zinc,  and  gold. 

§  78.  With  the  general  succession  of  the  Alnine  rocks 
already  given,  we  may  compare  the  observations  of  Tara- 
nielli  in  the  Valtelline,  where  he  describes  the  ophiolites 
as  lying  below  a  great  gneissic  and  granitic  series,  from 
which  they  are  separated  by  a  garnetiferous  hornblendic 
rock  and  saccharoidal  limestones.  The  lowest  division 
in  the  series,  as  observed  in  the  Valtelline,  is,  according  to 
Taramelli,  a  quartzose  talc-schist,  upon  which  reposes  tu: 
serpentine  in  heavy  continuous  beds,  having  all  the 
appearance  of  a  stratified  rock,  followed  by  potstone,  that 
is  to  say,  steatite  or  chlorite.  To  this  succeed,  in  ascend- 
ing order,  hornblendic  and  epidotic  rocks,  associated  with 
crystalline  limestones,  often  talciferous ;  then  schistose 
amphibolite,  talcce  gneiss,  talc-schists,  and  eclogite,  and 
finally  a  coarsely  crystalline  glandular  gneiss,  itself  over- 
laid by  granitic  and  associated  hornblendic  rocks.  This 
apparent  reversal  of  the  succession  as  defined  by  Gastaldi 
and  others,  suggests  the  probability  that  we  may  have  in 
the  Valtelline  an  overturn  of  the  strata,  such  as  is  well 
known  in  many  parts  of  the  Alps  and  elsewhere,  placing 
the  more  ancient  rocks  above  the  younger  ones.* 

§  79.  It  is  here  the  place  to  notice  the  mode  of  occur- 
rence of  the  serpentines  which,  in  Saxony,  are  found 
interstratified  in  the  granulite  series  of  the  Mittelgebirge. 
The  granulite  proper  may  be  described  as  a  fine-grained, 
gray,  laminated  binary  gneiss,  consisting  essentially  of 
orthoclase  and  quartz,  but  often  containing  garnet,  and 
sometimes  cyanite  and  andalusite.  By  an  admixture  of 
mica,  it  passes,  through  ordinary  gneiss,  into  mica-scbists, 
which  are  abundant  in  the  series.  In  it  are  also  inter- 
stratified diohroite-gneiss,  sometimes  in  great  beds,  and  a 
greenish  hornblendic  gneiss,  as  well  as  the  so-called  gab- 
broe  of  the  region  (like  that  of  Neurode).  These  occur 
*  Boll.  Soc.  Geologica  Italiana,  I.,  p.  14. 


.' 


X.] 


EOCKS   OF  SAXONY. 


479 


in  larger  or  smaller  lenticular  interstratified  masses,  to 
•wliiuh  the  distribution  of  the  diallage  in  a  granular  labra- 
dorite  base  gives  a  well  defined  gneissoid  structure.  In 
this  same  series,  tlie  serpentine  is  found  in  interstratified 
beds,  occasionally  garnetiferous,  and  sometimes  associated 
with  Iherzolite. 

§  80.  I  have  not  seen  these  rocks  on  the  ground,  but 
have  examined  a  large  collection  of  them  in  Leipzig,  with 
the  assistance  of  my  friend.  Dr.  Hermann  Credner,  and 
was  struck  with  their  close  resemblances  to  the  rocks  with 
which  I  am  familiar  in  the  newer  or  Montalban  series  of 
gneisses  and  mica-schists  throughout  the  Atlantic  belt  of 
North  America.  The  muscovite-gneisses  of  the  Erzgebirge, 
with  their  occr  ^onal  layers  of  limestone  and  of  hornblende- 
rock,  and  their  intercalated  and  overlying  mica-schists,  I 
also  refer  to  the  same  general  horizon.  It  is  in  these,  it 
will  be  remembered,  that  are  found  the  abundant  con- 
glomerate beds  described  by  Sauer,  the  pebbles  in  which 
consist  chiefly  of  varieties  of  granitoid  gneiss,  resembling 
closely  those  cf  the  ancient  gneiss  of  the  Alps  (Biellese) 
and  the  Laurentian  gneiss  of  North  America.  These  are, 
however,  as  I  have  seen,  accompanied  by  pebbles  of  crys- 
talline limestone.*  Mention  should  also  be  made,  in  this 
connection,  of  the  existence  of  similar  conglomerates  in 
Sweden,  at  Soljoarne,  where  pebbles  of  ancient  gneiss  and 
granite  are  found,  at  several  points,  imbedded  in  fine-grained 
schistose  gneiss,  in  calcareous  mica-schist,  and  also  in  a 
red  halleflinta,  the  strata  of  all  of  which  are  shown  to 
rest  unconformably  upon  the  older  granitoid  gneiss.f 

§  81.  It  will  be  remembered  by  students  in  geology 
that  in  1870  the  present  writer  announced  his  conclusion 
that  there  exists  in  North  America,  besides  the  Lauren- 
tian gneisses,  "  a  great  series  of  crystalline  schists,  includ- 

*  Zeitschrift  f.  d.  ges.  Naturwiss,  Band  liii. ;  also,  Geol.  Mag.,  January, 
1882,  and  Bull.  Soc.  G^ol.  de  Fr.,  x.,  20;  also,  Amer.  Jour.  Science  (3), 
xxvi.,  p.  197  ;  and  ante,  p.  255. 

t  Hummel.  Cm  Sveriges  Lagrade  Urberg,  etc.,  Stockholm,  1875, 
p.  30. 


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THE  GEOLOGICAL  HlSTOllY  OP   SERPENTINES. 


[X. 


ing  mica-schists,  staurolite,  and  chiastolite-schists,  with 
quartzose  and  hornblendic  rocks,  and  some  limestones, 
the  whi  le  associated  with  great  masses  of  fine-grained 
gneisses,  the  so-called  granites  of  many  parts  of  New 
England."  *  These  rocks  were  especially  indicated  as  oc- 
curring in  the  White  Mountains  of  New  Hampshire,  but 
were  also  said  to  be  found  to  the  northwest  of  Lake  Su- 
perior, as  well  as  in  Ontario  and  in  Newfoundland,  in 
which  last  two  regions  they  were  believed  to  rest  uncon- 
formably  ujjon  the  Laurentian  gneiss.  In  both  of  these 
latter  localities,  there  were  provisionally  associated  with 
this  group  some  higher  limestones,  with  crystalline  schists, 
and  for  the  whole  the  name  of  Terranovan  was  suggested. 

§  82.  In  the  following  year,  1871,  in  an  address  before 
the  American  Association  for  the  Advancement  of  Sci- 
ence, these  rocks  were  farther  noticed,  under  the  name  of 
the  White  Mountain  series.  The  higher  limestones  and 
schists  (which  were  not  found  on  the  geological  section 
then  described)  were,  however,  excluded.  This  great 
series  of  younger  gneisses  and  mica-schists  was  then  as- 
signed to  a  horizon  above  the  Huronian,  and  as  a  distinct- 
ive name  was  desirable  for  o  series  so  conspicuous  in 
American  geology,  that  of  Montalban  (from  the  latinized 
name  of  the  White  Mountains)  was  proposed  in  the  same 
year.f  It  was  at  the  same  time  shown  that  the  view  held 
by  most  American  geologists,  that  these  rocks  were  altered 
paleozoic  strata,  was  untenable,  and  that  they  were  to  be 
regarded  as  pre-paleozoic.  At  a  later  period,  the  higher 
limestones  and  schists,  at  first  associated  with  these  newer 
gneisses  and  mica-schists,  were  referred  to  the  Lower  Ta- 
conic  of  Emmons  —  the  Taconian  series.J 

When,  in  1870  and  1871, 1  thus  attempted  to  subdivide 

*  Amer.  Jour.  Science  (3),  1,  85. 

t  Proc.  Amer.  Assoc.  Adv.  Science,  1871,  p.  6;  also  Chdm.  and  Geo!. 
Essays,  pp.  194,  244,  282;  Das  Ausland,  Dec.  25,  1871,  p.  1288,  and  Azoic 
Rocks,  p.  181. 

t  Azoic  Rocks,  pp.  201-211,  215. 


0& 

},  with 
jstones, 
crrained 
°i  New 
jtl  as  oc- 
lire,  but 
:^ake  Sii- 
Uand,  in 
t  iincon- 
of  these 
ited  with 
\e  schists, 
mggested. 
ess  before 
nt  of  Sei- 
le  name  of 
itones  and 
cal  section 
This   great 
'as  then  as- 
,  a  distinct- 
ipicuous  in 
lie  latinized 
Sn  the  same 
e  view  held 
;ere  altered 
were  to  be 
,  the  higher 
[these  newer 
Lower  Ta- 

bo  subdivide 


jLita.  and  Geol. 
|l288,  and  Azoic 


X.] 


ROCKS  OF  THE  ALPS. 


481 


the  crystalline  schists  above  the  ancient  gneiss  of  North 
America,  and  to  define,  above  the  liuronian,  a  younger 
series  of  gneibocs  with  niica-shists,  I  was  not  aware  that 
Von  Ilauer  liad  already  been  led  by  his  studies  to  similar 
conclusions  for  the  Eastern  Alps,  and  had  discovered 
above  the  great  pietre-verdi  zone,  a  series  of  gneisses  with 
micaceous  schists,  as  indicated  in  divisions  5  and  6  of  his 
section  (§  60).  Gastaldi,  in  1871,  and  for  years  after,  in- 
cluded these,  with  all  the  crystalline  schists  found  above 
the  ancient  or  central  gneiss,  in  one  great  group  of  newer 
schists,  which  he  assimilated  to  the  Huronian.  In  review- 
ing this  subject,  in  1878,*  I  pointed  out  that  the  upper- 
most crystalline  schists  of  the  Western  Alps  should  be 
separated  from  the  Huronian,  and  compared  them  with 
the  Taconian,  while  I  noted  the  fact  "  that  gneisses  and 
mica-schists  similar  to  those  of  the  Montalban  are  found 
in  many  parts  of  the  Alps."  It  was  not,  however,  until 
after  my  studies  among  these  rocks  in  1881,  that  I  referred 
the  newer  gneissic  series  of  that  region  to  the  Montalban, 
for  the  two-fold  reason  that  it  occupies  a  similar  strati- 
graphical  horizon  and  is  lithologically  indistinguishable 
from  it. 

§  83.  Not  less  important  in  this  connection  is  the  suc- 
cession of  crystalline  rocks  in  Eastern  Bavaria,  which 
may  be  compared  with  those  of  Saxony.  We  have,  in 
ascending  order,  according  to  GUmbel,  first,  the  red  or 
variegated  gneiss,  called  by  him  Bojian,  Avhich  is  followed 
immediately  by  the  newer  gray  or  Hercynii  -  gneiss,  his 
second  division,  and  by  a  third,  the  Hercyniun  mica-schist 
series,  occasionally  hornblen'^'ic.  To  this  succeeds,  in  the 
fourth  place,  the  Hercynian  primitive  clay-slate  series, 
which  is  immediately  overlaid  by  Lower  Cambrian  fossil- 
iferous  rocks.  This  primitive  clay-slate  series  contains 
interstratified  beds  of  limestone,  sometimes  doloniitic,  at- 
taining in  places  a  thickness  of  350  feet,  and  associated 
with  siderite,  which  gives  rise  by  epigenesis  to  valuable 

*  Azoic  liocks,  p.  245. 


I 


'If 


ni^eaMSi 


S: 


t 


482      THE  GEOLOGICAL  HISTOKY  OF   SERrENTlNES. 


[X. 


> 


'Mi 


deposits  of  limonite  along  its  outcrop.  With  these  lime- 
stones are  found  varieties  of  hornblende  and  serpentine, 
accompanying  which  is  the  Eozodn  Bavaricum  of  Giimbel. 
§  84.  The  Ilcrcynian  gneiss  is  described  by  Giimbel  as 
including  nnicli  gray  quartzose  and  micaceous  gneiss,  with 
frequent  beds  of  dichroite-gneiss,  granulite,  serpentine, 
hornblendic  schists,  and  crystalline  linipstones.  With 
these  are  associated  Eozoon  Canadense-,  from  which  Giim- 
bel supposed  this  upper  gneissic  series  to  represent  the 
Laurentian,  a  view  which  was  accepted  by  the  present 
writer,  when,  in  1866,  he  translated  and  edited  Giimbel's 
pai)er  *  for  the  Canadian  Naturalist,  and  has  since  been  ex- 
pressed by  him  elsewhere ;  coupled  with  the  suggestion 
that  the  Bojian  might  correspond  to  the  Ottawa  gneiss 
which  underlies  the  Grenville  series,  the  typical  Lauren- 
tian (Lower  Laurentian)  of  the  Canadian  survey.  We 
are  not,  however,  as  yet  prepared  to  recognize  a  subdivis- 
ion in  the  older  gneisses  of  continental  Europe,  and 
meanwhile  the  analogies  between  the  great  Hercynian 
gneiss  and  mica-schist  series  combined,  and  the  younger 
gneisses  and  mica-schists  of  Saxonj''  and  of  the  Alps,  lead 
us  to  refer  what  Giimbel  has  described  as  the  newer  gneiss 
series  of  Bodenmais  and  the  Danube,  to  the  same  horizon 
as  the  younger  gneisses  of  Gastaldi  and  Von  Hauer, —  the 
Montalban  series,  which  in  eastern  Bavaria  would  seem, 
as  in  the  Simplon,  to  rest  directly  upon  the  older  gneiss, 
the  Huronian  being  absent.  The  Hercynian  clay-slate 
series,  with  its  crystalline  limestones,  may  correspond  to  the 
fourth  group  of  the  Alpine  rocks,  the  argillo-talcose  scliists, 
which  we  have  compared  with  the  American  Taconian. 

V.  —  THE  SERPENTINES  OF  ITALY. 

§  85.  Returning  to  the  Italian  Alps,  we  have  now  to 
call  attention  to  a  very  important  conclusioi  reached  by 

*  Giimbel,  tjber  der  Vorkommen  von  Eozoon  in  dera  Ostbayerischen 
Urgeblrge,  Miinchen  Akad.  Sitzungsb.,  1866  (l),pp.  25-70;  also  Can.  Nat- 
uralist, iii.,  1868,  pp.  81-101. 


X.1 

SERPENTINES   OF  ITALY. 

483 

\ 

Gastaldi, 

with 

regard  to  the 

geographical  relations 

of  the 

pietre-verdi  zone  ;  using  tho 

term  in  its 

larger  sense,  as 

embracing  all  the  newer  crystalline  rocks,  or  those  above 
the  ancient  gneiss.  In  1871,  in  the  first  part  of  his 
memoir  on  the  Western  Alps,  he  declared  it  ;8  liis  opinion 
that  "  all  the  serpentinic  masses  of  the  Tuscan  and  Ligu- 
rian  Apennines,  and  the  serpentines,  ophicalcites,  sacchar- 
oidal  limestones  and  granites  of  Calabria,  are  but  a  pro- 
longation of  this  zone."  In  this  were  included,  as  we 
have  already  seen,  tlie  Apuan  Alps,  and,  farther  westward, 
a  large  part  of  the  Maritime  Alps.  In  support  of  these 
views  he  pointed  out  the  mineralogical  identity  of  the 
ophiolites  and  other  crystalline  rocks  in  the  Alps  and  the 
Apennines.  To  the  same  horizon  he  also  referred  the  so- 
called  ophitic  terrane  of  the  Pyrennees. 

§  86.  Gastaldi  further  called  attention  to  the  fact  that 
ophiolitic  rocks  often  appear  in  the  form  of  isolated  peaks 
or  hills,  for  the  reason  that  the  accompanying  crystalline 
schists  and  calcareous  rocks,  opposing  less  resistance,  have 
been  removed  by  decay  and  erosion,  adducing  many  in- 
stances in  support  of  this  among  the  Alps.  This  being 
the  case,  he  adds,  we  are  not  to  be  surprised  when  in  the 
Apennines  we  find  isolated  masses  of  ophiolite  rising  out 
of  the  midst  of  surrounding  Jurassic,  cretaceous,  or  ter- 
tiary strata,  which  conceal  the  rocks  that  accompany  the 
ophiolite.  Thus  it  is,  he  adds,  that  "the  notion  has  arisen 
in  the  Apennines  that  the  serpentines,  diorites,  etc.,  are 
always  eruptive  rocks."  They  are,  in  his  view,  to  make 
use  of  the  happy  expression  of  Roland  Irving  in  describ- 
ing a  similar  occurrence,  "protruding,  but  not  extruded." 
These  views  were  reiterated  by  Gastaldi  in  his  letter  to 
Zezi  in  1876,  when  he  asserted  that  the  skeleton  of  the 
Apennines  is  a  continuation  of  that  of  the  Alps,  and  that 
the  crystalline  rocks  of  the  Apennines  are  Alpine  rocks. 
From  the  summit  of  Mont  Blanc,  he  declared,  they  may 
be  followed,  more  or  less  concealed  by  overlying  strata  of 
more  recent  date,  to  the  Danube,  to  the  plains  of  France, 


484     THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  Pf. 


0'M 


f-,i' 


i!,'l 


to  the  Mediterranean,  and  along  the  peninsula  which  sepa- 
rates this  sea  from  the  Adriatic  ;  *  assertions  which  he  sup- 
ported in  1878  by  many  detailed  observations,  to  be 
noticed  farther  on. 

§  87.  These  bold  generalizations  of  Gastaldi  have  met 
with  but  partial  acceptance  in  Italy,  as  may  be  seen  by  tlie 
discussions  in  1881,  and  the  publications  of  the  11.  Comi- 
tato  Geologic©  and  the  Societti  Geologica  Italiana  in  1881 
and  1882,  already  referred  to  in  §  43.  Pellati,  in  his  sum- 
mary, declares  that  the  views  of  Gastaldi  as  to  the  anti- 
quity of  the  Alpine  pietre  verdi  are  confirmed  by  the  work 
of  Baretti  and  of  Taramelli,  the  latter  of  whom  clearly 
shows  that  the  view,  entertained  by  so  many,  that  these 
rocks  are  carboniferous  or  triassic,  is  inadmissible.  Hence, 
these  ancient  serpentines  are  by  Pellati  designated  as  pre- 
paleozoic  (eozoic).  This  view  he  extends  to  all  the 
ophiolitic  masses  situated  in  the  Alps,  to  those  of  Calabria, 
and  also  to  those  of  the  Apennines  west  of  the  meridian 
of  Genoa,  those  to  the  east  of  this  meridian  being  in- 
cluded in  the  eocene.     (§  47.) 

§  88.  Regarding  the  so-called  eocene  serpentine,  and 
its  associated  rocks,  Pellati  observes,  "  as  to  its  composi- 
tion, it  differs  but  little  from  the  older  serpentine,  the 
differences  remarked  being  principally  in  a  structure  or- 
dinarily less  schistose,  and  in  a  greater  frequency  of  sub- 
ordinate ophiolitic  rocks ;  euphotides,  eurites,  diorites,  va- 
riolites,  ophicalcites,  etc.,  more  or  less  decomposed.  The 
masses  of  proper  serpentine  are  ordinarily  more  scattered, 
and  of  smaller  dimensions,  having  almost  always  gabbros 
and  beds  of  phthanite  and  jasper  around  them."  Cossa, 
it  is  true,  has  remarked  in  the  specimens  examined  by  him 
that  the  mineral  species  bastite  is  more  common  in  the 
eocene,  or  Apenniiie,  than  in  the  eozoic,  or  Alpine,  ser- 
pentines, but,  with  this  possible  exception,  the  mineralogi- 
cal  and  lithological  associations  of  the  two  are  apparently 
identical.  In  fact,  Pellati  admits  that  it  is  in  some  cases 
*  See  the  author,  on  Azoic  Eocks,  p.  245. 


I.      Pf- 

ell  sepa- 

he  sup- 

^  to  be 

lave  met 
)u  by  tbe 
R.  Coini- 
a  in  1881 
1  liis  sum- 
tbe  auti- 
tbe  work 
m  clearly 
tliat  these 
5.     Hence, 
ted  as  pre- 
to  all  the 
,f  Calabria, 
le  meridian 
L  being  in- 


X.] 


SERPENTINES   OF   ITALY. 


485 


difficult,  if  not  impossible,  to  distinguish  between  them. 
Within  the  great  basin  lying  to  the  east  of  the  meridian 
of  Genoa,  and  embracing,  as  we  have  seen,  the  so-called 
tertiary  serpentines,  we  are  informed  by  him  that  ''the 
paleozoic  and  mesozoic  rocks  are  generally  very  thin,  and 
often  are  entirely  absent,  in  which  case  the  floor  of  jiietre 
verdi,  or  greenstones,  is  directly  overlaid  by  the  tertiary, 
and  in  fact  by  the  very  eocene  which  includes  the  younger 
serpentines.     This  is  the  case  in  the  vicinity  of  Genoa, 
upon  thfc  right  bank  of  the  Polcevera,  where  the  green- 
stones come   in  direct  contact  with  the   shales  and   the 
limestones  of   the   npi)er   eocene,   and   here   it   becomes 
doubtful  whether,  along  this  line  of  outcrop,  por.ions  of 
tertiary  ophiolites  are  not  mixed  and   confounded  with 
others  of  the  pre-paleozoic  period."     These  supposed  ter- 
tiary ophiolites  "  have  a  very  great  resemblance  to  those 
of  the  eocene  of  eastern  Liguria,  and  present,  moreover, 
a  large  development  of  the  rocks  which  Issel  has  desig- 
nated as  amphimorphic  (§  92).     Thus,  near  Pietra  Lavez- 
zara,  for  example,  ophicalcites  are  exploited  which  are 
precisely  like  the  green  marbles  of  Levanto.    In  this  same 
locality,  moreover,  argillites  having  the  aspect  of  those  (jf 
the  eocene  appear  to  dip  beneath  the  ophiolites."      In 
support  of  the  belief  that  these  seemingly  tertiary  ophio- 
lites are  really  eozoic,  however,  W3  are  told  that  their 
outcrops  present  lines  of  continuity,  connecting  these  ser- 
pentines with  those  of   which   the   eozoic   origin  is   un- 
doubted.   We  have  seen  (§  41)  that  Professor  Bonney,  in 
his  studies  of  the  serpentines  of  Italy,  fails  to  remark  iiny 
distinction  between  the  serpentines  thus  separated  by  the 
Italian  geologists,  since  he  describes  as  similar,  both  in 
mineralogical  characters  and  in  geognostical  relations,  the 
ophiolites  lying  to  the  west  and  those  lying  to  the  east  of 
tlie  meridian  of  Genoa.     I  shall,  farther  on,  have  occasion 
to  refer  to  my  own  observations  of  some  of  these  localities. 
§  89.   The  older  school  of  Italian  geologists,  as  already 
noticed,  supposed  the  serpentines  to  have  been  erupted, 


1. 


''"PI 


i 


m 

Ml 

m 


48(3      THE  GEOLOGICAL  HISTORY  OF  SEllPENTINES. 


[X. 


|l";<« 


r- ,.,.' 


:i 


liUe  biisalts,  at  difToroiit  ^eolo^iciil  periods,  and  applied 
tliis  view,  not  only  to  thoso  wiiicli  are  evidently  included 
among  eozoic  rocks,  but  also  to  thoso  which  rise  among  the 
teitiiiry  deposits.  Tiie  study  of  tiie  ophiolitic  masses  of 
eastern  Liguria  and  of  Tuscany,  induced  the  earlier  geolo- 
gists, like  Savi,  Pilla,  and  I'areto,  to  refer  them  to  various 
ages  between  the  cretaceous  and  the  pliocene,  but  more 
recent  observers  have  been  led  to  include  all  of  these 
ophiolites  in  the  upjjcr  eocene.  This  view  was  first 
advanced  for  those  of  the  mainland  of  Tuscany  by  De 
Stefani,  in  1878,  and  has  since  been  maintained  by  Lotti, 
Taramelli,  Issel,  Muzzuoli,  and  (!!apacci,  among  others. 
The  horizon  in  the  ui)per  eocene  to  which  these  observers 
refer  the  serpentines  in  question,  consists  of  argillaceous 
and  marly  shales,  alternating  with  beds  of  limestone  and 
sandstone,  and  is  below  the  argillaceous  limestones  with 
fucoids  and  nemertilites,  but  above  the  sandstone  known 
as  macigno,  which  is  found  at  the  base  of  the  eocene  in 
Liguria. 

§  90.  As  regards  the  origin  of  serpentines,  Peliati  re- 
marks that  the  recent  studies  of  Italian  geologists  have 
led  to  hypotheses  which  ditfer  widely  from  those  formerly 
received,  according  to  which  serpentines  were  regarded 
as  plutonic  or  eruptive,  having  come  to  the  surface  after 
the  manner  of  volcanic  lavas,  or,  at  least,  like  certain 
massive  trachytes,  in  a  pasty  state,  or  one  of  igneous  semi- 
fluidity.  Gastaldi,  he  adds,  "from  his  studies  of  the  an- 
cient serpentines  of  the  Alps,  regarded  them,  however,  as 
sedimentary  rocks,  modified  by  subsequent  hydrothermal 
actions  operating  at  great  depths  in  the  earth."  He 
compared  their  formation  to  that  of  the  accompanying 
gneisses,  mica-schists,  chlorite-schists,  crystalline  lime- 
stones, diorites,  and  even  the  granites,  syenites,  and  por- 
phyries of  the  Alps,  to  all  of  which  he  ascribed  an  aqueous 


origin. 


§  91.   This  hypothesis  has  not,  however,  been  favorably 
received  as  an  explanation  of  the  origin  of  the  so-called 


X*) 


SEUPENT1NE8  OF   ITALY. 


487 


toi'tiiiry  opliiolitoH  of  tlio  Tuscan  iuul  Li<ifti"''Mi  Apciinliics. 
Tuniiiiclli,  IVoiii  liis  .studies  of  l\\o.  HLTpfuli  of  tin;  Viilloy 
of  tlio  TivWhiii,  (locliinMl  that  ucitlitu-  the  ii  j  iuoiitioiiod 
view  oftlioir  ij^ueous  cruptivo  ori^u,  nor  tl«  t  uuiiutaiiiod 
by  Gastaldi,  could  be  conciliated  with  the;  facts  of  the 
stratiform  and  lenticular  arrangiunent  of  the  nuissos  of 
serpentine,  the  want  of  evidences  of  alteration  in  the 
interslratilicd  layers  of  limestones  and  argillitos,  and  the 
absence  of  ophiolitic  dikes  in  these  same  nxiks.  He  was 
thus  led  to  conclude  that  the  ophiolites  had  been  formed 
in  the  midst  of  the  tertiary  sediments  by  contempora- 
neous submarine  eru[)tions  of  niaj^nesian  and  feldspathie 
inaj^mas,  and  that  the  euphotides  and  other  associated 
ophiolitic  rocks  had  probably  resulted  from  subseciuent 
crystal logenic  concentrations,  which  took  place  in  these 
erupted  magmas.  Capacci,  from  his  investigiition  of 
the  ophiolitic  mass  of  Monteferrato  in  Prato,  advanced  a 
similar  view,  supplemented  by  the  hy])othesis  of  thernuil 
waters  accom[)anying  the  eruption  of  the  magnesian 
magma  or  succeeding  it. 

§  92.  Issel  and  Mazzuoli,  from  their  joint  studies  in 
eastern  Liguria,  have  formubited,  more  at  length,  an 
analogous  hypothesis  to  exi)lain  alike  the  origin  of  the 
serpentines,  and  of  the  rocks  there  intimately  associated 
with  them,  such  as  t^'orltes,  aphanites,  variolites,  and 
euphotides.  To  these  ■  ley  give  the  general  designation 
of  amphimorphio  rocks,  luggested  by  the  conception  that 
they  have  had  a  two-fold  origin,  and  have  resulted  from 
mixtures  and  combinations  of  slowly  deposited  argilla- 
ceous materials  of  mechanical  origin  with  elements  brought 
in  by  abundant  thermal  springs  through  a  long  period,  both 
during  and  after  the  eruption  of  the  serpentinous  magma. 
This  latter,  they  suppose,  was  a  phenomenon  of  short 
duration,  almost  instantaneous,  while  the  formation  of  the 
euphotides  and  other  amphimorphic  rocks  was  a  slow  pro- 
cess. Nor  is  this  the  only  effect  ascribed  to  the  hypothet- 
ical thermal  springs,  which  our  authors  suppose  to  have 


iKii 


488      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X. 


I 


M 


'Ml 


acted  upon  pre-existing  continuous  calcareous  and  argilla- 
ceous strata,  penetrating  them  with  waters  holding  in 
solution  silica  and  oxyds  of  iron  and  manganese,  and 
converting  them  to  jaspers,  phthanites,  or  silicious  slates, 
or  to  certain  ill  defined  silico-argillaceous  or  calcareous 
rocks  which  Issel  has  called  hypophthanites. 

§  93.  The  serpentines  themselves  having  nothing  in 
common  with  the  argillites,  sandstones,  and  limestones 
among  which  they  are  found,  these  observers  have  imag- 
ined that,  after  the  deposition  of  the  eocene  sandstone, 
great  eruptions  of  a  hot  inipali)able  mud,  consisthig  prin- 
cipally of  silicates  of  magnesia  and  iron  generated  by 
some  unexplained  process,  were  poured  out  from  sub- 
marine fissures  in  the  earth's  crust,  were  spread  over  the 
bottom  of  the  sea,  filling  depressions  therein,  and  were 
subsequently  changed  into  serpentine.  Thus,  by  this 
hypothesis,  "the  serpentines  are  considered  as  eruptive 
without  being  truly  igneous,  inasmuch  as  they  do  not 
contain  in  their  composition  any  mineral  which  has  been 
submitted  to  igneous  fusion,  and  do  not  show,  at  their 
contact  with  the  sediments  adjoining,  any  metamorphic 
product  due  to  a  very  elevated  temperature.  In  order, 
however,  to  explain  the  slight  traces  of  contact-metamor- 
phism  which  are  especially  seen  in  enclosed  masses  of 
limestones,  they  admit  that  at  the  moment  of  its  emission 
the  magma  may  have  had  a  temperature  of  several  hun- 
dred degrees.  As  to  the  ophicalcites,  which  are  often 
found  at  the  contact  of  the  serpentine  with  the  sedimen- 
tary rocks,  and  sometimes  even  at  a  certain  distance  from 
these,  their  formation  is  attributed  to  the  cementation  of 
serpentine  breccias  by  calcareous  waters  discharged  in 
the  last  phase  of  the  eruptive  period." 

§  94,  Pellati  sets  forth,  with  wise  caution,  the  preced- 
ing hypothesis  as  the  one  suggested  by  the  observers 
already  named  for  the  Apennine  ophiolites,  and  adds  that 
it  might  ])erhaps  be  also  extended  to  the  ophiolites  of 
admitted  eozoic  age,  which,  he  says,  "so  far  as  we  know 


m 


SERPENTINES   OF  ITALY. 


489 


at  present,  consist  essentially  of  rocks  of  tlie  same  nature 
and  the  same  composition,"  He  insists,  moreover,  upon 
farther  researches,  even  in  the  case  of  the  supposed  eocene 
serpentines,  and  upon  the  importance  of  discoveiing  the 
centres  of  eruption  through  the  pre-existing  strata,  "or, 
at  least,  some  positive  evidence  of  such  centres." 

§  95.  I  have  thought  it  desirable  to  reproduce  with 
some  detail  this  ingenious  hypothesis,  with  Pellati's  com- 
ments thereon,  for  the  reason  that  it  shows  clearly  the 
difficulties  which  recent  observers  have  found  in  accepting 
the  older  theory  of  the  igneous  eruption  of  ophiolites, 
and,  moreover,  brings  clearly  into  view  many  points 
which  are  of  importance  for  the  solution  of  the  problem 
before  us  of  the  true  relations  of  these  ophiolites  to  the 
surrounding  strata.  In  view  of  the  fact  that,  the  resem- 
blance between  the  supposed  eocenic  and  the  eozoic 
ophiolites  is  so  strong  that  the  two  cannot  be  clearly  dis- 
tinguished or  separated  from  one  another,  —  as  we  have 
seen  alike  from  the  comparisons  of  Bonney  and  the 
admissions  of  the  recent  Italian  geologists  themselves 
(§  88),  it  is  not  surprising  that  some  observers,  like  Gas- 
taldi,  should  have  been  led  to  look  upon  thf^  so-called 
eocene  ophiolites  as  nothing  more  than  portions  of  the 
underlying  eozoic  or  pre-paleozoic  series  exposed  through 
geological  accidents.  This  explanation  becomes  more 
plausible  when  we  reflect  that  within  the  great  basin  over 
which  these  ophiolites  are  met  with,  the  paleozoic  and 
mesozoic  rocks  have  but  a  slight  development,  and  are 
often  entirely  wanting,  the  tertiary  rocks  resting  directly 
upon  the  eozoic  pietre  verdi. 

§  96.  My  own  observations  of  the  Italian  ophiolites 
have  been  limited.  I  have  had,  however,  an  opportunity 
of  examining  two  localities  of  these  so-called  eocene  ser- 
pentines, in  eastern  Liguria  and  in  Tuscany.  It  was 
my  good  fortune,  in  October,  1881,  to  spend  a  day  with 
Signer  Capacci  (whose  careful  memoir  on  the  region, 
with  map  and  sections,  I  have  already  noticed),  in  going 


■>•■•:  i't'^'P.^". 


1'1'f 


m<Vi 


h     i 


•190      THE  GEOLOGICAL  HISTORY  OF   SERPENTINES.  iX. 

over  Monteferrato  in  Prato,  near  Florence,  a  locality  for 
centuries  famous  for  its  quarries  of  serpentine,  known  as 
verde-prato.  About  three  miles  from  Prato,  a  town  on 
the  railway  between  Florence  and  Pistoia,  is  the  little 
village  of  Figline,  which  lies  on  the  eastern  slope  of  the 
ophiolitic  mass  in  question,  forming  a  hill  which  rises 
boldly  from  the  plain  of  eocene  limestone  and  shales 
(alberese  and  galestro),  TJie  mass  of  ophiolitic  rockb 
occupies  an  area  somewhat  oval  in  form,  having,  accord- 
ing to  the  determinations  of  Capacci,  a  length  of  about 
2600  metres  from  north  to  south,  and  a  maximum  breadth 
of  about  1800  metres.  In  its  highest  points  it  attains 
elevations  of  400  and  426  metres  above  the  sea,  the  level 
of  the  surrounding  plain  being  about  70  metres.  Figline 
itself,  where  the  serpentine  appears  from  beneath  the 
eocene  strata  lying  to  the  east,  is  at  a  level  of  103  metres, 
but  the  similar  sUuta  on  the  western  side  of  the  hill, 
where  they  apparently  dip  at  high  angles  beneath  the  ser- 
pentine-mass, rise  to  heights  of  295  and  322  metres  above 
the  sea-level. 

§  97.  Underlying  the  alberese,  and  resting  upon  the 
ophiolite  along  :he  eastern  base  of  the  hill,  is  seen  in 
many  places  a  fine-grained,  laminated,  silicious  rock,  gen- 
erally reddish,  but  sometimes  greenish  or  grayish  in  color, 
designated  as  phthanite  by  the  Italian  geologists,  which 
abounds  in  microscopic  forms  referred  by  Bonney  in  part 
to  polycystinae  and  in  part  to  polyzoa.*  This  is  succeeded, 
in  apparent  conformity,  by  the  ordinary  type  of  eocene 
limestones  and  shales,  which,  in  some   places,  however, 

*  Upon  the  organic  forms  found  in  these  and  similar  silicious  or  jas- 
pery  beds,  see  a  memoir  by  Prof.  Dante  Pantanelli  on  the  jaspers  of  Tus- 
cany and  their  fossils  ( I  Diaspri  della  Toscana,  ecc.  Mem.  K.  Acuad.  dei 
Lincei,  ser.  3,  vol.  viii,,  June,  1880  ;  also  Geol.  Mag.  for  the  same  year, 
pp.  317,  504).  These  deposits  are  found  alike  at  various  horizons  in  the 
upper  eocene,  and  in  cretaceous  and  liassic  strata,  often  in  thin  layers 
imbedded  in  argillaceous  sediments.  They  consist  in  part  of  crystalline 
and  in  part  of  amorphous  silica,  with  oxyds  of  iron  and  manganese,  and 
contain  large  numbers  of  radiolarian  forms,  of  many  species,  leading  the 
author  to  conclude  wibii  De  Stefani  that  they  are  deep-sea  deposits. 


i. 


LX. 


X.] 


SEIIPENTINES  OF  ITALY. 


491 


ality  for 
ttowu  as 
bowu  on 
he  little 
)e  of  the 
ich  vises 
id  shales 
tic  rocks 
g,  accord- 
of  about 
n  breadth 
it  attains 
^  the  level 
i.    Figline 
iueath  the 
.03  metres, 
f  the  liill» 
ith  the  ser- 
.trc3  above 

upon  the 
is  seen  in 
rock,  gen- 
ish  in  color, 
dsts,  which 
fiiey  in  part 
succeeded, 
o£  eocene 
>s,  however, 

kilicious  or  jas- 
fjaspers  of  Tus- 
L  11.  Accad.  del 
I  the  same  year, 
Piorlzons  in  the 

1  in  thin  layers 
i-t  of  crystalline 
fmangancse,  and 

pies,  leading  the 
,  deposits. 


rest  directly  upon  the  ophiolite,  or  with  the  intervention 
only  of  a  layer  of  comminuted  serpentine  described  by 
Capacci  as  an  ophiolitic  sand  (arenaria  ojiolUica).  These 
overlying  strata  have  a  general  inclination  from  the  ser- 
pentine, that  is  to  say  to  the  eastward,  of  from  20°  to  70°, 
but  in  some  sections,  as  to  the  east  and  northeast  of 
Figline,  are  represented  in  Capacci's  sections  as  nearly 
horizontal,  with  small  undulations  exposing  in  valleys  the 
phthanite,  and  even  the  serpentine,  beneath  the  alberese. 

§  98.  On  the  western  side  of  the  hill,  where,  as  already 
said,  these  eocene  strata  appear  nearly  up  to  the  summit, 
and  plunge  beneath  the  ophiolite,  their  inclination,  as 
seen  along  the  southwest  border,  is  from  54°  to  64°  to  the 
northeast.  Here  is  observed  a  significant  fact,  which  is- 
shown  in  the  sections  of  Capacci,  —  namely,  that  the  pre- 
viously noted  relations  of  tlie  serpentine,  phthanite,  and 
alberese  are  reversed.  While  on  the  eastern  slope  these 
three  rocks  appear  in  the  ascending  order  just  named,  we 
find  on  the  opposite  flank  of  the  hill,  in  the  ascending 
section,  alberese,  phthanite,  and  serpentine;  —  the  serpen- 
tine overlying  the  phthanite,  and  the  latter  the  alberese. 
The  natural  and  obvious  interpretation  of  these  facts  Is 
that  we  have  here  simply  an  inversion  of  the  natural 
order,  resulting  from  an  overturn  of  the  strata  on  the 
western  side  of  the  hill. 

§  99.  The  ophiolitic  mass  itself  is  not  simple,  but,  as 
described  and  figured  by  Capacci,  is  essentially  composed 
of  two  layers  of  serpentine,  with  an  intercalated  lens  of 
euphotide.  Besides  this  rock,  which  has  been  tlie  object 
of  repeated  studies,  the  last  by  Cossa,  this  lithologist  has 
described  associated  masses  of  diabase,  while  Capacci  has 
observed  others  of  dioritic  rocks,  including  a  green  variety 
distinguished  as  gabbro-verde,  sometimes  becoming  vario- 
litiv.,  as  well  as  the  so-called  gabbro-rosso,  which,  as  there 
seen,  is  an  iron-stained,  somewhat  calcareous  dioritic  rock, 
concretionary  in  structure,  and  apparently  in  a  decom- 
posing state  (§  40). 


492      THE  GEOLOGICAL  HISTORY  OF   SERPENTINES. 


PC. 


§  100.  Capacci's  view  of  the  relations  of  these  various 
rocks  to  one  another,  and  to  the  accompanying  eocene 
strata,  is  in  accordance  with  the  hypothesis  ah-eady  set 
forth  (§  93).  He  legards  the  ophiolite  of  Monteferrato  as 
a  great  lentieuhir  or  almond-shaped  mass  (un' amigdala 
ofiolitica)^  "  intercalated,  in  perfect  concordance  of  stratifi- 
cation, among  the  strata  of  alberese  and  galestro  of  the 
eocene  formation,"  which  have  been  subsequently  tilted, 
so  as  to  give  to  the  whole  series  an  c  stward  inclination. 
In  accordance  with  this  conception,  he  supposes  that,  at  a 
certain  time  during  the  accumulation  of  the  eocene  strata, 
there  came,  from  a  rupture  in  the  earth's  crust,  a  sudden 
effusion  of  an  aqueous  magnesian  magna,  which  was 
spread  out  beneath  the  sea,  and  was  subsequently  overlaid 
by  a  continuation  of  the  eocene  beds,  as  before.  The 
silicious  sediment  constituting  the  phthanite  which,  on 
the  west  side,  is  seen  to  underlie  the  ophiolite  is,  in  this 
view,  a  portion  of  previously  deposited  and  altered  shale, 
while  the  phthanite  on  the  east  side  is  another  portion  of 
a  similar  sediment,  subsequently  laid  down  upon  the 
ophiolite. 

§  101.  The  ophiolitic  mass  is  thus,  like  all  the  other 
serpentines  of  Tuscany,  of  eocene  age.  The  various  rocks 
which  enter  into  its  constitution  appear  in  the  form  of 
"lenticular  masses  or  almond-shaped  concentrations,"  of 
which  the  euphotide  and  the  gabbros  are  examples.  The 
gabbro-rosso  is  found  in  masses  at  the  contact  of  the 
ophiolite  with  the  phthanite,  and  results  from  the  altera- 
tion of  a  diabasic  rock  by  the  action  of  thermal  waters. 
These  have  also  changed  the  galestro  into  the  phthanite, 
found  both  above  and  below  the  ophiolites,  and  in  perfect 
confo'-mity  with  the  adjacent  eocene  strata,  "  which  have 
all  their  distinctive  characters,  and  present  no  traces  of 
alteration  or  of  metamorphism,"  "the  action  which  pro- 
duced the  phthanites  being  local,  particular,  and  variable." 
Recomposed  rocks,  made  up  of  grains  and  fragments  of 
serpentine,  in  a  cement  generally  calcareous,  are  found  on 


SJ 


SERPENTINES  OF  ITALY. 


493 


the  confines  of  the  serpentine  and  at  its  contact  with  tlie 
phthanite.  This  is  especially  seen  at  Poggio,  on  the 
southeast  side  of  the  hill,  wliere  I  found  a  veritable  con- 
glomerate of  fragments  of  serpentine  imbedded  in  a  paste 
of  silicious  slate.  These  facts,  as  well  remarked  by 
Capacci,  show  that  previous  to  the  deposition  of  these 
eocene  beds,  the  serpentine-mass  along  the  shores  v.2  a 
shallow  sea  was  subjected  to  a  process  of  disintegration ; 
"and  that,  moreover,  the  formation  of  a  serpentine 
corresponds  to  a  kind  of  pause  in  the  deposition  of  the 
eocene  strata."  The  ophicalcites,  in  like  manner,  are 
found  at  the  limits  of  the  serpentine,  and  are  breccias  or 
conglomerates  with  a  calcareous  cement. 

§  102.  I  have  thus  given,  in  great  measure  in  language 
translated  from  Capacci's  memoir,  the  principal  facts 
observed  at  Monteferrato,  which  I  have,  for  the  most 
part,  verified.  They,  however,  appear  to  me  incon- 
sistent with  the  hypothesis  propounded  by  the  modern 
school  of  Italian  geologists,  and  with  the  eocene  age  of 
the  ophiolitic  mass  in  question.  The  effusion  of  a  great 
mass  of  aqueous  material  from  the  earth's  interior  into  the 
eocene  sea,  its  subsequent  arrangement  and  crystallization 
into  mountain-masses  of  euphotide,  diorite,  and  serpentine, 
the  elevation  of  these,  and  their  subsequent  disintegration 
to  form  the  ophiolitic  sands  and  conglomerates  already 
described,  riiark  a  geological  period,  and  a  revolution 
which  ought  to  have  left  some  traces  in  the  surrounding 
eocene  deposits.  These,  however,  we  are  to  believe,  in 
accordance  with  the  proposed  hypothesis,  continued  after 
this  event  to  be  laid  down  precisely  as  before, —  the 
alberese  and  the  galestro  previous  and  subsequent  to  the 
ophiolite  making  with  this  one  conformable  series.  This 
process,  moreover,  we  are  told,  was  here  confined  to  an 
area  whose  greatest  extent  was  less  than  three  kilometres, 
and  was  repeated  at  a  great  number  of  localities  in  the 
Italian  tertiary  basin,  in  all  cases  giving  rise,  not,  as  in 
ordinary  eruptions,  to  a  single  kind  of  rock,  but  to  a 


494      THE  GEOLOGICAL  HISTORY  OP  SERPENTINES.  l^. 

group  of  different  rocks,  indistinguishable  in  character 
from  those  which  are  known  to  be  found  in  contiguous 
regions  interstratified  in  crystalline  schists  of  eozoic  age. 

§  103.  The  only  explanation  which  seems  to  me  admis- 
sible, and  one  which  is  in  complete  harmony  with  the 
facts,  is  that  this  area  of  serpentine,  with  its  associated 
euphotides,  etc.,  was  an  eroded  and  uncovered  mass  in 
the  midst  of  the  eocene  sea;  that  around  its  base  was 
deposited  the  disintegrated  material  which  i'^orms  the 
ophiolitic  sands  and  conglomerates,  followed  by  the 
silicious  sediments  which  make  up  the  phthanite,  and  by 
the  limestones  and  shales  of  the  middle  eocene.  The  s\i^- 
sequent  movements  of  the  eartli's  crust,  which  caused  the 
folding  of  these  strata  together  with  the  intruding  mass 
of  eozoic  rock  upon  and  around  which  they  were  depos- 
ited, has  resulted  in  the  production  of  an  overturned 
synclinal  on  the  western  side  of  the  hill. 

§  104.  As  I  have  elsewhere  insisted,*  in  cases  like  the 
present,  where  newer  strata  are  found  in  unconformable 
superposition  to  older  ones,  the  effect  of  lateral  move- 
ments of  compression  involving  the  two  series,  is  fre- 
quently to  cause  the  newer  and  more  yielding  strata, 
along  their  border,  to  dip  towards  or  beneath  the  older 
rock.  These  overlying  strata,  where  they  abut  against 
their  marginal  limit,  which  was  the  ancient  shore-line, 
will,  in  the  conditions  supposed,  assume,  according  to 
local  circumstances,  either  an  anticlinal  or  a  synclinal 
form.  In  the  former  case,  the  inclination  of  the  strata 
towards  the  older  mass,  which  forms  a  resisting  barrier, 
follows  necessarily,  even  though  the  elevation  of  the  arch 
be  slirlit.  In  the  case  of  a  synclinal  fold  or  inverted 
arch,  we  have  the  strata  dipping  away  from  the  older  rock 
at  a  greater  or  less  angle,  as  seen  at  the  eastern  base  of 
Monteferrato,  —  the  strata  appearing  in  their  natural 
order  of  superposition.  When,  as  is  frcviuently  the  case, 
this  inclination  passes  beyond  the  vertical,  giving  I'ise  to 
*  Geological  Magazine  (January,  1882),  ix.,  39. 


X.] 


SERPENTINES  OF  ITALY. 


495 


an  overturned  synclinal,  the  same  strata  will  appear  to 
pass  in  reversed  order  beneath  the  overhanging  mass  of 
older  rock,  as  along  the  svestern  border  of  Monteferrato. 
It  is  hardly  necessary  to  recall  the  fact  that  sharp  or 
inverted  folds,  whether  synclinal  or  anticlinal,  are  often 
attended  with  dislocations  and  vertical  displacements. 
It  may  seem  superlluous  to  insist  upon  these  obvious  prin- 
ciples of  geological  dynamics,  but  I  have  had  occasion  to 
notice  that  they  are  sometimes  overlooked  or  misunder- 
stood even  by  teachers  of  the  science  to-day. 

§  105.  Professor  Bonne3%  who,  as  we  have  seen,  holds 
to  the  igneous  origin  of  ophiolites,  finds  in  the  manner  in 
which  portions  of  the  stratified  silicious  rock  rest  upon 
the  serpentine  near  Figline  what  he  regards  as  a  "  com- 
plete proof"  of  the  eruptive  nature  of  the  serpentine, 
placing  "the  intrusive  character  of  the  latter  beyond  all 
doubt,"  while  he  is  also  satisfied  that  the  great  mass  of 
euphotide  (included  by  him  under  the  name  of  gabbro) 
is  "intrusive  in  the  serpentine."*  Whatever  view  may 
be  held  of  the  origin  of  these  two  rocks  and  their  lela- 
tions  to  one  another,  the  occurrence  of  the  layers  of 
recomposed  ophiolitic  rock  (arenarla  ojioUtlca  and  con- 
glomerato  ofiol'dlco)  interposed,  as  already  described,  be- 
tween the  ophiolitic  mass  and  the  beds  of  phthanite,  and 
even,  as  I  observed  in  one  section  along  the  southeast 
base  of  the  hill,  the  presence  of  fragments  of  serpentine 
in  the  latter,  forces  us  to  the  conclusion  that  these  sedi- 
mentary strata  were  deposited  upon  the  ophiolite,  so  that 
the  theory  of  the  eruption  of  the  latter  since  the  deposi- 
tion of  the  eocene  beds  is  untenable. 

§  106.  The  examinations  which  I  have  been  able  to 
mako  of  the  ophiolitic  rocks  of  Eastern  Liguria,  where  I 
spent  a  little  time  near  Sestri  Levante,  under  the  guid- 
ance of  Prof.  G.  Uzielli  of  Turin,  were  such  as  to  leave  no 
doubt  in  my  mind  that  we  have  here,  as  maintained  by 
Gastaldi,  portions  of  an  ancient  stratified  series  rising  out 
*  Geol.  Magazine,  Au'jtust,  lS7i\  vol.  vl.,  p.  302. 


13 


THE  GEOLOGICAL  HLSTORY  OF  SERPENTINES. 


[X. 


of  the  overlying  eocene.  In  addition  to  the  varieties  of 
serpentine,  and  of  euphotides,  diorites,  diabases  (the  ani- 
phimorphic  rocks  of  Issel  and  Mazzuoli),  we  find  eurites, 
jaspers,  epidutic  and  steatitic  rocks,  with  occasional  lime- 
stoues,  and  various  types  of  argillites,  including  the 
hypophthanites  of  these  authors.  The  whole  series, 
including  its  masses  of  pyrites,  more  or  less  cupriferous 
and  niccoliferous,  presents  a  close  resemblance  to  the 
group  of  strata  accompanying  the  serpentine  of  the  Iluro- 
nian  series  in  Eastern  Canada,  with  which  I  have  long 
been  familiar.  These  rocks  are  well  seen  along  the  valley 
of  the  Acquafredda  —  near  which  I  found,  in  an  eocene 
limestone,  grains  of  the  underlying  serpentine,  as  also 
evidences  of  a  considerable  dislocation  since  the  deposi- 
tion of  the  eocene  strata.  My  observations  at  this  point 
served  to  strengthen  my  conviction  that  the  ophiolite  of 
Monteferrato  is  also  but  a  small  protruding  mass  of  the 
same  series.  I  was  enabled,  subsequently,  as  already 
noticed  (§  54),  to  examine  with  Signor  Quintino  Sella  a 
portion  of  the  ophiolitic  series  of  admitted  eozoic  uge,  as 
seen  in  the  Biellese,  in  the  province  of  Novara,  and  to 
confirm  the  judgments  of  Gastaldi,  Cossa,  Bonney,  and 
others,  as  to  the  apparent  identity  of  these  ancient  ophio- 
lites  with  those  found  in  Eastern  Liguria. 

§  107.  We  have  already  described,  in  §§  22,  23,  the 
mass  of  eozoic  serpentine  which  in  Staten  Island,  New 
York,  rises  from  out  of  the  horizontal  or  gently  inclined 
cretaceous  and  triassic  strata  that  have  been  deposited 
around  its  base.  If  now  we  conceive  this  region  to  be 
subjected  to  such  movements  as  those  which,  along  tlie 
eozoic  belt  a  little  farther  south,  have  compressed  tlio 
Primal  and  Auroral  strata  against  the  northwest  base  of 
the  South  Mountain,  and  given  them  a  southeast  dip,  we 
should  have  a  phenomenon  not  unlike  that  presented  by 
Monteferrato;  that  is  to  say,  a  lenticular  mass  of  ancient 
serpentine  rising  along  the  outcrop  of  southeastward  dip- 
ping mesozoic  rocks,  and  differing  only  by  the  accidental 


s. 


IX. 


•ieties  of 
(the  am- 
[  eurites, 
nal  liiiie- 
cliug   the 
le    series, 
jpriferoua 
je  to   the 
the  Iluro- 
have  long 

the  valley 
an  eocene 
^Q^  as  also 
the  deposi- 
[,  this  point 
Dphiolite  of 
aiass  of  the 

as   already 
tmo  Sella  a 

zoic  uge,  as 
rara,  and  to 
ionney,  and 

cient  ophio- 


\.i 


THE  GENESIS   OF  SERPENTINES. 


497 


circumstame  that  these,  on  the  two  sides,  belong  to  dif- 
ferent mfsoioic  horizons. 

VI.  —  THE  GENESIS   OP   SERPENTINES. 

§  108.  As  regards  the  origin  of  the  serpentine-rocks, 
■\ve  liave  already  noticed  briefly  some  of  the  hypotheses 
which  have  been  proposed.  Although  those  which  sup- 
pose them  derived  by  metasomatic  changes  from  alumi- 
nous or  calcareous  rocks,  either  exotic  or  indigei  ous,  such 
as  granites,  diabases,  granulites,  or  limestones.,  may  be 
considered  as  now  nearly  obsolete,  it  may  not  be  amiss  to 
recall  the  fact  that  they  represent  two  distinct  and  oppo- 
site schools,  which  agree  only  in  admitting  an  unlimited 
alteration  or  change  of  substance  in  previously  formed 
rocks,  through  aqueous  agencies.  The  first  view,  which 
may  be  described  as  a  general  metasomatic  hypothesis 
adapted  to  plutonisra,  m  that  which  derives  not  only  ser- 
pentine but  limestone  from  ordinary  types  of  feldspathio 
rocks,  such  as  granites,  granulites,  gneisses,  diabases,  and 
diorites.  The  integral  conversion  of  all  of  thsse  into 
serpentine  by  the  complete  elimination  of  the  alumina, 
alkalies,  and  lime,  and  the  replacement  of  these  bases  by 
magnesia,  have  be^ii  maintained  by  many  writers  of  repute 
belonging  to  the  school  in  question.* 

§  109.  Others  still  have  supposed  that  the  same  rocks 
might  be  changed  into  limestone,  by  a  complete  removal 
of  the  silica,  also,  and  the  substitution  of  carbonate  of 
lime.  This  extreme  view  has  found  its  boldest  and  most 
consistent  advocates  in  Messrs.  King  and  Rowney,  who 

*  Bonney,  who  maintains  tlie  origin  of  serpentines  by  the  hydration 
of  eruptive  clirysolite  rocks,  has,  in  his  paper  already  cited,  given  many 
reasoi-a  tor  rejecting  the  notion  of  the  formation  of  serpentines  by  meta- 
somatosis  from  the  basic  feldspathic  roclcs  so  often  associated  therewith. 
The  observed  relations  of  the  two  are.  in  his  opinion,  wholly  opposed  to 
this  view,  and  he  insists  upon  the  difficulty  of  conceiving  that  such  a  pro- 
cess of  change  .  hould  be  limited  to  certain  parts  of  a  great  mass,  while 
leaving  adjacent  portions  unaltered.  From  their  distinctness,  he  is  even 
led  to  the  conclusion  that  the  serpentines  and  their  accompanying  eupho- 
tides  and  diorites  belong  to  successive  periods  of  eruption. 


Pz~ 


.'•fWl"  *■     '^'■' 


'     ^■■■1    II  I      mfm^,»mim 


"•,>ML.'^*iiiji'iHtix<i-^imiliM-4- 


i 


>  i 


\   i 


i 

III 

1 

1 

1 

If 

|l 

m 

iiili,:! '. 

498      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X. 

not  only  assert  this  origin  for  the  limestone-masses  found 
in  the  gneisses  of  Sweden  and  tlie  Hebrides,  but  imagine 
that  the  bedded  crystalline  limestones,  many  hundred  feet 
in  thickness,  which  are  interstratified  in  the  Laurentian 
gneissio  series  of  North  America,  and  have  been  traced  in 
continuous  lines  cf  outcrop  for  hundreds  of  miles,  have 
resulted  from  such  an  entire  transformation  of  corre- 
sponding portions  of  the  granitic,  gneissic,  and  pyroxenic 
rocks  of  tlie  series.*  These  very  ingenious  writers  further 
imagine  that  serpentine  also,  —  to  which  they  assign,  in  ac- 
cordance with  tlie  received  views  of  this  school,  an  origin, 
by  metasomatosis  ("or,  as  they  call  it,  methylosis),  from 
dolerite,  melaphyre,  diorite,  euphotide,  and  other  supposed 
plutonic  rocks,  —  is  itself  subject  to  a  similar  change  into 
limestone.  The  existence  of  ophicalcites,  the  presence  of 
masses  of  serpentine,  and  of  such  serpentinic  structures 
as  Uozoon  Canadense,  in  limestone,  are  but  so  many  evi- 
dences to  them  of  a  still  uncompleted  conversion  of  ser- 
pentine into  limestone. 

§  110.  Opposed  to  this  view  of  the  genesis  of  serpen- 
tines and  limestones  by  change  of  substance,  from  plutonic 
rocks,  is  that  which  may  be  described  as  a  general  meta- 
somatic  theory  adapted  to  neptunism,  and  which,  recog- 
nizing the  aqueous  and  sedimentary  origin  of  limestone, 
would  derive  from  it,  by  alteration,  not  only  serpentine, 
but  the  various  other  silicated  rocks  mentioned  above. 
Illustrations  of  this  are  seen  in  the  supposed  conversion 
of  limestone  into  dolomite,  and  of  this  last  into  serpen- 
tine, both  of  which  views  have  found  many  advocates. 
The  probable  change  of  limestone  into  granite  and  into 
gneiss,  was  suggested  by  Bischof,  and  Pumpelly  subse- 
quently, in  1873.  proposed  to  explain  the  genesis  of  the 
bedded  petrosilex-porphyries  or  halleflintas  of  Missouri  by 
the  transmutation  of  a  stratified  limestone,  of  which  por- 

*  See,  for  a  discussion  oi  the  views  of  this  school,  the  author's  Chem. 
and  Geol.  Essays^  pp.  324-325;  also,  An  Old  Chapter  of  the  Geological 
Record,  by  King  and  Rowuey,  1881,  chapters  vii.  and  xii. 


3. 


[X. 


X.] 


THE  GENESIS  OF   SERPENTINES. 


499 


38  found 

imagine 
tired  feet 
lurentian 
traced  in 
iles,  liave 

of  corre- 
pyroxenic 
jrs  further 
sign,  in  ac- 
,  an  origin, 
L>sis),  from 
jr  supposed 
change  into 
presence  of 
I  structures 
)  many  evi- 
L-sion  of  ser- 

s  of  serpen- 
L-om  plutonic 
eneral  meta- 
vhich,  recog- 

,f  limestone, 
serpentine, 
fioned  above, 
id  conversion 
into  serpen- 

ly   advocates, 
jnite  and  into 

npelly  subse- 
snesis  of  the 

jf  Missouri  by 

[of  which  por- 

ae  author's  Chem. 
[of  the  Geological 
11. 


tions  are  found  intcrlaminated  with  the  pctrosilex.*  He, 
at  the  same  time,  suggested  a  similar  origin  for  the  hema- 
titic  iron-ore  which  accompanies  these  porphyries. 

§  111.  With  this  second  hyp(^tlie8is  of  the  origin  of 
serpentines  may  be  mentioned  another,  not,  however, 
involving  mctasomatosis,  which  has  sometimes  been  dis- 
cussed, and  which  was  suggested  by  the  present  writer  in 
1857,  from  tlie  results  of  certain  experiments  on  the  arti- 
ficial formation  of  silicates  of  lime  and  magnesia  by  the 
reaction  between  carbonates  of  thecie  bases  and  free  silica 
in  presence  of  lieated  solutions  of  alkaline  carbonates. 
Such  a  reaction  is  not  without  its  significance,  and,  as  I 
have  elsewhere  shown,  has  doubtless  played  a  part  in  the 
local  development  of  protoxyd-silicates  in  sediments  in 
the  vicinity  of  igneous  rocks  and  of  thermal  alkaline 
waters ;  but  as  an  explanation  of  the  genesis  of  great 
masses  of  comparatively  pure  silicates,  such  as  chrysolite, 
serpentine,  and  steatite,  it  is  obviously  inadequate,  and 
was  abandoned  by  the  writer  in  1860  for  the  view  main- 
tained below.f  Even  if  we  could  suppose  the  presence 
of  sedimentary  beds  containing  the  requisite  elements  in 
proper  proportions,  it  can  be  shown  that  the  reactions 
required  for  the  production  of  silicates  were  inoperative 
in  the  very  regions  where  serpentine  and  steatite  are 
found,  since  side  by  side  with  beds  of  these  there  are  met 
with,  in  many  places,  bed^  of  dolomite  and  of  magnesite 
intimately  mixed  with  quartz,  sufficient  in  amount,  if 
combined,  to  convert  the  accompanying  carbonates  into 
corresponding  silicates. 

§  112.  There  remain,  then,  to  explain  the  origin  of  ser- 
pentine, besides  the  three  hypotheses  just  noticed,  three 
others  already  mentioned,  to  which  we  must  again  refer. 
First  of  these,  we  have  that  which  supposes  the  material 
of  terpentine  to  have  come  from  the  earth's  interior  as  an 

*  Geological  Survey  of  Missouri,  Iron  ores,  etc.,  pp.  25-27;  also  the 
author,  on  Azoic  Rocks,  p.  194,  and  ante,  p.  103. 
t  Chemical  and  Geological  Essays,  pp.  25,  297,  300. 


'  f,i 


il! 


VA    »   •:»    / 


.f»s*iiMaa^..umu:im^.. 


I  "! 


t 


I  !- 


r4 


i 


600     THE  GEOLOGICAL  HlSTOltY  OF  SEUPENTINES.  IX. 

igneous  fused  mass  consisting  essentially  of  chrysolite, 
which  by  8ubse(iuent  liydnition  has  been  changed  into 
serpentine.  Tiiis  str'ctly  plutonic  hypothesis  being,  how- 
ever, by  many  geologists  held  to  be  incompatible  with 
observed  facts  in  the  geognosy  of  serpentine,  one  which 
has  been  called  hydroplutonic,  and  has  already  been  set 
forth  at  length  in  these  pages,  has  found  advocates. 
These,  conceding  that  the  gcognostical  relations  of  ser- 
pentine recjuire  us  to  admit  that  it  was  laid  down  from 
water,  have  conjectured  that  a  material  so  unlike  that  of 
ordinary  aqueous  sediments  was  ejected  from  the  earth's 
interior,  not  in  a  state  of  igneous  lluidity,  but  as  an 
aqueous  magma  or  mud,  consisting  essentially  of  a 
hydrous  silicate  of  magnesia,  which  subsequently  consoli- 
dated into  serpentine,  and  even  into  chrysolite  and  ensta- 
tiiie.  This  view,  as  we  have  seen,  is  maintained  by  a 
sciiool  of  Italian  geologists,  and  Daub'  c,  while  holding 
to  the  origin  of  serpentine  by  the  hydration  of  a  plutonic 
chrysolite-rock,  supposes  this  to  have  passed  into  a  liydrous 
condition  before  its  ejection.* 

§  113.  There  are,  however,  no  facts  in  the  history  of 
vulcanism  to  justify  this  strange  hypothesis  of  an  erupted 
magnesian  mud.  The  materials  known  to  us  as  volcanic 
muds  and  ashes  do  not  differ  essentially,  as  regards  their 
constituent  chemical  elements,  from  other  detrital  matters, 
and  the  origin  of  this  conjecture  may  perhaps  be  traced 
to  the  unfounded  assumption  that  chrysolite  is  peculiarly 
a  plutonic  mineral,  and  that  rocks  in  which  it  and  other 
magnesian  silicates  predominate  are  presumably  plutonic 
in  their  origin.  It  is  at  best  but  a  survival  of  the  belief 
in  a  subterranean  providence,  which  could  send  forth  at 
pleasure  from  its  reservoirs  alike  granite  and  basalt, 
chrysolite-rock  and  limestone,  quartz-rock  and  magnetite. 
A  rational  science,  however,  seeks  in  the  operation  of 
natural  causes  for  the  origin  of  these  various  and  unlike 
mineral  masses,  and  endeavors  to  explain  their  production 
*  Geologic  Experimentale,  p.  542. 


vywolite, 
red  into 
njr,  hoNV- 
b\o  with 
10  which 
been  set 
(.Ivocates. 
,8  of  ser- 
owu  i^om 
le  that  of 
lie  eavth'a 
but   as  an 
[ally   of    a 
tly  consoli- 
aud  eiista- 
ained  by  a 
lile  holding 
i  a  plutonio 
;o  a  hydrous 


Z4 


THE  GENESIS   OF   SERPENTINES. 


601 


in  accordance  with  known  chemical  and  physical  laws. 
Enlightened  geologists  are  now  agreed  as  to  tiie  aqueous 
origin  of  limestones,  of  dolomites,  of  iron-oxyds,  and  o( 
([Uartz,  by  processes  wliieh  are  intelligible  to  every  chem- 
ist, and  the  formation  in  the  humid  way  of  the  native 
silicates  of  magnesia  is  equally  simple  and  intelligible. 

§  114.  It  was,  as  already  set  forth  in  these  pages,  after 
a  careful  study  of  natural  mineral-waters  and  sediments, 
and  of  the  chemistry  of  artificial  magnesian  silieates,  that 
the  present  writer,  in  18G0,  ventured  to  assert  the  aqueous 
origin  of  the  masses  of  native  magnesian  silicates,  and 
their  formation  by  reactions  between  the  soluble  silicates 
of  lime  and  alkalies  from  decaying  rocks  and  the  mag- 
nesian salts  of  natural  waters.*  This  view,  although 
adopted  by  Delesse,  as  we  have  shown  in  §  11,  and  also, 
soon  after,  by  Giimbel,  by  Cre'lMcr,  and  by  Favre,t  has 
not  found  general  recognition.  I  have,  however,  to  record 
the  recent  adhesion  to  it  of  Dieulefait,  ths  eminent  chem- 
ist and  geologist  of  Marseilles,  wdiose  arduous  and  original 
studies  have  already  placed  him  in  the  front  rank  of  stu- 
dents in  terrestrial  chemistry ;  aiul  also  of  Stapff,  the 
learned  and  acute  geologist  of  the  St.  Gothard  tunnel. 

§  115.  The  conclusions  of  Dieulefait,  as  to  the  sedi- 
mentary character  of  the  ser[)entines  of  Corsica,  have 
au'eady  been  mentioned  (§  71).  He  rejects  the  plutonic 
hypothesis  of  the  origin  of  serpentines,  for  the  following 
reasons :  The  frequent  alternation  of  very  thin  beds  of 
serpentine  with  others  of  schists  and  of  limestone  equallj^ 
thin ;  the  changes  in  the  constitution  and  composition  of 
the  serpentinic  layers ;  these,  being  in  one  place  pure  ser- 
pentine, become  gradually  mingled  with  carbonate  of  lime, 
which  at  length  constitutes  a  largf  proportion  of  the  rock, 
and  also  forms  lenticular  masses  .n  the  midst  of  the  calca- 
reous serpentines.  To  all  thes^,  which  are  common  to  the 
serpentines  of  North  America,  we  may  add,  as  noted  else- 

*  Hunt,  Chem.  and  Geol.  Essays,  pp.  122,  296,  317. 
t  Ibid.  pp.  304,  305,  347. 


|l 


502      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  ff. 


,  i 


m'    1 


1  D! 


where,  the  frequent  occurrence  of  grains,  nodules,  layers, 
or  lenticular  masses  of  serpentine  in  beds  of  crystalline 
limestone.  Dieulefait  notes,  moreover,  the  absence  of  any 
signs  of  igneous  action  at  the  contact  between  the  serpen- 
tines and  the  underlying  schists.  He  next  adverts  to  the 
lijdro})lutonic  hypothesis,  and  pertinently  asks  on  what 
gruuiids  we  are  authorized  to  suppose  the  ejection  of  muds 
of  magnesian  silicate  from  the  earth's  interior. 

§  116.  His  own  conclusion  is  that,  while  these  serpen- 
tines are  sedimentary  rocks  in  the  most  complete  accepta- 
tion of  the  term,  the  mud  or  sediment  which  gave  rise  to 
them  was  not  ejected  from  below,  but  was  formed  in  estu- 
aries of  the  sea,  by  reactions  between  the  silicious  matters 
derived  from  the  decay  of  pre-existing  rocks  and  the  mag- 
nesian salts  of  the  sea-water;  in  which  connection  he 
insists  upon  the  frequent  metalliferous  impregnations  of 
the  serpentines,  as  derived  in  like  manner  from  the  older 
rocks.  This  view  of  Dieulefait's,  set  forth  in  1880,*  is,  as 
Lotti  remarks,  no  other  than  "  the  hypothesis  enunciated 
by  Sterry  Hunt,"  twenty  years  earlier.f     Lotti,  for  his 

*  Comptes  Rendus  de  I'Acad.  des  Sciences,  xcl.,  1000. 

[t  This  has  since  been  clearly  stated  by  Dieulefait  himself,  in  a  recent 
elaborate  memoir  on  "  Les  Roches  Ophitiques  des  Pyrenn^es,"  the  result 
of  a  scientific  mission  confided  to  him  in  1880  by  the  Minister  of  Public 
Instruction  in  France  (Ann.  des  Sciences  Geologiques,  1885,  xvi.).  There- 
in, using  the  word  ophite  as  synonymous  with  the  term  ophiolite,  em- 
ployed in  these  pages  to  designate  not  only  serpentine,  but  its  associated 
euphotides,  diabases,  diorites,  etc.,  he  writes:  "The  whole  of  the  reason- 
ing, and  the  facts  already  resumed,  lead  to  the  conclusion  that  the  ophitic 
and  serpentinous  rocks  are  of  sedimentary  origin;  they  have  come  into 
the  condition  in  which  we  now  see  them  entirely  through  the  influ- 
ence of  chemical  reactions  in  the  wet  way,  and  without  ever  having  suf- 
fered the  action  of  heat  from  without.  .  .  .  Following  this  conclusion, 
I  consider  it  my  duty  to  explicitly  formulate  the  following  declaration: 
In  France,  an  honored  veteran  in  geology,  Virlet  d'Aoust,  first  enunciated 
for  the  Pyrennees  the  view  that  the  ophiMc  rocks  are  of  sedimentary  ori- 
gin. This  opinion  was  soon  after  accepted  by  a  geologist  of  great  merit, 
Garrigou,  to  whom  France  has  not  sufficiently  rendered  justice.  But  the 
philosopher  who  first  set  forth  the  question  of  the  sedimentary  origin  of 
the  ophites  in  all  its  bearings,  is  the  illustrious  chemist  and  geologist  of 
Canada,  Sterry  Hunt.    When,  in  a  time  which  I  hope  is  not  far  off,  the 


>       ,1 


ES.  tX. 

3S,  layers, 
rystalline 
ice  of  any 
he  serpen- 
erts  to  the 
3  on  what 
)n  of  muds 

Bse  serpen- 
te  accepta- 
Tave  rise  to 
Lied  in  estu- 
ous  matters 
ad  the  mag- 
Qnection  he 
egnations  of 
)in  the  older 
1880,*  is,  as 
enunciated 

otti,  for  his 

iself ,  in  a  recent 
lees,"  the  result 
nister  of  Public 
5r,,xvi.).   There- 
Ti  opliiolite,  em- 
Lit  its  associated 
,i(>  of  the  reason- 
that  the  ophitic 
have  come  into 
irough  the  influ- 
ever  having  suE- 
this  conclusion, 
dug  declaration: 
;,  first  enunciated 
'sedimentary  orl- 
st  of  great  merit, 
justice.    But  the 
raentary  origin  of 
,  and  geologist  of 
Ls  not  far  off,  the 


X.1 


THE  GENESIS  OF  SEEPENTINES. 


50;] 


part,  while  still  reserving  himself  on  the  question  of  the 
supposed  tertiary  serpentines  of  Italy,  adds,  after  his  own 
studies  of  those  of  Corsica :  "  In  any  case,  it  is  impossible, 
as  Dieulefait  has  said,  to  regard  the  phenomena  offered  by 
these  ancient  serpentines  as  due  to  eruptions,  either  of 
igneous  or  hydroplutonic  magmas.  The  serpentine  has 
either  been  deposited  as  such,  as  maintained  by  Sterry 
Hunt,  and  by  Dieulefait,  o'  is  a  sedimentary  rock  subse- 
quently altered."  *  We  shall  notice  later  on  the  views  of 
Stapff  on  this  subject. 

§  117.  The  masses  of  rock  known  as  serpentine  are  far 
from  homogeneous  in  composition.  Apart  from  the  ad- 
mixtures of  carbonate  of  lime,  dolomite,  and  magnesian 
carbonate,  which  often  enter  into  their  composition,  they 
occasionally  include,  besides  the  hydrated  silicate,  serpen- 
tine, the  anhj'drous  species,  chrysolite  and  enstatite  or 
bronzite,  and  more  rarely  the  hydrous  species,  talc ;  sili- 
cates differing  widely  in  density,  in  chemical  stability,  and 
in  the  oxygen-ratios  between  the  silica  and  the  fixed 
bases  ;  that  for  chrysolite  being  1 : 1,  for  enstatite  2 : 1,  for 
talc,  approximately,  3 : 1,  and  for  serpentine  4 : 3.  These 
differences,  in  the  hypothesis  of  the  aqueous  origin  of  ser- 
pentine, may  well  depend  upon  variations  in  the  composi- 
tion of  the  generating  soluble  silicates,  and  upon  the 
balance  of  affinities  between  silicic  and  carbonic  acids  in 
the  watery  manstruum,  rather  than  upon  the  subsequent 
transformation  of  one  magnesian  silicate  to  another  by 
addition  or  elimination  of  silica  or  magnesia.  The  asso- 
ciation, in  the  same  mass,  of  anhydrous  chrysolite  with  ser- 
pentine is  generally  regarded  as  evidence  of  the  change  of 
chrysolite  into  serpentine ;  but,  while  admitting  the  con- 
conception  of  the  sedimentary  origin  of  the  ophites  sliall  have  definitely 
talcen  its  place  in  science,  the  present  geologists,  and,  above  all,  those  of 
a  future  generation,  will  never  forget  that  the  promoter  and  one  of  the 
most  active  workers  in  this  great  and  fruitful  scientific  revolution  was 
Sterry  Hunt."] 

*  Lotti,  Appunti  Geologici  sulla  Corsica;  Boll.  R.  Comitato  Geologico, 
anno  1883. 


"■fc'  f 


»  i'!i.i^.Sji.;!*«.*rt«.*jjw, 


504      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X. 


h 


version,  under  certain  conditions,  of  both  enstatite  and 
chrysolite  into  hylrous  silicates,  the  view  which  supposes 
the  chrysolite  or  the  enstatite  to  be  simply  an  instance  of 
the  crystallization  of  an  anhydrous  silicate  in  the  midst  of 
an  amorphous  hydrous  silicate,  is  more  consonant  with  the 
hypothesis  of  the  aqueous  origin  of  serpentine-rocks.  It 
is  well  known  that  Scheerer,  from  his  studies  of  the  asso- 
ciated chrysolite  and  serpentine  of  Snarum,  was  led  to 
reject  the  notion  of  the  derivation  of  this  serpentine  from 
a  previously  formed  chrysolite,  and  to  maintain  a  simulta- 
neous formation  of  the  anhydrous  and  the  hydrous  mag- 
nesian  silicates.* 

A  somewhat  analogous  case  is  presented  in  the  occur- 
rence of  grains  of  anhydrous  alumina  or  corundum  found 
in  the  earthy  and  amorphous  aluminous  hydrate,  bauxite, 
which  forms  beds  in  uncrystalline  cenozoic  rocks.f  The 
notion  which  has  been  advanced  that  the  bauxite  has 
come  from  the  hydration  of  previously  formed  beds  of 
corundum,  is  obviously  untenable,  and  we  must  regard 
this  anhydi'ous  alumina  as  formed  by  crystallization  in  the 
midst  of  the  uncrystalline  mass  of  hydrated  alumina. 
De  Senarmont,  in  the  decomposition  of  aqueous  solutions 
of  chlorid  of  aluminium,  at  250"  C,  observed  a  simultane- 
ous production  of  anhydrous  alumina  in  the  form  of 
corundum,  and  of  hydrous  alumina  as  di">spore,  both  crys- 
tallized. J 

§  118.  The  late  studies  of  Arno  Behr  throw  further 
light  on  the  association  of  hydrous  and  anhydrous  spe- 
cies. He  has  found  that  solutions  of  dextrose,  within 
very  narrow  limits  of  temperature  and  concentration, 
yield  crystals  either  of  hydrated  or  anhydrous  dextrose. 


-U 


*  Scheerer.  Pogg.  Annalen,  Ixvlii.,  319,  and  Amer.  Jour.  Science  [2], 
v.,  389,  vl.,  201,  also  xvl.,  217. 

t  Devllle,  An.  de  Ch.  et  de  Phys.  f.S],  Ixi.,  309,  and  IJvnt,  Origin  of 
Some  Magneslan  and  Aluminous  Rocks.  Amer.  Jour.  Scl.,  18G1  [2], 
xxxli.,  281;  also,  Chem.  and  Geol.  Essays,  p.  326. 

t  Comptes  Rendua  de  I'Acad.  des  Sciences,  1856,  xxxU.,  762. 


^<      If 


aci 


THE  GENESIS  OP  SERPENTINES. 


605 


and  that  under  certain  conditions  we  can  obtain  an  ad- 
mixture of  the  two,  as  tlie  result  of  simultaneous  crys- 
tallization.* An  illustration  of  the  influence  of  small 
variations  in  composition  on  the  result  of  a  chemical  pro- 
cess, under  conditions  otherwise  similar,  is  afforded  by  the 
recent  experiments  of  Friedel  and  Sarrasin  on  the  artifi- 
cial production  of  albite  in  the  wet  way.  \\'^hen  a  solution 
of  silicate  of  soda  mixed  with  silicate  of  alumina,  in  the 
proportions  required  to  form  the  soda-feldspar,  was  heated 
in  close  vessels  to  from  400°  to  500°  C,  no  albite  was 
formed,  but  crystals  of  the  hydrated  double  silicate,  anal- 
cite ;  silica,  soda,  and  some  alumina  remaining  in  solution. 
When,  however,  an  excess* of  the  alkaline  silicate  was 
employed,  the  whole  of  the  silicate  of  alumina  was  con- 
verted into  a  crystallized  anhydrous  compound,  which 
was  albite.f 

§  119.  Much  obscurity  still  surrounds  the  question  of 
the  conversion  of  chrysolite  into  serpentine.  In  the  first 
place,  it  is  to  be  remembered  that  the  process  is  one  which 
does  not,  under  ordinaiy  circumstances,  take  place  at  or 
near  the  surface  of  the  earth,  since  chrysolite-roc.:s, 
whether  exotic  masses  or  indigenous  crystalline  schists, 
are  often  met  with,  presenting  no  evidence  of  such  change. 
This  is  Avell  seen  near  Montreal,  where  the  hills  of  chryso- 
litic  dolerite,  demonstrably  of  pre-Silurian  age,  as  well  as 
fragments  of  the  same  rock  imbedded  in  Silurian  con- 
glomerates, alike  contain  only  unaltered  anhydrous  chryso- 
lite. This  mineral,  on  exposed  surfaces,  is  subject  to  a 
sub-aerial  decay,  analogous  to  that  suffered  by  pyroxene 
and  amphibole,  by  which  the  magnesia  and  a  large  propor- 
tion of  the  silica  are  removed,  leaving  a  residue  of  ferric 
oxyd,  as  long  since  observed  by  Ebelmen.  The  change 
of  chrj'solite  into  serpentine  must  then  be  distinct  fi-om 

*  For  these  facts  I  am  indebted  to  a  private  communication  from  Dr. 
Belir.  See  also  his  paper  in  Jour.  Amer.  Chem.  Soc,  in  1882,  vol.  iv., 
p.  11. 

t  Comptes  Rendus  de  1' Acad,  des  Sciences,  July  30,  1883. 


jU 


'■^Hiikmm 


■-'.■^l^^¥!^"/^k^.'mM 


^JaSishJimv^s-s.-if-  ,>w.v:-  ciiasB;' 


506      THE  GEOLOGICAL  HISTORY  OP  SERPENTINES.  tX. 

that  going  on  under  the  influence  of  atmospheric  waters 
near  the  surface. 

§  120.  One  hundred  parts  by  volume  of  chrysolite, 
with  a  spfcjific  gravity  of  3.33,  if  converted  into  a  serpen- 
tine of  specific  gravity  2.50,  without  change  in  its  con- 
tent of  silica,  must  lose  one-eighth  of  its  weight  of 
magnesia,  and  acquire  the  same  amount  of  water  instead, 
while,  at  the  same  time,  its  volume  will  be  augmented  by 
one-third,  or  to  one  hundred  and  tliirty-three  parts.  I 
have  long  since  discussed  this  matter  in  connection  with 
Schecrer's  views  as  to  the  relations  of  these  two  mineral 
species,  noticed  in  §  117.  A  simple  hydration  of  chryso- 
lite would  yield,  not  serpentine,  but  villarsite.  Serpen- 
tine, when  subjected  to  dehydration  and  fusion,  yields,  as 
was  shown  by  the  experiments  of  Daubr<ie,  an  admixture 
of  enstatite  and  chrysolite,  of  which  the  former  should 
contain  one-third  and  the  latter  two-thiids  of  the  fixed 
bases  of  the  serpentine ;  the  oxygen-ratio  of  these  in 
serpentine  being  4 : 3,  while  that  of  chrysolite  is  2:2,  and 
that  of  enstatite,  2:1.  Since,  however,  the  natural 
chrysolite-rock,  as  is  well  known,  often  contains  little  or 
no  enstatite,  it  could  not  have  been  formed  directly  from 
the  simple  dehydration  of  a  silicate  like  serpentine. 

§  121.  In  considering  the  hypothesis  of  the  derivation 
of  serpentine  from  chrysolite-rocks,  such  as  the  so-called 
dunite  and  Iherzolite,  the  question  of  the  geognostical 
relations  of  these  at  once  presents  itself.  The  frequent 
presence  of  ferriferous  chrysolite  in  igneous  rocks,  and 
its  artificial  production  in  the  furnace,  have  given  rise  to 
a  notion  that  it  is  generally  of  igneous  origin,  which  is 
not  justified  by  a  more  extended  inquiry.  It  is  true  that 
eruptive  rocks  sometimes  contain  a  large  proportion  of 
this  mineral,  and  one  of  the  most  remarkable  cases  of  the 
kind  is  that  presented  by  the  granitoid  chrysolitic  dolerite 
long  since  described  by  me,  which  forms  the  hills  of 
Montarville  and  Rougemont,  masses  of  paleozoic  age  in 
the  valley  of  the  Richelieu,  near  Montreal,  which  have 


!IES. 


\X. 


x.i 


THE  GENESIS   OP  SERPENTINES. 


607 


eric  waters 

chi-ysolite, 
0  a  serpen- 
in  its  con- 
,  weigW  of 
iter  instead, 
gmented  by 
•ee  parts.    I 
iiection  with 
two  mineral 
)n  of  chryso- 
lite.    Serpen- 
ion,  yields,  as 
an  admixttire 
[ormer  should 
s  of  the  fixed 
J   of   these   in 
iteis2:2,  and 
.,   the   natural 
itains  little  or 

directly  from  • 
•pentine. 
the  derivation 
IS  the  so-called 
lie  geognostical 
The  fretiuent 
sous  rocks,  and 
e  given  rise  to 
[origin,  which  is 
It  is  true  that 
•e  proportion  of 
'ble  cases  of  the 
.rysolitic  dolerite 
ms  the  hills  of 
paleozoic  age  m 
'•eal,  which  have 


broken  through  the  Utica  sliales  of  the  New  York  system, 
and  converted  them,  near  the  contact,  to  a  flinty  rock. 
An  account  of  this  dolerite,  w^ith  analyses,  has  been  given 
on  pages  211,  212. 

§  122.  The  nearly  pure  magnesian  chrysolite,  which 
has  been  distinguished  by  the  names  of  forsterite  and  bol- 
tonite,  occurs  abundantly  disseminated  in  limestone  in  east- 
ern Massachusetts  (awfe,  page  230),  and  sometimes  forms 
the  greater  part  of  the  mass.  Its  mineralogical  relations 
are  similar  to  the  fluoriferous  magnesian  silicate,  chondro- 
dite,  with  which  it  is  associated  at  Vesuvius,  and  which 
is  also  fou'nl  in  crystalline  limestones  in  eastern  Massa- 
chusetts, as  well  as  in  those  of  the  Laurentian  series  else- 
where, and  is  itself  associated  with  serpentine.  The 
grains  of  both  chondrodite  and  serpentine  are  sometimes 
so  arranged  as  to  mark  ^he  stratification  of  the  limestone ; 
and  in  one  specimen  from  an  unknown  locality,  formerly 
described  by  me,  two  contiguous  layers  in  crystalline 
limestone  contain,  the  one,  chondrodite,  and  the  other, 
serpentine.*  The  analogies  between  the  limestones  hold- 
ing chondrodite  and  serpentine,  and  those  containing  the 
pure  magnesian  chrysolite,  forsterite,  are  very  close,  and 
their  relations  indicate  for  all  of  them  a  common  neptu- 
nian  origin. 

§  123.  We  pass  from  the  chrysolite-bearing  limestones 
to  those  rocks,  composed  chiefly  of  chrysolite,  which  have 
received  tho  names  of  d unite  and  Iherzolite,  and  appear 
to  be  indigenous  interstratified  masses.  Such  was  my 
conclusion  after  examining  them  in  North  Carolina,  in 
strata  referred  by  me  to  the  Montalban  series,  regarding 
which  I  wrote  in  1879:  "Noticeable  among  the  basic 
members  of  the  terrane  is  the  granular  olivine  or  chryso- 
lite-rock which,  often  accompanied  by  enstatite  and  by 
serpentine,  appears  to  be  interstratified  in  the  micaceous 
and  hornblendic  schists  of  the  Montalban  in  North  Caro- 


*  Geology  of  Canada,  p. 
1866,  p.  205. 


4G5.     See  also  the  Geological  Report  for 


11 


-.! 


I     :i 


! 


608      THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X. 

lina  and  in  Georgia."  *  Chrysolite-rocks,  similar  to  those 
of  North  Carolina,  have  been  observed  auiong  the  crystal- 
line schists  in  the  province  of  Quebec,  on  the  south  side 
of  the  Gulf  of  St.  Lawrence,  but  have  not  yet  been  care- 
fully examined. 

§  124.  The  typical  Iherzolite  from  the  Eastern  Pyren- 
nees,  examined  by  Zirkel,  has  since  been  studied  by 
Bonney,  who,  in  1877,t  described  the  rock  and  its  locality. 
It  forms  several  masses  of  considerable  size,  near  Vicdessos 
(Ari^ge),  and  is  in  contact  with  a  saccharoidal  limestone, 
in  which  occur  broad  tongue-like  portions  of  the  Iherzo- 
lite. This  rock  consists  of  chrysolite  with  admixtures  of 
enstatite,  diopside,  and  picotite  (a  chromiferous  spinel), 
the  constituent  minerals  showing  in  their  arrangement  on 
weathered  surfaces  a  "linear  structure"  suggesting  "an 
internal  parallelism,"  which  Bonney,  who  looks  upon  the 
rocks  as  "  igneous,"  regards  as  due  to  movements  of  flow. 
The  rock  varies  from  coarsely  to  finely  granular  in  text- 
ure, and  includes  in  some  cases  a  serpentinic  mineral  in 
its  joints.  The  dunite  of  New  Zealand,  in  specimens 
before  me,  presents,  in  the  arrangement  of  the  contained 
chromite,  a  well  defined  gneissic  structure. 

§  125.  Similar  rocks  are  found  in  Norway,  specimens 
of  which  from  Tafiord,  received  by  the  writer  in  1878  from 
Professor  Kjerulf,  were  micaceous,  and  showed  an  evi- 
dently gneissoid  structure.  These  rocks,  consisting  essen- 
tially of  chrysolite,  holding  enstatite,  diopside,  chromite, 
and  a  grayish  mica,  are  found  interstratified  in  gneiss, 
with  quartzites  and  mica-schists,  sometimes  garnetiferous. 
From  their  late  studies  of  this  rock  in  various  Norwegian 
localities,  Tornebohm,  Reusch,  and  Brogger  agree  that  it 
must  be  classed  among  the  crystalline  schists,  a  judgment 
in  which  Rosenbusch  concurs.  The  reasons  for  this 
conclusion,  as  set  forth  by  Brogger,  are  briefly  as  follows ; 
First,  the  invariably  laminated  structure  of  the  chrysolite- 

*  Macfarlane's  Geological  Hand-Book,  page  13. 
t  Geological  Magazine,  February,  1877. 


US. 


PC. 


•  to  those 
e  crystal- 
outh  side 
)een  care- 

rn  Pyren- 
budied  by 
ts  locality. 
Vicdessos 
limestone, 
Lhe  Iherzo- 
lixtures  of 
us  spinel), 
igement  on 
esting  "an 
s  upon  the 
Ills  of  flow, 
lar  in  text- 
mineral  in 
specimens 
te  contained 


X.] 


STRATIGRAPHY  OF   SEUrENTlNES. 


509 


13. 


rock,  which  is  conformable  to  tliat  of  the  enclosing  gneiss; 
and,  second,  the  variations  in  the  composition  of  the  rock 
itself,  as  seen  in  adjacent  layers.*  With  these  gneissoid 
chrysolite-rucks  of  Norway  may  be  compared  the  chryso- 
lite known  as  glinkite,  found  in  nodules  in  a  talcose 
schist  in  the  Urals,  and  also  the  schists  lately  described 
from  Mount  Ida  in  Greece.f  In  these,  the  transition 
is  seen  from  true  talc-schists  to  talc-schists  containing 
more  or  less  chrysolite,  with  pyroxene,  and  finally  to 
massive  chrysolite-rock ;  the  whole  being  assdfciatetl  with 
other  crystalline  schists  and  with  limestones.  The  ob- 
vious conclusion  from  all  the  above  facts  is  that  no  argu- 
ment in  favor  of  the  igneous  origin  of  serpentine  can  be 
drawn  from  its  supposed  derivation  from  chrysolite-rocks, 
since  these  are  'hemselves,  for  the  greater  part,  of  neptu- 
nian  origin. 

In  this  connection  may  be  noted  the  well  known  fact  of 
the  aqueous  deposition  of  serpentine  in  veins,  in  the  forma 
of  marmolite,  picrolite,  and  chrysotile,  either  alone  or 
with  calcite.  Such  veins,  the  result  of  a  secondary  pro- 
cess, are  often  found  intersecting  ophicalcites  and  serpen- 
tine-rocks at  various  horizons,  and  are  even  met  with  in 
comparatively  recent  serpentine  breccias,  as  noticed  by 
Gastaldi  (§  42). 

VII.  —  STRATIGRAPHICAL   RELATIONS   OF  SERPENTINES. 

§  126.  The  contradictory  opinions  expressed  by  differ- 
ent observers  as  to  the  geognostical  relations  of  serpen- 
tine-rocks in  a  given  area,  —  one  regarding  them  as 
indigenous  and  another  as  exotic  masses,  —  make  it  evi- 
dent that  certain  appearances  are  differently  interpreted, 
according  to  the  theoretical  point  of  view  of  the  observer. 
In  greatly  crushed  and  displaced  strata,  the  varying 
resistance  of  unlike  rocks  undoubtedly  gives  rise  to  acci- 
dents which  are  regarded  by  many  as  evidences  of  poste- 

•  Neues  Jalirbuch  fur  Mineralogie,  1880,  i.,  pp.  187,  195,  197. 
t  Science,  August  31, 1883,  p.  255. 


^4 


m 


s 


m 


mm 


I'll 


,<l    I 


610     THE  GEOLOGICAL  HISTORY  OF  SERPENTINES.  [X, 

rior  intrusions.  The  serpentines  and  related  rocks  of 
Carrick,  in  Ayrshire,  Scotland,  may  be  cited  as  another 
instance  of  this  conflict  of  opinion.  As  described  by 
James  Geikie,  in  1866,*  the  serpentine  and  its  asso- 
ciated greenstones  are  both  indigenous  bedded  rocks, 
interstratified  with  greenish  crystalline  schists,  which  he, 
following  Murchison,  called  altered  Lower  Silurian. 
Geikie,  however,  found  what  he  regarded  as  clear  evidence 
that  these  strata  had  been  greatly  disturbed  while  in  a 
softened  coiUlition.  The  remarkable  resemblance  between 
these  crystalline  schists  of  Carrick  and  those  associateu 
with  the  serpentines  of  Cornwall,  is  noticed  by  Warring- 
ton Smyth.  Bonney,  in  1878,t  rejected  the  conclusions 
of  Geikie,  asserting  that  we  have  in  Carrick,  as  elsewhere, 
truly  eruptive  serpentines,  followed  by  eruptive  gabbros 
of  two  ages,  and,  like  Geikie,  adduced  evidence  in  sup- 
port of  his  own  views. 

§  127.  In  a  critical  notice,  in  1878,  of  Professor  Bon- 
ney's  description  of  the  serpentines  of  Cornwall  and  of 
Ayrshire,  the  present  writer  said :  "  When  it  is  consid- 
ered that  there  is  abundant  evidence  that  the  North 
American  serpentines  are  indigenous,  though  often,  like 
deposits  of  gypsum  and  of  iron-ores,  in  lenticular  masses ; 
and,  further,  that  the  movements  which  the  ancient  strata 
ha\a  suffered,  have  produced  great  crushings  and  dis- 
placements, it  is  not  difficult  to  understand  the  deceptive 
appearance  of  intrusion  which  these  rocks  often  exhibit, 
and  which  are  scarcely  more  remarkable  than  the  acci- 
dents presented  by  coal-seams  in  some  disturbed  and  con- 
torted areas."  |  The  alternately  thickened  and  attenuated 
condition  of  coal-seams  in  such  districts,  and  the  forcing 
of  the  coal  into  rifts  and  openings  in  the  enclosing  sand- 
stone strata,  are  familiar  to  those  who  have  studied  the 
contorted  measures  of  the  Appalachian  coal-field.  The 
latter  phenomenon  especially  is  well  displayed  in  one  of 

*  Geol.  Journal,  xx.,  527.  t  Ibid.,  xxxiv.,  789. 

t  Harpers'  Auuuai  Record,  1878,  p.  293. 


,1     'I 


"'I'll 

v'1 

.1.'!; 


'I'  {! 


ES. 


IX. 


X.] 


STRATIGRAPHY  OF  SERPENTINES. 


611 


rock8  of 
i8  another 
,cribed  by 
I  its  asso- 
led  rocks, 
which  he, 
Silurian, 
ir  evidence 
while  in  a 
ice  between 

associates 
,y  Warring- 
conclusions 
s  elsewhere, 
ive  gabbros 
jnce  in  sup- 

•ofessor  Bon- 
iwall  and  of 
it  is  consid- 
t  the  North 
;h  often,  like 
ular  masses ; 
,ncient  strata 
ngs  and  dis- 
he  dejeptive 
ften  exhibit, 
lan  the  acci- 
bed  and  con- 
id  attenuated 
.  the  forcing 
closing  sand- 
studied  the 
al-field.     The 
ed  in  one  of 

iv.,  789. 


the  elaborate  sections  made  since  1878  by  Mr.  diaries  A. 
Ashburner,  and  published  in  1883  by  the  geological  survey 
of  Pennsylvania,  in  which  the  so-called  Mammoth-vein  is 
shown  as  it  occurs  in  the  Greenwood  basin  of  the  Panther- 
Creek  district.*  The  accidents  in  this  great  forty-foot 
seam  of  anthracite,  there  represented  on  a  scale  of  one 
inch  to  four  hundred  feet,  are  such  as  would,  in  a  rock  of 
conjectured  igneous  origin,  be  deemed  strong  evidence  of 
its  intrusive  character. 

§  128.  We  have  already  referred  to  the  conclusions  of 
Stapff,  with  regard  to  the  indigenous  character  and  sedi- 
mentary origin  of  serpentines.  The  observations  of  this 
eminent  engineer  and  geologist  while  superintending  the 
work  oi  '^e  tunnel  through  Mont  St.  Gothard,  from 
Goschenen  to  Airolo,  in  the  years  1873-1880,  are  set  forth 
at  length  in  his  recent  memoir  accompanying  a  geoSgical 
section,!  which  we  have  noticed  in  §  67.  Lenticu^ir 
masses  of  serpentine  appear  to  the  east  and  west  of  the 
tunnel,  along  the  line  of  which  they  are  intersected  be- 
tween 4870  and  5310  metres  from  the  northern  terminus. 
Having  described  at  length  the  rocks  of  the  section,  he 
adds:  "We  have  in  what  precedes  said  nothing  of  the 
structure  of  the  serpentine,  not  only  because,  from  a  petro- 
graphic  point  of  view,  it  is  to  be  separated  from  the  other 
rocks  of  the  St.  Gothard,  but  also  because  it  evidently  cuts 
these  last,  so  that  it  might  be  considered  as  a  rock  in- 
truded among  them."  Having  stated  in  detail  its  rela- 
tions, he  tells  us  that  "  the  boundaries  of  the  serpentine- 
mass  sometimes  follow  the  stratification  of  the  neigrhborino: 
rocks,  but  sometimes  go  across  it."  Yet,  he  hastens  to 
add,  "  we  nowhere  find  plausible  proof  of  the  penetration 
of  the  serpentine-mass  into  the  encasing  rocks.  This  ser- 
pentine had  originally  the  form  of  a  flattened  lenticular 

*  Second  Geol.  Survey  of  Penn.,  Vol.  I.,  Southern  Coal-Field;  Cross- 
Section  Sheet  ii.,  Section  10. 

t  Profil  g^ologique  du  St.  Gothard  dans  I'axe  du  Grand  Tunnel,  sur 
une  1 :  25,000,  avec  text  explicatif ,  par  Dr.  F.  M.  Stapff,  4to,  pp.  05,  Berne, 
1881. 


j*l>ii2»#2^f**f'' 


612      THE   GEOLOGICAL   HISTORY   OP  SERPENTINES.  [X. 


i;  ■ 


<      ! 


mass,  intercalated  conformably  in  the  stratification  (like 
the  layers  of  eulysite  in  the  gneiss  of  Tunaberg,  in 
Sweden),  and  now  appears,  as  the  result  of  numerous 
breaks  and  displacements,  outcropping  in  a  series  of  little 
lenses,  the  line  joining  which  intersects  at  a  sharp  angle 
the  schistose  lamination  of  the  beds.  Near  to  the  fissures 
which,  with  displacements,  cut  the  mass,  the  rock  adjoin- 
ing the  serpentine  is  stretched  out  and  pushed  back 
(etiree  et  re fo idee'),  both  at  the  surface  and  in  the  interior 
of  the  tunnel." 

§  129.  This  displacement  in  one  case,  on  the  surface, 
was  found  equal  to  450  metres,  and  the  adjacent  strata 
were  bent  in  the  form  of  an  inverted  C.  Tiie  m.ixinmm 
thickness  of  the  serpentine  at  the  outcrop  Avas  100  metres, 
and  the  thickness  of  440  metres,  which  it  attains  in  ^he 
line  of  the  tunnel,  is  believed  by  the  author  to  be  due  to 
the  accumulation,  by  the  movements  described,  of  succes- 
sive portions  of  one  and  the  same  lenticular  mass :  a  con- 
clusion which  is  illustrated  by  a  great  number  of  minute 
observations.  He  adds,  "  The  fissures  along  which  this 
heaping  together  must  have  taken  place,  present  striations 
produced  by  the  sliding  of  the  rock ;  they  are  coated  with 
a  steatitic  matter,  and  sometimes  filled  with  a  friction- 
breccia.  Farther  proofs  of  this  crushing  are  found  in  the 
abrupt  discontinuity  of  the  schistose  and  compact  portions 
of  the  serpentine,  and  in  the  indented  outline  presented 
by  the  upper  surface  of  the  serpentine-mass ;  a  detail  not 
represented  in  the  profile."  The  author  farther  says: 
"  Although  we  would  not  consider  the  serpentine  to  be  an 
intrusive  rock,  we  must  remark  that  it  could  not  have  had 
precisely  the  same  [mechanical]  sedimentary  origin  as  that 
which  we  have  sui)posed  for  the  micaceous  gneiss  which 
encloses  it.  We  may  regard  it  as  originally  a  deposit  of 
hydrated  silicate  of  magnesia,  formed  by  springs,  and  en- 
closed between  the  sediments  which  gave  rise  to  the  mica- 
schists."  The  hydrated  magnesian  silicate  is  supposed  by 
our  author  to  have  been  subsequently  converted  into  an- 


E3. 


IX. 


tion  (like 
uibevg,   ill 
numerous 
es  of  little 
harp  angle 
the  fissures 
:)ck  adjoiu- 
ished  back 
the  interior 

the  surface, 
acent  strata 
le  maxiumm 
1 100  metres, 
,taiiis  in  +he 
to  be  due  to 
;d,  of  succes- 
mass :  a  con- 
)er  of  minute 
ig  which  this 
ient  striations 
e  coated  with 
1  a  friction- 
found  in  the 
ipact  portions 
ine  i)resented 
a  detail  not 
farther  says: 
■ntine  to  be  an 
not  have  had 
7  origin  as  that 
i  gneiss  which 
y  a  deposit  of 
)rings,  and  en- 
,se  to  the  mica- 
is  supposed  by 
erted  into  an- 


S.) 


STUATIGRAl'HY   OF  SERPENTINES. 


613 


hydrous  chrysolite,  etc.,  which  by  a  later  hydration  has 
generated  serpentine,  portions  of  chrysolite  still  remain- 
ing in  the  mass.  It  may  be  questioned  whether  the  phe- 
nomena require  this  hyi)othesis  of  a  double  change  for 
their  explanation.  The  serpentine  contains  imbedded,  in 
some  portions,  not  only  chrysolite,  but  hornblende,  talc, 
and  garnet.  Intercalated  with  the  serpentine,  which  is 
often  distinctly  stratified,  are  layers  of  schistose  talc,  of 
compact  chlorite,  of  actinolite-rock,  of  ferriferous  dolo- 
mite, and  of  mica-schist.  The  serpentine  itself  is  chromif- 
erous,  and  also  contains  magnetite. 

§  130.  Stapff  farther  adds :  "  The  curious  modifica- 
tions of  form  which  the  mass  of  serpentine  has  suffered 
from  the  effect  of  faults,  etc.,  correspond  to  those  of  the 
adjacent  micaceous  gneiss,  but  in  the  case  of  the  former 
they  have  been  better  studied,  for  the  reason  that  it  u 
more  easy  to  define  the  limits  of  these  forms.  If  we  sup- 
pose in  the  section,  in  place  of  the  serpentine,  a  mass  of 
ordinary  micaceous  gneiss  subjei  3d  to  all  the  movements 
of  displacement  and  elevation  which  we  have  here  dis- 
played, we  should  perceive  nothing  more  upon  the  profile 
than  a  uniform  surface  of  micaceous  gneiss,  with  some 
interlacings  of  beds.  It  cannot,  however,  be  denied  that 
movements  arrested  by  the  hard  and  tough  mass  of  the 
serpentine  have  produced  in  the  neighboring  rocks  per- 
turbations much  more  intense  than  would  have  resulted 
from  similar  movements  acting  upon  a  more  tender  rock." 
(Loc.  cit.,  pp.  43-44.)  It  would  be  difficult  to  illustrate 
more  clearly  than  Dr.  Stapff  has  done,  the  manner  in 
which  movements  in  the  earth's  crust  may  affect  inter- 
stratified  masses  of  unequal  hardness  and  tenacity,  giving 
rise  to  accidents  which  simulate  to  a  certain  extent  those 
produced  by  the  intrusion  of  foreign  masses,  and  may 
thus  lead  different  observers,  as  we  have  seen,  to  opposite 
conclusions  with  regard  to  the  geognostical  relations  of 
rocks  like  serpentine  and  euphotide. 


m 


^m 


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J  ,;  ■ 


1^'^  i  I! 

W  I' 


>.    >l 


614      THE  GEOLOGICAL  HISTORY   Or  SERPENTINES.  PC 


CONCLUSIONS. 

The  following  are  the  chief  points  regarding  serpentine 
and  ophiolitic  rocks  which  we  have  sought  to  set  forth  in 
the  preceding  pages  :  — 

1.  To  siiow  historically  the  diversity  of  opinions  as  to 
the  geognostical  relations  of  Kerpentine  and  related  rocks, 
which  have  heen  regarded  by  some  writers  as  eruptive 
and  of  igneous  origin,  and  by  others  as  aqueous  and  sedi- 
mentary. 

2.  To  show  how,  from  the  hypothesis  of  their  eruptive 
origin,  came  tlie  application  of  that  of  metasomatosis, 
and  also  to  set  forth  the  hypothesis  of  the  aqueous  origin 
of  serpentine,  explaining  how  silicates  of  magnesia  may, 
on  chemical  grounds,  be  looked  for  at  any  geological 
horizon. 

3.  To  indicate  the  various  horizons  at  which  serpen- 
tines are  found  in  North  America ;  and  first,  those  of  the 
Laurentian,  of  the  Huronian,  and  of  the  younger  or 
Montalban  gneisses ;  in  which  connection  we  have 
noticed  the  serpentines  of  Chester  County,  Pennsylvania, 
and  those  of  New  Rochelle,  Hoboken,  and  Ma'diattan 
and  Staten  Islands,  all  of  which  are  regarded  as  indige- 
nous stratified  rocks ;  the  apparently  intrusive  character 
of  the  serpentine  of  the  latter  locality  being  explained. 

4.  We  have  further  described  the  occurrence  of  serpen- 
tine among  the  Taconian  rocks  in  Pennsylvania,  and  also 
among  the  gypsiferous  rocks  of  the  Silurian  series  at 
Syracuse,  New  York. 

5.  Having  noticed  some  points  regarding  the  nomen- 
clature of  serpentin.,  and  related  rocks,  and  Bonney's 
account  of  the  serpentines  of  Cornwall,  and  of  parts  of 
Italy,  we  have  considered  the  serpentine-bearing  rocks  of 
the  Alps,  in  which  we  show  four  great  groups,  in  ascend- 
ing order,  which  are  the  older  gneiss,  the  pietre-verdi  or 
greenstone  series,  the  newer  gneisses  and  mica-schistp, 
and  the  still  younger  lustrous  schists,  corresponding  re- 


IE8. 


serpentine 
jet  forth  in 

iuions  as  to 
jlated  rocks, 
as  eruptive 
)U8  and  sedi- 

heir  eruptive 
letasomatosis, 
qneous  origin 
iiag^iesia  may, 
,ny   geological 

which  serpen- 
jt,  those  of  the 
he   younger  or 
-tion    we    have 
rennsylvania, 
and  Manhattan 
irded  as  indige- 
^•usive  character 
ng  explained, 
rence  of  serpen- 
llvania,  and  also 
durian  series  at 


X.) 


CCMCLUSIONS. 


615 


sitectivoly  to  the  Lauroiitian,  Iluronian,  Montalban,  luul 
Tucoiiiiiii  of  North  America;  the  second  aiul  thud  of 
these  being  the  Puhidian  and  the  Grampian  of  iJreat 
Britain.*  Serpentiney,  It  was  shown,  occur  in  the  Alps 
intcrstratified  in  the  second,  third,  and  fourth  of  tliese 
groups,  the  youngest  of  which  includes  the  marbles  of 
C.'arrara. 

6.  The  view  that  this  youngest  group  is  mesozoic, 
is  discussed,  and  the  relations  of  all  these  groups  of 
crystalline  schists  to  the  fossiliferous  rocks  of  the  main- 
land, and  of  those  of  Elba  and  Sardinia,  are  sot  forth, 
showing  their  pre-Cambriau  age ;  while  it  is  maintained 
that  the  ophiolKcs  and  other  crystalline  rocks  which  have 
there  been  referred  to  tl;e  tertiary  are  but  exposed  por- 
tions of  these  pre-Cambriau  rocks. 

7.  The  crystalline  rocks  of  the  Simplon  and  the  St. 
Gothard,  and  those  of  Saxony  and  Bavaria,  are  considered, 
and  are  compared  with  the  younger  gneisses  of  North 
America. 

8.  The  relations  of  the  so-called  tertiary  terpentines  to 
the  surrounding  strata  are  elucidated  by  a  detailed  discus- 
sion of  the  mass  of  Monteferrato,  in  Tuscany,  which  's 
regarded  as  of  pie-Cambrian  or  eozoic  age. 

*  It  re.-  Jus  to  be  seen  whetlier  the  Arvonian  series,  which  is  essen- 
tially composed  of  stratified  Uii'leflinta  or  petrosilex-rocks,  passing  into 
quartziferous  porphy.ies,  and  is  largely  developed  at  the  bas»  he 

Huronian  in  parts  of  North  America,  and  of  Great  Britain,  is  not  repre- 
sented In  the  Alps.  Since  we  have  seen  the  serpentines,  Iherzolites, 
euphotides,  diabases,  and  even  the  marbles  of  the  Alps  and  other  regions, 
removed  from  the  category  of  eruptive  mesozoic  and  cenozoic  masses,  and 
shown  to  be  regularly  interbedded  members  of  pre-Cambrian  stratified 
series,  it  is,  I  think,  a  leglti-.  ate  subject  for  inquiiy  whether  the  quartzi- 
ferous porphyries  which  are  so  largely  developeil  at  Uotzen,  and  elsewhere 
in  the  Alps,  and  have  been  regarded  as  eruptive  rocks  of  Permian  age, 
may  not  prove  to  belong  to  a  stratified  series,  the  equivalent  of  the 
Arvonian,  with  which,  to  judge  from  descriptions,  analyses,  and  speci- 
mens, they  bear  a  close  resemblance.  For  an  account  of  these  rocks  of 
Botzen  by  one  who  regards  them  as  plutonic,  see  Judd  in  the  Geological 
Magazine  for  1876,  vol.  xiii.,  pp.  200-214,  and  for  details  with  regard  to 
the  history  of  the  Arvonian  series,  see  the  author  ia  1880,  American 
Jour.  Science  [3]  (xix.,  pp.  274,  278,  et  seq.);  also  ante,  page  409. 


l<4' 


'%  . 


# 


616      THE  GEOLOGICAL  HISTORY  OF  SEKPENTINE3.  [X. 

9.  TL'3  various  theories  proposed  to  explain  tlie  genesis 
of  serpentines  are  considered,  and  that  of  their  aqueous 
origin  is  adopted. 

10.  The  geognostieal  history  of  chrysolite  is  discussed, 
and  the  essentially  neptunian  origin  of  many  chrysolite- 
rocks  is  mdntained. 

11.  The  contradictory  views  as  to  the  geognostieal  rela- 
tions of  serpentine  are  considered,  and  an  attempt  is  made 
to  show  that  the  appearances  of  intrusion,  upon  which 
some  have  insisted,  are  explained  by  subsequent  move- 
ments of  the  strata  in  which  the  serpentines  are  included. 


>t  til 


XI. 


THE  TACONIC  QUESTION  IN  GEOLOGY. 

In  the  investigation  of  the  age  and  relations  of  the  crystalline  stratified  rocks,  it 
became  necessary  to  consider  a  great  series  of  strata  which  by  Maclure  had  been 
culled  Transition,  but  by  Eaton  were,  for  the  greater  part,  included  in  his  Primitive 
divisions,  tlioiigh  placed  by  him  stratigraphically  between  the  gneisses  and  related 
loclis  on  the  one  hiind,  and  the  paleozoic  rocks  on  the  otlier.  That  at  a  later  period 
this  intermediate  series,  through  the  extension  of  the  doctrine  of  regional  metamor- 
phism,  came  to  be  regarded  as  a  local  alteration  of  the  lower  part  of  the  paleozoic, 
and  that  it  bus  been  a  source  of  much  controversy,  are  facts  well  known  to  all  geolo- 
gists. It  had  been  the  task  of  the  writer  to  attempt  with  some  success  the  unravel- 
ling of  the  famous  Cambrian  and  Silurian  controversy  into  which  the  errors  of 
Murchison  had  introduced  confusion,  and  still  it  now  remained  to  essay  the  heavier 
task  of  solving  the  greater  problem  presented  by  a  vast  series  of  rocks,  not  less  widely 
spread,  which  had  perplexed  the  geologists  of  a  generation  ;  a  problem  closely  con- 
nected, moreover,  with  the  Cambrian  and  Silurian  controversy,  and  involving  still 
wider  discordances  of  opinion,  greater  contradictions,  and  more  important  results 
for  the  science  of  geology.  Partial  and  limited  observations,  partisan  spirit,  a 
neglect  of  geological  literature,  and  false  notions  of  metamorphism,  had  each  con- 
tributed to  obscure  the  question.  A  personal  examination  of  localities  throughout 
tlie  country,  a  critical  study  of  the  literature  of  the  Taconic  controversy,  and  a 
candid  discussion  of  all  the  facts  there  made  known  without  regard  to  the  precon- 
ceived opinions  of  myself,  or  of  others,  were  evidently  necessary  for  the  solution  of 
the  problem.  The  reader  of  the  following  pages  must  judge  to  what  extent  these 
ends  have  been  attained.  This  essay  was  presented  to  the  Uoyal  Society  of  Canada, 
the  first  portion,  to  the  end  of  §  135,  on  the  23d  of  May,  1883,  and  the  remainder  on 
the  21st  of  May,  1884.  These  two  portions  have  been  published  respectively  in  the 
first  and  second  volumes  of  the  Transactions  of  the  Society.  Additional  para- 
graphs regarding  the  Green  Pond  Alountain  range  of  New  Jersey,  the  Taconian  and 
Keweenian  of  Lake  Superior,  and  the  Keweenian  and  Cambrian  of  Texas  and  the 
great  American  b.isin,  have  been  added,  giving  the  results  of  later  studies. 


i 


I  II 

i  ' 


ltl  111  -I 


I.  —  INTEODUCTION. 

§  1.  The  history  of  those  stratified  rocks  which  in 
eastern  North  America  have  been  called  the  Taconic 
series,  is  one  of  many  contradictory  opinions,  and  of 
much  obscurity.  Taken  in  the  larger  sense  in  which  the 
name  was  at  one  time  applied,  this  history  moreover  in- 
cludes, besides  those  rocks  to  which  the  appellation  of 
Taconic  or  Taconian  was  subsequently  restricted,  another 
important  series,  sometimes  called  the  Upper  Taconic, 
which,  under  the  names  of  the  Hudson-River  group  and 

517 


H 

m 

wt 

'm 

w 

\ 

w 

m 

' 

'In 

J 

m 

i 

m 

^1 

m 

'i\ 

!'^ 


M 


■  'mjmmki&iiisi;^! 


518 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XL 


the  Quebec  group,  has  been  the  subject  of  prolonged 
controversy.  It  may  here  be  noted  that  one  of  the  latest 
writers  on  the  subject,  whose  views  will  be  discussed  in 
the  present  essay,  still  maintains  for  this  latter  series  the 
name  of  Taconic*  The  questions  involved  in  this  his- 
tory are  of  fundamental  importance,  and  have  hitherto 
been  involved  in  so  much  misconception  that  it  seems 
desirable  at  the  present  time  to  give  a  concise  view  both 
of  the  fabts  and  of  the  various  theories  which  have  been 
held  with  regard  to  the  whole  of  the  rocks  in  question. 

For  this  purpose  we  must  go  back  to  Amos  Eaton,  to 
whom  rightly  belongs  the  honor  of  having  laid  tlie  foun- 
dations of  the  American  school  of  geology,  so  worthily 
continued  by  his  pupils,  James  Hall,  George  H.  Cook, 
and  the  late  Ebenezer  Emmons.  It  is  now  half  a  century 
since,  in  1832,  appeared  the  second  and  revised  edition 
of  Eaton's  "  Geological  Textbook,"  from  which  we  may 
gather  his  matured  views  as  to  the  geological  succession 
in  northeastern  America.  From  this,  and  from  his  pre- 
vious "  Geological  and  Agricultural  Survey  of  the  Erie 
Canal,"  published  in  1824,  I  have  elsewhere  endeavored 
to  frame  a  connected  statement  of  these  views,t  which  is 
here  brieflv  resumed. 

§  2.  Dividing  the  stratified  rocks  of  northeastern 
America  into  five  great  groups,  —  namely:  I.  Primitive; 
II.  Transition  ;  III.  Lower  Secondary ;  IV.  Upper  Second- 
ary; V.  Tertiary,  —  Eaton  supposed  that  each  of  these 
groups  "com mei»ced  with  carboniferous  slate,  and  termi- 
nated with  calcareous  rocks,  having  a  middle  formation, 
the  centre  of  which  is  quartzose."  This  three-fold  divis- 
ion and  alternation  in  each  great  series,  which  Eaton 
regarded  as  universal,  was,  so  far  as  I  know,  the  first  re- 
cognition of  the  principle,  now  so  generally  understood, 
of  cycles  in  sedimentation. 

§  3.   These  three  divisions  evidently  correspond  to  ar- 

*  Marcou,  Bull.  Soc.  G^ol.  de  France,  1880  ;  (3),  ix.,  p.  18. 
t  Azoic  Kocks,  etc.,  pp.  24r-29. 


0U 

prolonged 

the  latest 
Lscussed  in 

series  the 
LU  this  his- 
ve  hitherto 
it  it  seems 
j  view  both 
L  have  been 

qviestion. 
3s  Eaton,  to 
id  the  foun- 

so  worthily 
ye  H.  Cook, 
alf  a  century 
vised  edition 
hich  we  may 
•al  succession 
from  his  pre- 
Y  of  the  Erie 
•e  endeavored 

ws,t  which  is 

northeastern 
I.  Primitive; 
;pper  Second- 
each  of  these 
lite,  and  termi- 
Idle  formation, 
[iree-fold  divis- 

which  Eaton 
|w,  the  first  re- 
lly  understood, 

[-respond  to  ar- 
}),  ix.,  p.  18. 


XL] 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


519 


gillites,  sandstones,  and  limestones,  but  in  the  application 
of  his  scheme  its  author  allowed  himself  considerable 
liberty  of  interpretation,  and  referred  to  his  first  or  argil- 
laceous division,  not  only  clay-slates,  but  the  great  body 
of  crystalline  schists.  In  this  way,  the  first  division  of  the 
Primitive  series  was  made  to  embrace  both  the  gneisses 
of  the  Adirondacks  and  the  Highlands  of  the  Hudson, 
and  the  unlike  crystalline  rocks  of  New  England ;  includ- 
ing, besides  gneisses,  various  hornblendic,  chloritic,  and 
micaceous  schists,  in  some  of  which  strata  the  occurrence 
of  graphite  was  held  to  justify  the  title  of  "  carbonifer- 
ous," applied  to  these  rocks  as  a  whole.  Following  this 
first  division  of  the  Primitive  series  (I.  1),  Eaton  recog- 
nized in  western  New  England  the  second  or  silicious 
division  (I.  2),  and  the  third  or  calcareous  division  (1.  3), 
represented  respectively  by  the  Granular  Quartz-rock  and 
the  Granular  Lime-rock  or  marble  of  the  Taconic  range. 

§  4.  Succeeding  these,  came  the  rocks  of  his  second  or 
Transition  series.  Of  this,  the  first  or  carboniferous  divis- 
ion was  the  Transition  Argillite  (II.  1)  which  in  many 
localities  directly  overlies  the  Primitive  Lime-rock,  and 
consists  in  part  of  roofing-slates,  with  coarser  and  more 
silicious  layers,  and  in  part  of  soft  unctuous  micaceous 
schists.  To  this  Transition  Argillite  succeeds,  according 
to  Eaton,  the  First  Graywacke  or  Transition  Graywacke, 
representing  the  second  or  silicious  division  of  the  Tran- 
sition series  (II.  2),  and  consisting  of  the  so-called  gray- 
wacke-slate,  with  sandstones  and  conglomerates.  The 
base  of  the  First  Graywacke  was  declared  to  rest  uncon- 
formably  upon  the  Transition  Argillite. 

§  5.  The  geographical  distribution  of  the  First  Gray- 
wacke—  a  very  important  point  in  our  present  inquiry  — 
was  carefully  indicated  by  Eaton.  "  It  is  seen  resting 
on  the  Argillite,  near  Col.  Worthington's  on  the  Little 
Hoosic,  near  the  eastern  limit  of  Rensselaer  County.  On 
ascending  the  western  hill  or  ridge,  the  graywacke-slate, 
rubble,  and  millstone-grit  [elsewhere  indicated  by  Eaton 


^ym 


ii 


ill 


''1 


mm 


mm  li'- 


I 


i&M»^s*.fei^aft^■it'*«j;■A«»8;.i.'s>;<i>■;!.a«>»*•c 


620 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


txi. 


as  making  up  the  First  Graywacke]  are  found  in  succes- 
sion. This  ridge  extends  from  Canada,  through  the  State 
of  Vermont  and  Washington,  Rensselaer  and  Columbia 
Counties  in  New  York."  Elsewhere,  we  are  told  by 
Eaton  that  the  rubble  or  conglomerate  of  this  First  Gray- 
wacke "  forms  the  highest  ridges  between  the  Massachu- 
setts line  and  the  Hudson."  He  also  supposed  that  the 
Shawangunk  Mountain  of  Ulster  and  Orange  Counties, 
on  the  west  side  of  the  Hudson,  now  referred  by  New 
York  geologists  to  the  h  orizon  of  the  Second  rrray wacke, 
"is  a  continuation  of  the  grit  and  rubble  of  the  First 
Graywacke  of  Rensselaer  County."  * 

§  6.  To  the  third  or  calcareous  division  of  the  Transi- 
tion series  (H.  3)  was  referred  by  Eaton,  what  he  called 
the  Sparry  Lime-rock,  found  at  the  summit  'of  the  First 
Graywacke,  to  the  east  of  the  Hudson.  In  the  same  divis- 
ion also  was  included  a  group  of  strata  lying  to  the  west 
of  Lake  Champlain,  which  he  designated  the  Calciferous 
Sand-rock  and  the  Metalliferous  Lime-rock.  In  this  latter 
region,  however,  these  Transition  limestones  were  found 
to  rest  directly  upon  the  lower  division  of  the  Primiui  -e 
series ;  the  whole  of  the  intermediate  divisions  beJig 
absent. 

§  7.  The  Transition  limestones  in  this  western  area 
were,  according  to  Eaton,  directl}  followed  by  the  third 
or  Lower  Secondary  series,  the  first  division  of  which 
( III.  1 )  was  described  as  an  argillite  or  gray wacke-slate, 
and  the  second  (HI.  2)  as  a  sandstone  or  millstone-grit ; 
the  two  together  making  what  he  called  the  Second  Gray- 
wacke ;  t^'eclared  by  him  to  be  indistinguishable  from  the 
First  or  Transition  Graywacke,  except  by  the  fact  that  it 
overlies  the  Transition  limestones.  This  Secondary  Gray- 
wacke is  thus  clearly  indentified  with  the  strata  subse- 
quently called  the  Utica  slate,  the  Pulaski  or  Loraine 
shales,  and  the  Gray  or  Oneida  sandstone.  Succeeding  it, 
were  the  Lower  Secondary  limestones,  including  the  Niag- 

•  Geological  Textbook,  2d  ed.,  pp.  74,  93, 123. 


[XL. 

Q.  bucces- 
the  State 
Columbia 

told  by 
irst  Gray- 
Massachu- 
L  that  the 

Counties, 
\  by  Hew 
rraywacke, 

the  First 

;he  Transi- 
b  he  called 
f  the  First 

same  divis- 
to  the  west 

Calciferous 
;n  this  latter 
I  were  found 
le  Primi  ti  '6 
Lsions  be).<g 

vestern  area 
)y  the  third 
)n  of  which 
y^wacke-slate, 
illstone-grit; 
,ecoiid  Gray- 
ble  from  the 
fact  that  it 
ondary  Gray- 
strata  subse- 
or  Loraine 
succeeding  it, 
ing  the  Niag- 

123. 


XI.] 


GEOLOGICAL  SURVEY  OP  NEW  YORK. 


521 


ara,  and  the  Lower  and  the  Upper  Helderberg  divisions,  of 
later  geologis*  The  Medina,  Clinton,  and  Onondaga 
divisions  were  looked  upon  by  Eaton  as  constituting  sub- 
ordinate intercalated  series.  For  the  understanding  of 
the  problems  before  us,  we  need  not  follow  our  author 
above  the  Second  Graywacke ;  though  it  is  important  to 
remark  that  he  first  showed  that  the  Lower  Secondary 
limestones  underlie  alike  the  bituminous  coal  and  tLe 
anthracite  of  Pennsylvania,  both  of  which  he  placed  in 
the  Upper  Secondary  series ;  thus  correcting  the  error  cl 
Maclure,  who  had  assigned  the  anthracite  to  a  lower 
horizon,  and  placed  it  in  the  Transition  series.  The 
subsequent  study  of  the  Taconl"*  question  will  be  much 
facilitated  by  keeping  in  view  the  classification  and  the 
definitions  of  Eaton,  the  abandonment  of  which  materi- 
ally retarded  the  progress  of  American  geology.  Some  of 
his  once  rejected  views  are  now  universally  accepted, 
and,  in  the  opinion  of  the  present  writer,  a  similar  vindi- 
cation awaits  the  entire  succession  defined  by  Eaton,  so 
far  as  his  Primitive,  Transition,  and  Lower  Secondary 
series  are  concerned.  The  relations  of  these  will  be 
farther  shown  below,  in  a  table  at  the  end  of  the  next 
chapter. 

II.  —  THE  GEOLOGICAL  SURVEY  OP  NEW    YORK. 

§  8.  Such  was  the  state  of  our  knowledge  of  those 
rocks  in  1832.  Five  years  later,  the  geological  survey  of 
New  York  was  begun.  The  Northern  district  of  the 
State  was  then  assigned  to  Ebenezer  Emmons,  a  pupil  of 
Eaton,  and  to  him  we  owe  the  present  nomenclature  of 
what  he  called  the  Champlain  division  of  the  New  York 
system  of  paleozoic  rocks ;  described  by  him  as  resting, 
in  that  egion,  directly  on  the  Primary  series,  and  desig- 
nated as  follows,  in  ascending  order:  1.  Potsdam  sand- 
stone ;  2.  Calciferousi  snnd-r'^ck  (now  known  to  be  a 
dolomite  or  magnesian  limestone)  ;  3.  Chazy  limestone ; 
4.  Trenton  limestone,  with  i  ts  subdivisions^,  the  Birdseye 


Mi&MiMmi). 


M    'H 


•W'     \ 


>l.').\ 


il'  '.  . 


W 


i 


■'*t 


!,f,; 


i! 


522 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


and  Black-River  limestones;  5.  Utica  slate;  6.  Loraine 
shale ;  7.  Gray  sandstone ;  8.  Medina  sandstone.  The 
numbers  7  and  8  were,  as  is  well  known,  subsequently 
separated  from  the  Champlain  division,  and  joined  to 
what  was  called  the  Ontario  division  of  the  New  York 
system. 

§  9.  This  order  was  evident  to  the  west  of  Lake 
Champlain,  where  the  strata  are  nearly  horizontal,  and 
rest  in  undisturbed  succession  on  the  crystalline  rocks  of 
the  Primary  series.  To  the  east  of  the  lake,  however,  and 
thence  southward  along  the  valley  of  the  Hudson,  is 
found  the  belt  of  disturbed  strata,  dipping  generally  to 
the  eastward,  which  had  been  called  by  Eaton,  the  First 
or  Transition  Graywacke,  the  distribution  of  which  has 
been  given  in  §  5.  This  belt,  described  by  Emmons  as 
consisting  of  a  great  thickness  of  green,  red,  and  gray 
sandstones  and  conglomerates,  with  green,  purple,  and 
black  slates,  and  some  associated  limestones,  was  by  him 
now  referred  to  the  horizon  <.f  the  Loraine  shale  and  the 
succeeding  sandstones  (Nos.  6,  7,  and  8),  or,  in  other 
words,  to  the  Second  Graywacke,  lying  above  the  Trenton 
limestone;  which  latter,  according  to  Emmons,  appears, 
in  some  localities,  to  dip  beneath  this  graywacke.  By 
Eaton,  however,  the  strata  of  the  same  belt  had  been 
assigned,  under  the  name  of  the  First  Graywacke,  to  a 
position  below  the  same  Trenton  limestone. 

§  10.  These  views  were  published  by  Emmons  in  1842, 
at  which  time,  as  we  see,  he  dissented  from  the  opinion  of 
Eaton  as  to  the  stratigraphical  horizon  of  the  First  Gray- 
wacke of  the  latter,  and  adopted  that  which  had  been 
put  forth  by  Mather,  to  be  mentioned  below.  As  regards 
the  quartzite  and  limestone  of  the  Primitive  series,  and 
the.  Transition  Argillite,  which,  according  to  Eaton, 
intervene  stratigraphically,  as  well  as  geographically, 
between  the  crystalline  schists  of  the  Primitive  and  the 
First  Graywacke,  Emmons  supposed  that  these  three 
divisions  constitute  a  distinct  group  or  series,  which,  from 


[XI. 

,  Loraine 
le.      The 
sequently 
ioined  to 
^ew  York 

;  of  Lake 
ontal,  and 
e  rocks  of 
iwever,  and 
Hudson,   is 
enerally  to 
1,  the  First 
which  has 
Emmons  as 
i,  and  gray 
purple,  and 
was  by  him 
lale  and  the 
|or,  in  other 
the  Trenton 
)ns,  appears, 
pvacke.    By 
5lt  had  been 
ywacke,  to  a 

mons  in  1842, 
,he  opinion  of 
}  First  Gray- 
ich  had  been 
,     As  regards 
ire  series,  and 
ig   to    Eaton, 
eographically, 
litive  and  the 
;    these   three 
|s,  which,  from 


XI.] 


GEOLOGICAL  SURVEY  OF  NEW  YORK. 


523 


its  development  in  the  Taconic  hills  of  western  "Massa- 
chusetts, lie  named  the  Taconic  system.  This  he  regarded 
as  distinct  from,  and  older  than,  the  New  York  system 
lying  to  the  westward  of  it. 

§  11.  The  survey  of  the  Southern  district  of  New 
York  was  a'^signed  to  Mather,  who,  in  his  final  report  on 
the  region,  in  1843,  described  the  southward  extension  of 
the  various  groups  of  rocks  just  mentioned,  and  main- 
tained, in  opposition  to  both  Eaton  and  Emmons,  that  the 
Taconic  system  of  the  latter  was  a  modification  of  the 
Champlain  division ;  the  quartzite  being  supposed  to 
correspond  to  the  Potsdam,  the  marble  to  the  Calciferous, 
Chazy,  and  Trenton,  and  the  argillite  to  the  Utica  and 
Loraine ;  for  which  latter  subdivision  he  adopted,  as  a 
synonym,  the  name  of  the  Hudson  slates. 

§  12.   As  regards  the  gray  wacke-belt  east  of  the  Hudson 

River,  this  consisted  in  part,  ac Hng  to  Mather,  oi  che 

same  slates  in  a  disturbed  and  altered  condition,  and  in 
part  of  higher  strata,  belonging  to  the  horizon  of  the 
Oneida  and  Medina  subdivisions  of  the  New  York 
system.  He  supposed,  with  Eaton,  that  the  belt  of  these 
rocks,  continued  from  Canada,  through  Vermont,  and 
along  the  east  side  of  the  Hudson,  was  prolonged  south- 
ward, on  the  west  side,  in  the  Shawangunk  range ;  and 
that  the  Green-Pond  Mountain  range,  in  New  Jersey,  was 
also  a  portion  of  the  same  belt,  which  it  lithologically 
resemblco.  Thus,  in  the  view  of  Mather,  the  whole  series 
of  Eaton,  from  the  granular  quartzite  of  the  Primitive  up 
to  the  top  of  the  Second  Graywacke,  was  made  up  of  the 
rocks  of  the  Champlain  division,  with  some  still  higher 
strata.  He  confounded  the  First  with  the  Second  Gray- 
wacke, and  supposed  both  the  clay-slates  of  the  former, 
and  the  underlying  Transition  Argillite  of  Eaton  to  be 
nothing  more  than  local  modifications  of  the  Utica  and 
Loraine  shales.  Lideed,  as  is  well  known,  Mather  went 
80  far  as  to  regard  the  Primitive  crystalline  schists  them- 
selves as  a  farther  modification  of  the  same  Champlain 


j|  fegSBj^*',  '■ 

■K' 

^^^^Bs'^  -i 

Hi! 

^n<i<i^ 

^^^^^H^^  -■IB  ^i- 

^^Kk-''- 

H^^H'^'i 

^^^^^^■'"'-1' 

^^^Bll'^'i 

^^^HMji|#t>  V 

HIHif''il'il 

HkHHm P'r  - ' '': 

^^HmH  S'''i '  11 

^^^^HKi  ^'  ^ 

l^raili 

^^Hlf  1 

H|B||\i 

^^^Hii'tl''  t 

'  ■'!CSS^i»Ta"aE:?r~rmru:  u  *&i. ' 


524 


THE  TACONIC   QUESTION   IN  GEOLOGY. 


PSti 


series.  Emmons,  as  we  have  shown,  while  adhering  to 
the  views  of  Eaton  in  other  respects,  adopted,  at  this 
time,  Mather's  conjecture  as  to  the  horizon  of  the  eastern 
graywacke-belt. 

§  13.  Tlie  name  of  Hudson  slates  had  already,  in  his 
fourth  annual  report  on  the  Southern  district  of  New 
York,  been  given  by  Mather  to  the  strata  which  he  re- 
garded as  equivalent  to  the  Loraine  shale ;  described  by 
Emmons  as  occurring  in  Jefferson  and  Lewis  Counties,  in 
the  Northern  district.  These  strata  were  farther  studied 
by  Vanuxem  in  the  Central  or  intermediate  district,  which 
included  the  counties  of  Oswego,  Oneida,  Herkimer,  and 
Montgomery,  extending  southeastward  along  the  valley  of 
the  Mohawk.  The  rocks  found  in  this  district  were  first 
described  by  Conrad  as  dark  shales  (the  Utica  slates)  suc- 
ceeded by  fossiliferous  lead-colored  shales  alternating  witl 
gray  sandstones,  well  displayed  at  and  near  Pulaski,  in 
Oswego  County.  At  the  summit  of  these  was  a  sand- 
stone quarried  for  grindstones,  and  in  Oneida  County  the 
series  was  overlaid  by  a  quartzose  conglomerate.  These 
were  at  first  called  by  Vanuxem  (who  succeeded  Conrad 
in  the  charge  of  the  survey  of  this  district)  the  Pulaski 
shales  and  sandstones,  and  they  clearly  correspond  to  the 
Loraine  shale  and  the  Gray  sandstone  of  Emmons.  As 
these  shales  were  also  regarded,  both  by  Emmons  and  by 
Vanuxem,  as  identical  with  the  Hudson  slates  of  Mather, 
Vanuxem  included  them  in  what  he  called  the  Hudson- 
River  group ;  a  name  which,  in  subsequent  geological  and 
paleontological  publications,  has  generally  replaced  that  of 
Loraine  shale,  as  being  synonymous  with  it. 

§  14.  The  Hudson-River  group,  however,  according  to 
Vanuxem,  embraced  two  distinct  divisions,  the  upper,  a 
highly  fossiliferous  member  (being  the  Pulaski  shales  and 
sandstone),  found  west  of  the  Adirondacks,  in  Jefferson, 
Lewis,  and  Pulaski  Counties,  and  disappearing  to  the 
southeastward,  in  Oneida  County.  The  lower  member  of 
the  Hudson-River  group,  as  defined  by  Vanuxem,  was 


aC 


an. 

Ihering  to 
d,  at  this 
he  eastern 

3ady,  in  Ws 
ict  of  New 
hich  he  re- 
escribed  by 
Counties,  in 
ther  studied 
strict,  which 
erkinier,  and 
the  valley  of 
■ict  were  first 
ja  slates)  suc- 
ernatingwitl 
ir  Pulaski,  in 
;  was  a  sand- 
da  County  the 
lerate.    These 
leeded  Conrad 
:)  the  Pulaski 
•respond  to  the 
I  Emmons.     As 
Lnmons  and  by 
Les  of  Mather, 
jd  the  Hudson- 
geological  and 
replaced  that  of 

It. 

|er,  accordmg  to 
Is,  the  upper,  a 
llaski  shales  and 
Iks,  in  Jefferson, 
Ippearing  to  the 
[lower  member  ot 
Vanuxem,  was 


XI.] 


G'^OLOGIOAL  SURVEY  OF  NEW  YORK. 


525 


named  tin  I'Vankfort  division,  from  Frankfort,  in  Herki- 
mer Cuuiu^  and  was  described  as  consisting  of  greenish 
argilliies  and  sandstones ;  which  underlie  the  Pulaski  shales 
to  the  northwest,  as  far  as  Jefferson  County,  constitute,  in 
Herkimer  and  Montgomery  Counties,  the  only  representa- 
tive of  the  Hudson-River  gronp,  and  extend  eastward, 
througli  Schenectady,  Albany,  and  Saratoga  Counties,  to 
the  Hudson  River.  This  lower  division  of  tlie  group  was 
said  to  contain  none  of  the  organic  remains  of  the  Pulaski 
or  up])er  division,  but  to  include  some  graptolitic  shales. 
To  this  lower  division,  Vanuxem  supposed,  might  belong 
the  thick  masses  of  contorted  argillaceous  strata,  of  "con- 
troverted age,"  along  the  Hudson  valley. 

He  farther  remarked  that  the  two  divisions  of  the 
Hudson-River  group  "  are  not  co-extensive  with  each 
other.  The  lower  one  enters  from  the  Southern  district, 
along  the  Mohawk,  and  extends  north  by  Rome,  thi'jugh 
Lewis  into  Jefferson  County.  The  upper  division  first 
appears  in  Oneida  County,  and  from  thence,  west  and 
iKjrth,  is  a  co-associate  of  the  Frankfort  slate  or  lower 
division."  These  two  divisions  Vanuxem  insisted  on 
treatij.^  separately,  "inclining  to  the  opinion  that  they 
ought  not  to  be  put  together  in  local  geology."  *  He, 
moreover,  declared  that  the  two  divisions,  although  in 
juxtaposition  in  parts  of  New  York,  occur  separately  in 
Pennsylvania.  The  Pulaski  shales,  having  in  all  respects 
the  same  characters  as  in  New  York,  it  was  said,  are  found 
in  the  Nippenose  valley,  west  of  the  Susquehanna ;  while 
the  Frankfort  slates  and  sandstones  are  seen  to  the  east 
of  the  North  Mountain,  in  the  Kittatinny  or  Appalachian 
valley,  and  include  the  roofing-slates  of  the  Delaware. 

The  Oneida  conglomerate,  which  in  Oneida,  New  York, 
according  to  Vanuxem,  rests  upon  the  Pulaski  shales,  is 
seen  in  Herkimer  County,  overlying  directly  the  Frank- 
fort slates  and  sandstones.  The  same  conditions,  accord- 
ing to  Horton  (Mather's  assistant  in  the  Southern  district 

*  Geology  of  the  Third  district  of  New  York,  pp.  60-67. 


i\ 


■^1^^-:^ 


i.i 


', '. 


I  < 


626 


THE  TACOXIC   QUESTION   IN   GEOLOGY. 


oci. 


of  New  York),  occur  in  Orange  County,  wliere  the  sand- 
stone of  Sliiiwangunk  Mountain  is  said  to  rest  unconform- 
ably  upon  the  edges  of  the  Argilli^e  and  Graywacke 
series. 

§  15.  The  table  on  page  529  will  show  the  relations 
of  the  various  groups  of  stj-ata  already  noticed,  by  a  com- 
parison of  the  divisions  established  by  Eaton  with  those 
adopted  by  the  New  York  geologists,  and  by  others.  It 
should  here  be  repeated  that  Eaton  insisted  upon  the  fact 
that  the  Argillite  is  unconformably  overlaid  by  the  First 
Graywacke.  He  wrote,  "  while  European  geologists  have 
described  a  change  of  direction  at  the  meeting  of  the 
Lower  and  Upper  Secondary,  in  which  the  latter  rests  un- 
conformably upon  the  inclined  edges  of  tho  iormer,  in 
North  America  this  change  takes  place  at  the  meeting  of 
the  Argillite  and  the  First  Graywacke."  He  was  careful 
to  distinguish  between  the  bedding  and  the  slaty  cleavage 
of  the  Argillite,  the  plates  of  which,  he  tells  us,  "  form  a 
large  angle  with  the  general  direction  of  the  rock."  His 
diagrams,  moreover,  show  both  the  non-conformity  of 
stratification  between  the  two,  and  the  independent  slaty 
cleavage  of  the  lower  series.* 

Eaton  did  not  distinguish  the  Potsdam  sandstone  on 
the  west  shore  of  Lake  Champlain  from  what  he  called 
the  Calciferous  Sand-rock,  there  underlynig  the  Metallif- 
erous Lime-rock,  — a  term  (borrowed  from  Bakewell)  by 
which  he  designated  the  Trenton  limestone,  with  its  sub- 
divisions, including  what  he  called  the  Birdseye  or  Encri- 
nal  marble,  and  the  underlying  Chazy.  The  Calciferous 
Sand-rock  he  described  and  figured  as  in  part  marked  by 
geodes  (a  very  distinctive  character),  and  represented  it  as 
the  equivalent  of  the  somewhat  dissimilar  Sparr}^  Lime- 
rock,  found,  to  the  eastward,  at  the  summit  of  the  First 
Graywacke.  Of  this  Sparry  Lime-rock,  he  both  desig- 
nated and  figured  two  varieties,  which  he  called  "  veiny  " 
and  "  tessellated."     The  correctness  of  these  and  of  other 

•  ♦  Geological  Textbook,  pp.  63,  72,  74. 


the  sand- 
inconform- 
Grraywacke 

iie  relations 
I,  by  a  com- 
\vith  those 
-  others.    It 
pou  ibe  fact 
by  the  First 
ologists  have 
etiug  of  the 
tter  rests  un- 
lu;  iormer,  in 
lie  meeting  of 
le  was  careful 
slaty  cleavage 
Is  us,  "  f  o""  ■'^ 
^e  rock."     His 
^conformity  of 
ependent  slaty 


XI.] 


OEOLOaiCAL  SURVEY  OF  NEW  YORK. 


627 


descriptions  by  Eaton,  will  be  acknowledged  by  those 
who  examine  carefully  the  rocks  which  he  described. 

§  10.  In  the  Lower  Secondary  of  Eaton,  what  he 
named  the  Corniferous  or  Cherty  Limo-rock,  with  its  beds 
of  chert  (called  by  him  "stratified  horn-rock"),  is  the 
Upper  Heldcrberg  of  later  geologists,  and  his  Geodiferous 
Lime-rock  is  as  clearly  the  Niagara;  the  Lower  Helder- 
berg  limestone,  and  the  succeeding  Oriskany  sandstone, 
now  regarded  as  the  basal  member  of  the  Devonian,  not 
being  then  recognized.  Besides  the  regular  division  of 
each  group  into  triads  of  argillaceous,  silicious,  and  calca- 
reous rocks,  which  lie  regarded  as  normal,  Eaton  admitted 
the  existence  of  what  he  called  subordinate  or  interposed 
strata.  To  this  class  of  abnormal  rocks,  he  referred,  in 
the  Lower  Secondary,  the  Onondaga  group,  with  its 
marls,  salt,  and  gypsum,  and  also  the  hydraulic  limestone 
or  Water-lime  above  it;  all  of  which  may  be  regarded  as 
interpolated  between  the  Niagara  and  the  Helderberg 
hraestones.  In  the  same  subordinate  class,  also,  were  in- 
cluded by  him  the  red  beds  of  the  Medina  and  the  iron- 
ores  of  the  Clinton. 

§  17.  It  will  be  remembered  that  the  Potsdam  of 
Emmons,  which  (like  the  Calciferous  Sand-rock)  is  often 
wanting  at  the  base  of  the  Champlain  division,  was  un- 
known to  Eaton,  and  hence  does  not  appear  in  our  table, 
from  which  what  he  regarded  as  subordinate  strata  are 
also  omitted.  The  Calciferous  Sand-rock  of  Eaton,  and 
the  underlying  Potsdam  sandstone  were,  by  Emmons,  de- 
clared to  be  represented,  to  the  eastward,  by  the  great 
development  of  strata  included  in  the  Sparry  Lime-rock 
and  the  First  Graywacke,  to  which,  as  a  whole,  he  gave 
the  name  of  Taconic  slates,  and  later  that  of  Upper 
Taconic.  He  farther  declared,  in  1860,  that  the  Primor- 
dial zone  in  Bohemia,  which  includes  Barrande's  first 
fauna,  "  is  in  co-ordination  with  the  upper  series  of  the 
Taconic  rocks."  * 

♦  Emmons,  Manual  of  Geology,  p.  89. 


i   'J 

I  i 

t  .1 


it 


m  'A 


ill  p 

n 


14. 


Il 


i'  Il 

■i       i 


ii'  il 


il 


I  mi 


ii  1- 


'"' 


"p 


p!  I 


t  : 


iLin.ii 


623 


THE  TACONIO  QUESTION  IN  OEOLOOT. 


[XI. 


Tlio  name  of  Ordovician  (sometimes  contracted  to  Or- 
doviun)  which  we  have  introduced  in  this  table,  was  pro- 
posed by  Lapworth,  in  1879,*  to  designate  the  group  of 
paleozoic  rucks  found  in  Wales  between  the  base  of  the 
Lower  Lhind(jvery  and  the  base  of  the  Lower  Arenig. 
Tliese,  conesponding  essentially  to  the  Upper  Cambrii'ii 
or  Bala  groi'p  of  Sedgwick, — the  second  fauna  of  E..r- 
runde,  —  were,  as  is  well  known,  by  a  mistake  in  strati- 
grapliy,  joined  by  Murchison  to  his  Silurian  system,  under 
the  name  of  Lower  Silucian;  and  have  also  since  been 
called  Siluro-Carabrian  and  Cambro-Silurian.  By  making 
of  this  debated  ground  a  separate  region  between  the 
true  Silurian  above  and  the  great  Cambrian  series  below 
(the  Middle  and  Lower  Cambrian  of  Sedgwick),  Lapworth 
has  squght  to  get  rid  of  the  confusion  in  nomenclature, 
and  to  restrain  the  attempts  of  some  to  extend  the  name 
of  Silurian  downwards  even  to  the  base  of  the  Cambrian 
itself.  This  new  division  is  convenient  in  American 
geology  from  the  fact  that  it  includes  the  group  of  strata 
between  the  base  of  the  Silurian  (Oneida)  sandstone  and 
the  base  of  the  Chazj  limestone  ;  the  latter,  together  with 
the  Trenton,  Utica,  and  Loraine  divisions,  being  equiva- 
lent to  the  Ordovician.  The  name  was  given  in  allusion 
to  the  Ordovices,  an  ancient  British  tribe  inhabiting 
North  Wales.  [Hicks,  to  whom  we  owe  so  much  of  our 
knowledge  of  the  paleozoic  rocks  of  Great  Britain,  has 
recently  proposed  to  extend  the  term  Cambrian  above  the 
limits  assigned  by  Sedgwick,  and  to  regard  it  as  including 
three  divisions,  Silurian,  Ordovician,  and  Georgian ;  the 
latter  name,  for  V  e  middle  and  lower  divisions  of  the 
original  Cambrian,  being  derived  from  the  St.  George's 
Channel,  along  which  its  principal  groups  in  Wales  are 
displayed.!] 

The  question  of  the  relations  of  the  great  Keweenian 

*  Geological  Magazine,  vi.,  p.  13. 

+  Geol.  Magazih-  3885,  iil.,  359.  For  a  detailed  account  of  the  f!am- 
brian  and  Silurian  question,  see  Cbem.  and  Geo^  Essays,  pp.  349-386. 


'■  t .'  ^ 


XI.] 


GEOLOGICAL  SURVEY  OF  NEW  YOIIK. 


629 


eat  Keweeman 

;count  of  the  0am- 
,ys,  pp.  a49-386. 


o 

mi 

'A 


H 
W 

5 

Q 

M 

IS 

>> 

h-t 

o 

CO 

O 


o 


o 

CO 


'«k: 


if  !  ■ 


\W    '\\ 


"'-'^-'^ 


?;l 


n^-'ia 


nilki 


i'-fc''avSi3ii^iA4..;ii:i:ftfei>w.wi^^ 


630 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


series  (unknown  to  Eaton),  already  noticed  on  page  415, 
which  lies  at  the  base  of  the  Cambrian,  and  above  the  Ta- 
conian,  will  be  discussed  at  length  farther  on. 

§  18.  We  have  placed  at  the  base  of  the  column,  as 
representing  the  gneisses  and  other  crystalline  rocks 
(Eaton's  Lower  division  of  the  Primitive  series),  the 
names  of  five  groups:  Laurentian,  Norian,  Arvonian, 
Huronian,  and  Montalban,  the  distinctness  of  which,  in 
our  opinion,  is  now  established,  alike  on  stratigraphical 
and  lithological  grounds,  both  in  North  America  and  in 
Europe.  The  following  words,  published  in  1874,  before  the 
recognition  of  the  Arvonian,  are  still  applicable :  "The  dis- 
tribution of  the  crystalline  rocks  of  the  Norian,  Huronian, 
and  Montalban  series  would  seem  to  show  that  these  are 
remaining  portions  of  great  distinct  and  unconformable 
series,  once  widely  spread  out  over  a  more  ancient  floor  of 
granitic  gneiss  of  Laurentian  age ;  but  that  the  four  series 
thus  indicated  include  tlie  whole  of  the  crystalline  stratified 
rocks  of  New  England  is  by  no  means  affirmed.  How 
many  more  such  formations  may  have  been  laid  down 
over  this  region,  and  subsequently  swept  away,  leaving 
no  traces,  or  only  isolated  fragments,  we  may  never 
know;  but  it  is  probable  that  a  careful  study  of  the 
geology  of  New  England  and  the  adjacent  British  prov- 
inces may  establish  the  existence  of  many  more  than  the 
four  series  above  enumerated."  * 


III.  —  GEOLOGICAL  STUDIES   IN    PENNSYLVANIA. 

§  19.  The  reader's  attention  is  now  called  to  the  two 
districts  in  Pennsylvania  mentioned  in  §  14 ;  where  the 
present  writer  has  been  enabled  to  confirm  the  observa- 
tions of  Vanuxem.  To  the  west  of  the  Susquehanna,  in 
Mifflin  County,  is  the  Kishacoquillas  valley,  an  eroded 
anticlinal  valley,  having  a  rim  of  Oneida  sandstone  (the 
Levant,  or  No.  IV.,  of  Rogers),  which  is  the  summit  of 
the   Second   Graywacke  of   Eaton,  and   is   conformably 

*  Huut,  Chemical  and  Geological  Essays,  p.  281. 


[XI. 

11  page  415, 
)Ove  tlie  Ta- 

e  column,  as  . 
alliiie  rocks 
series),  the 
11,  Arvonian, 
,  of  whicli,  in 
tratigrapliical 

n  erica  and  in 
87  4,  before  the 
ble:  "Thed^s- 
ian,  Huronian, 
that  these  are 
unconformable 
ancient  floor  of 
-,  the  four  series 
talline  stratified 
iffirmed.     How 
jeen  laid  down 
t  away,  leaving 
we   may  never 
d  study  of  the 
ant  British  prov- 
j  more  than  the 


1 


,Ued  to  the  two 
^  14 ;  where  the 

tirm  the  observa- 
Susquehanna,  m 

lalley,  an  eroded 
la  sandstone  Cti^e 
is  the  summit  01 
d  is  conformably 


ays,  p 


281. 


XI.] 


GEOLOGICAL  STUDIES  IN  PENNSYLVANIA. 


631 


overlaid,  on  both  of  the  monoclinal  slopes,  by  the  Medina 
and  Clinton  beds.  Passing  downwards  from  the  massive 
sandstones  of  the  rim  to  the  centre  of  the  valley,  we  find 
alternations  of  sandstone  layers  with  sandy  shales,  suc- 
ceeded, in  descending  order,  by  the  Utica  slate  and  the 
Trenton  limestone ;  all  of  which  are  well  characterized, 
both  lithologically  and  paleontologically.  The  whole 
series,  from  the  summit  of  the  sandstone  to  the  base  of 
the  limestone,  here  presents  apparently  one  unbroken 
stratigraphical  succession,  cor"esponding  to  that  already 
described  as  occurring  in  the  central  district  of  New 
York  (§  13),  and  to  what  is  seen  along  the  north  shore  of 
Lake  Ontario,  in  Canada.  A  similar  condition  of  things 
occurs  in  the  Nippenose,  the  Nittany,  and  the  other  so- 
called  coves  or  limestone  valleys,  which  are  found  in 
central  Pennsylvr.xiia,  and,  like  that  of  Kishacoquillas, 
are  eroded  anticlinals.  Accounts  of  these  will  be  found 
in  Rogers'  "Geology  of  Pennsylvania,"  Vol.  I.,  pp. 
460-511;  and  also  in  Report  T.,  on  Blair  County,  by 
Franklin  Piatt,  of  the  Second  geological  survey  of  the 
State.  The  latter  tells  us  that  "  there  is  no  appearance  of 
non-conformability  here  between  III.  and  IV  ";  that  is  to 
say,  between  the  Loraine  shale  and  the  succeeding  Oneida- 
Medina  sandstones.  Within  these  valleys,  there  appears, 
beneath  the  fossiliferous  limestone,  a  great  mass  of  mag- 
nesian  limestones,  several  thousand  feet  in  thickness, 
abounding  in  ores  of  iron  and  of  zinc,  ard  identical  with 
the  limestones  of  the  Appalachian  valley. 

§  20.  When  we  pass  from  the  central  region  of  Penn- 
sylvania to  the  east  of  the  North  or  Kittatinny  Mountain, 
we  find,  along  the  western  border  of  the  Appalachian 
valley,  the  sandstone,  No.  IV.,  which  constitutes  this, 
monoclinal  ridge,  resting  upon  a  great  series  of  schistose 
rocks,  declared  by  Vanuxem  to  belong  to  the  Frankfort 
or  lower  division  of  his  Hudson-River  group,  in  which  he 
included  the  roofing-slates  of  the  region.  The  contact 
between  the  overlying  sandstone  and  these  rocks  is  not, 


m 


^^^H 

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>?4€si4iW4«:4*»#aS*Wi*(«w**>/ 


532 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


I! 


however,  as  in  the  central  valleys,  one  of  conformable 
passage,  through  intercalations,  into  an  underlying  series 
of  fossiliforous  shales,  but,  as  may  be  observed  at  the 
Lehigh  Water-Gap,  one  of  non-conformity.  H.  D.  Rogers 
noted  the  fact  that  the  conglomerates  of  tlie  sandstone. 
No.  IV.,  here  include  "many  rounded  iiebbles  and  frag- 
ments of  the  three  underlying  formations  which  intervene 
between  it  and  the  Primary  rocks  at  the  bottom  of  the 
series."  *  He  recognized  among  the  pebbles  portions  of 
the  Primal  sandstone,  of  chert  derived  from  the  Auroral 
limestone,  and  of  the  Matinal  shites.  The  presence  of 
all  these,  which  I  have  verilied,  is  sufficient  to  show  the 
complete  stratigraphical  break  which  here  separates  this 
Silurian  sandstone  from  the  subjacent  argillites.  These 
latter  are  seen  along  the  banks  of  the  Lehigh,  resting 
in  apparent  conformity  upon  tlie  Auroral  limestone, — 
which,  with  its  overlying  and  interstratified  scliists,  and 
its  subjacent  qui.,  tzite,  makes  up  the  Lower  Taconic  of 
Emmons. 

§  21.  As  the  result  of  my  observations  in  these  two 
regions  of  Pennsylviuiia,  I  stated,  in  1878,  that  the  passage 
in  the  central  valleys  "from  the  Upper  Cambrian  sVales 
into  the  Silurian  sandstones  is  gradual,  and  that  there  is 
no  stratigraphical  break  ;  although,  as  shown  by  Rogers, 
such  an  interruption  occurs  between  these  same  sandstones 
and  the  underlying  slates  along  the  northwest  border 
of  the  great  Appalachian  valley."  f  This  non-conform- 
ity has  been  questioned  by  Professor  Lesley,  but  my  own 
observations  at  the  Lehigh  Water-Gap  are  confirmed  by 
those  published  by  I.  C.  White,  in  1882,  in  his  Report  G. 
6,  of  the  Second  geological  survey  of  Pennsylvania  (pp. 
150,  151),  and  I  repeat  his  statement  that  "the  proof 
seems  conclusive  "  that  the  Silurian  sandstone,  IV.,  here 
rests  unconformably  upon  the  underlying  slates.  Of 
these,  we  have  already  spoken  as  entirely  distinct  from 

*  Second  Annual  Report  on  the  Geology  of  Pennsylvania,  1838,  p.  30. 
t  Chein.  and  Geol.  Essays,  2d  ed.,  preface,  p.  xxi. 


XI.] 


GEOLOGICAL  STUDIES  IN  PENNSYLVANIA. 


533 


niformable 
ying  series 
ved  at  the 
.  D.  Rogers 

sainlstone, 
;s  and  frag- 
jh  intervene 
ittom  of  the 
,  portions  of 
the  Auroral 

presence  of 

to  siiow  the 
separates  this 
Uites.  These 
3high,  resting 

limestone,  — 
sd  schists,  and 
'er  Taconic  of 

t  in  these  two 
hat  the  passage 
anibrian  sVales 
I  tliat  there  is 
wn  by  l^^gers, 
iame  sandstones 
rthwest  border 
is  non-conform- 
jy,  but  my  own 
pe  confirmed  by 
n  his  Report  G. 
jnnsvlvania  (pp- 
Bhat'^'^the  proof 
Istonc,  IV.,  here 
ing   slates.      <Jt 
ly  distinct  from 

.syWania,  1838,  p.  30. 


those  fo&siliferous  shaly  strata  which  underlie  conforma- 
bly the  same  sandstones  in  the  valleys  of  central  Penn- 
sylvania. 

§  22.   By  Prof.  H.  D.  Rogers,  and  his  assistants  on  the 
First  geological  survey  of  Pennsylvania,  the  series  of  rocks 
found  in  the  two  regi(ms  just  mentioned  underlying  the 
sandstone.  No.  IV.,   were    regarded    as   stratigraphically 
equivalent.      He  rightly  identified  the  fossiliferous  sliules 
and  limestones  which,  in  the  central  valleys,  inuuediately 
underlie    this   sandstone,   with   the    Loraine,   Utica,    and 
Trenton  divisions  of  the  Chaniplain  series  of  New  York, 
which  in  his  nomenclature  included  three  great  divisions: 
I.  Primal ;    II.  Auroral ;    III.  Matinal ;    the  first,  or  sili- 
cious,  corresponding  to  the  Potsdam  ;    the  second,  or  cal- 
careous, to  the  Calciferoiis,  Chazy,  and  Tienton;   and  the 
third,  or  argillaceous,  to  the  Utica  and  Loraine.      This 
correlation,    for   the    Trenton,   Utica,  and    Loraine,    was 
established  by  Rogers,  alike  on  stratigraphical  and  paleon- 
tological  grounds,  for  the  central  valleys.      The  rocks  of 
the  great  southeastern  or  Appalachian  valley,  which  were 
seen  to  be  in  many  respects  unlike  the  preceding,  were 
spoken  of  by  Rogers  as  belonging  to  a  distinct  or  "  south- 
eastern type  "  of  the  same  Primal,  Auroral,  and  Matinal 
series.     Herein,  Rogers  adopted  the  view  of  Mather,  who, 
as  we  have  seen  (§  11),  had  already  declared  these  same 
rocks,  in  their    extension    to    the   northeastward,  to   be 
nothing  more  or  less  than  modified  representatives  of  the 
members  of  the  Chami^lain  series.      In  accordance  with 
this  view,  Rogers  called  the  quartzites  and  schists  of  the 
great  valley.  Primal,  the  granular  limestones  or  marbles, 
Auroral,  and  the  overlying  schists  and  argillites,  Matinal. 
Very  great  differences,  both  in  thickness  and  in  lithologi- 
cal  characters,  exist  between  this  series  and  the  Cham- 
plain  division  as  seen  in  northern  New  York  and  central 
Canada;    but  the   rocks  in   question   lie,  in   both  cases, 
between  two  well  defined  geological  horizons,  having  the 
ancient  gneiss  below,  and  the  Oneida,  called  by  Rogers 


[It 


I  ii  ' 


°^*  ,  TV  in  Ws  notation) 

tte  Levant  sandstone  (-«!^  ^sentt^e  same  three-fold 
u    „     and  in  both  cases  they  P""^     i,jaceoas  strata. 
Sn"^"^--;  trTa^ail- thus  suggested,  it 
823.  In  "uPPort  °V    marSngs  to  which  the  name  of 
Js  said  that  the  peo-"*"i  and  which  are  chara^ 

form  touna  i"  tV.p  Potsdam  toim  oi  ^         ^nfl  does 

York  and  Canada.     The  i  o  ^.^^^^^^^^  and  does 

o  T  Ivwe  elsewhere  sm-vv  i.  ifc»    ^.^.^nic  quartzite  ^.u; 

-r^lrtSLtr--"---^^ 

-trXhere  i.  in  ^^^  ^Z:^^'^'^^ 
th!t  te  typical  Potsdam  sand   on    a,  ^,^„„,yi,,„a; 

!^  of  northern  New  York  ex.su  ^^^  ^ 

bat  on  te  contrary  there  -j;  "^^anada,  and  along  the 
that  in  this  region  as  m  eas  eu  _^^^,,  valleys, 

■  lo  nf  the  Champlain  anu  y^jj^ 

;L  upper  Taconic  of  I^^^n  ons  ^^^^^  ,,,,.  .A  to 

farther  on,  is  now  lecogmie  subdivisions.     RocKs 

typical  Potsdam   ^  .fegaywacke-series  are  found 

rnitrallToT^i'v-S-tr^^^^^^  "^ 

Primitive  Quartz^ocV^*-/     „„„.titnte  the  Low..  T» 
Transition  ArgdUte,  -  wi  ^^^^,j  ^^^.^vor  *■    Aow 

■       -^frrreToSlel  Primal,  Auroral,  and   datinal 
reuresentea  uv  v 

o/the  southeastern  area  ^^^^  ^^g^a^^r  with  te 

«  25.   The  Calciforous   »a  ,j„,,,tones    of    -he 

Cha»pla.ndiv.s.o^,^^^^^^^^^^_^^^^^^^^_ 


2. 

is  notation) 
ne  tliree-iolA 
ous  strata, 
suggested,  it 
1  tbe  name  ot 
ch  are  cbarac- 
aike  in  Penn- 
entical  with  a 
Lstone  oi  ^ew 
Scolitlins,liow- 

stinct,  and  does 
nc  qviartzite  ;^^o 
iu  the  Medina 

^   „o  evidence 

me,  1^°        c«     A 
Calciferols  Sand- 

rn  Pennsylvania  •, 
,ons  for  snpposing 
da,  and  along  the 
ison-River  vaUey^ 
of  the  "Ne^v  Yoxlc 
nAzf'  oi  Eaton, 

Iseries  aie  »• 
these,  together  ^      ^ 

them  —namely.  ^« 

l.ime-roch,  and  the 

tute  the  LoNVoi  ia 
\  endeavor  i 

I  T    ond    dAtiniVV 

Unroral,  ano 

togethev  «»h  the 

ly  Rogers  to  be  1  I 
I5-139. 


XI.] 


GEOLOGICAL  STUDIES  IN  PENNSYLVANIA. 


535 


sented,  in  the  area  just  mentioned,  by  the  great  masses  of 
magnesian  limestones  and  marbles,  with  intercalated 
schists,  estimated  by  him  at  from  2500  to  5000  feet  in 
thickness ;  while  the  succeeding  schists  and  argillites 
were  regarded  as  equivalent  to  the  Trenton,  Utica,  and 
Loraine  divisions.  The  large  area  occupied  by  these  rocks 
of  "the  southeastern  type,"  except  in  some  few  locali- 
ties, had  afforded  no  organic  remains  save  the  Scolithus, 
already  mentioned ;  but  the  strata  were  supposed  to  have 
under^  )ne  a  local  alteration,  or  so-called  metamorphism, 
effacing  the  evidences  of  organic  life.  The  limestones  of 
this  series  are  in  fact  more  or  less  crystalline,  and  often 
white  or  banded  granular  marbles.  Moreover,  there  are 
intercalated  both  among  the  limestones  and  the  quartzites 
of  the  series,  peculiar  schists  sometimes  containing  horn- 
blende, serpentine,  talc,  and  chlorite,  besides  damourite, 
pyrophyllite,  and  other  hydrous  micaceoub  species,  which 
liavn  I'oen  mistaken  for  magnesian  silica. t'S,  and  have 
ciuisid  these  rocks,  as  a  whole,  to  be  called  talofiSu  or 
iiiagnesiaii,  Mj;  ly  of  these  silicates,  such  as  ampJiibole, 
serpentine,  and  mica,  aro  alsc  ''ound  in  the  limestones. 

§  2Q.  Tlicse  Taconic  limestones  and  quartz'.Lc?  ;j)ciude, 
more  ive  •.  large  masses  of  iron-ores,  soi^etimes  a  peculiar 
type  •,  ^  magneiite,  more  rarely  of  hematite;  besides  beds 
or  leiibicuh'.v  masses  of  pyrite  and  of  siderite.  The  latter 
two  spc>  ies,  in  regions  where  the  effects  of  sub-aerial  decay 
are  seen  to  'oi^siderable  depths,  are  converted  into  the  so- 
called  brown  hematite  ores  —  limonite  and  turgite  — 
which  are  found  imbedded  in  soft  clayey  and  generally 
iiighly  inclined  strata,  the  results  of  the  decomposition 
and  partial  solution  of  the  limestones  and  their  associated 
schists.  The  limonitic  ores  of  this  horizon  are  extensively 
mined  along  the  outcrop  of  these  Taconic  rocks,  from 
Vermont  +^0  Alabama;  and,  as  lias  been  shown  by  the 
concordant  observations  of  many  investigators,  have  been 
derived  by  eT)igenesis,  in  some  cases  from  the  sulphid, 
and  in  other  cases  from  the  carbonate  of  iron ;  both  of 


[i  1.. 


'' '  :r  ■  I 


m' ' 


4 


?<it[ 


"»      .»;>■  4 


Hi 


-n', 


636 


THE  TACONIC  QUESTION  IN  GEOLOC /. 


[». 


Ul 


which,  in  the  deeper  workings,  are  found  unaltered. 
Crystals  of  magnetite  are  sometiiues  disseminated  through 
these  schists,  as  well  as  thin  layers  of  compact  hema- 
tite, both  of  which  are  occasionally  fcnnd  in  tlie  clayey 
beds  with  the  limonites.  The  massive  granular  magnetic 
ores  of  this  horizon  in  Pennsylvania  are  generally  asso- 
ciated witli  small  quantities  of  pyrite  and  chalcopyrite, 
and  frequently  yield  by  analysis  a  little  cobalt.  They 
are  distinguished  from  the  magnetites  of  the  older  rocks 
by  their  generally  finely  granular  texture  and  feebler 
cohesion,  as  well  as  by  the  characteristic  imbedded 
minerals.  The  hematite  is  often  a  very  soft  unctuous 
micaceous  variety,  and  both  magnetite  and  hematite  are 
occasionally  found  in  grains  disseminated  in  the  soft 
granular  sandstone  layers.  The  limonites  are  often  man- 
ganiferous,  and  are  sometimes  accompanied  by  manganese- 
oxyds,  which  are  doubtless  derived  from  corr*^spo]tding 
manganesian  carbonates.*  Associated  with  the  limestones 
of  this  series  are  sometimes  considerable  interbedded  de- 
posits of  zinc-blende,  and  oxydized  ores  of  zinc  are  found 
at  the  outcrops  of  these. f 

§  27.  As  regards  the  thickness  of  the  strata  which  in 
the  central  region  of  Pennsylvania  underlie  the  sand- 
stone, No.  IV.,  we  find  in  the  Kishacoquillas  and  Nittany 

*  The  few  carbonated  ores  from  this  horizon  in  Pennsylvania,  which 
have  been  analyzed,  are  more  or  less  manganesian  ;  one  of  them  yielding  to 
McCreath  5.0  per  cent  of  manganesian  carbonate.  A  massive  fawn-colored 
carbonate,  with  a  specific  gravity  of  3.25,  found  in  layers  in  the  so-called 
Primordial  slates  of  Placentia  Bay  in  Newfoundland,  gave  me  by  analy- 
sis 81.6  p6r  cent  of  manganesian  carbonate,  and  15.4  per  cent  of  silica 
for  the  most  part  soluble  in  a  dilute  alkaline  solution,  besides  traces  of 
ferrous,  calcareous,  and  magnesian  carbonates.  It  was  partially  incrusted 
with  black  crystalline  manganese-oxyd,  evidently  of  epigenic  origin. 
Amer.  Jour.  Science,  1859,  vol.  xxviii.,  p.  374. 

t  The  chief  facts  in  the  mineralogical  history  of  these  rocks  will  be 
found  in  my  volume  already  cited  ;  Azoic  Rocks,  etc.,  pp.  201,  206.  See 
also  a  description  of  the  Cornwall  Iron-.Mine,  etc.,  Proc.  Araer.  Institute 
Mining  Engineers,  vol.  IV.,  pp.  '.jI[)-o'2'>,  and  two  notes  on  the  Tacouic 
System,  and  on  the  Genesis  of  Iron  Ores,  published  in  the  Canadian 
Naturalist  for  December,  1880  ;  besides  a  farther  discussion  of  this  sub- 
ject, pp.  261-268  of  the  present  volume. 


.  "i 


XI.] 


GEOLOGICAL  STUDIES  IN  PENNSYLVANIA. 


637 


valleys,  respectively  —  for  the  Loraine  shales,  a  thickness 
of  1200  and  700  feet,  for  the  Utica  slate,  400  and  300 
feet,  and  for  the  fossiliferous  Trenton  beds,  400  and  300 
feet.  Beneath  the  latter,  in  these  central  valleys,  lies  a 
great  mass  of  niagnesian  limestones  interstratitied  with 
schistose  beds ;  the  whole  called  by  Rogers,  Auroral,  and 
supposed  by  him  to  be,  like  the  similar  rocks  in  the  east- 
ern part  of  the  State,  the  representatives  of  the  Chazy  and 
Calciferous  divisions  of  the  New  York  system.  To  this 
succession  of  limestones,  as  observed  at  Bellefonte,  Rogers 
assigned  ii  thickness  of  over  5400  feet,  of  which  the  upper 
600  are  highly  fossiliferous ;  while  the  great  underlying 
portion  is  destitute  of  fossils,  or  contJT.>:  jit  few  and  un- 
determined organic  forms.  The  most  complete  section  of 
the  strata  below  the  sandstone.  No.  IV.,  in  the  central 
region,  is  that  lately  measured  by  Mr.  Saunders,  in  Blair 
County  ;  where,  beneath  900  feet  representing  the  Loraine 
and  Utica  shales,  are  found  not  less  than  6600  feet  of 
strata,  inchiding,  at  the  top,  the  fossiliferous  Trenton 
beds,  whose  thickness  is  not  separately  given,  and,  near 
the  base,  intercahited  sandstones  and  shales.*  A  sum- 
mary of  this  section  gives,  in  descending  order :  — 

Feet 
Sandstone,  No.  IV — 

Upper  shales  (Utica  and  Loraine) 900 

Limestones   and    dolomites,   including   tlie  fossiliferous 

Trenton 5400 

White  sandstone 40 

Limestone  with  sandstone  and  shales 1100 

7500 
§  28.  In  none  of  the  sections  of  these  rocks  exposed  in 
the  eroded  anticlinal  valleys  of  the  west,  has  anything 
been  found  corresponding  to  the  older  crystalline  groups 
which,  along  the  border  of  the  southeastern  region,  under- 
lie the  base  of  this  series.  For  the  rest,  these  lower  non- 
fossiliferous  strata  present  similar  mineralogical  characters 

*  Second  geological  survey  of  Pennsylvania,  Report  T,  by  Franklin 
Pratt,  pp.  18,  48-69. 


;:,■!  a-.^jj.fiw.      J_v 


Mfer  tm-^Jm  *•«- 


538 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XL 


to  those  of  the  great  valley  to  the  southeast,  and  include 
extensive  deposits  of  limonite  (imbedded  in  clays,  which 
are  decayed  schists  in  aitu)^  as  well  as  ores  of  zinc ;  both 
of  which  are  largely  mined  in  Blair  County. 

§  29.  If  we  turn  from  these  central  valleys  of  Penn- 
sylvania to  what  Rogers  culled  the  southeastern  area, 
that  is  to  say,  the  regions  lying  to  the  southeast  of  the 
Kittatinny  Mountain,  we  fiuf^  a  very  different  condition 
of  things.  In  place  of  the  9'.  j  feet  of  fossiliferous  shales 
measured  in  Blair  County  between  the  limestone  below  and 
the  overlying  sandstone,  we  find  not  less  than  6000  feet  of 
unfossiliferous  strata.  As  long  since  measured  by  Rogers, 
on  the  west  side  of  tlie  Delaware  River,  at  the  Water-Gap, 
there  are  6102  feet  between  the  base  of  the  sandstone,  No. 
IV.,  and  the  underlying  Auroral  limestone.*  Mr.  Chance, 
in  a  later  section  in  this  vicinity,  makes  them  above  3900 
feet,  and  Lesley  concludes  from  observations  on  the  Sus- 
quehanna that  they  have  an  aggregate  thickness  of  not 
less  than  6000  feet,  which  agrees  with  the  early  measure- 
ments of  Rogers.  The  characters  of  this  great  group  of 
strata  in  tlie  Kittatinny  valley,  included  Loth  by  Rogers 
and  by  the  second  geological  survey  in  the  Matinal  divis- 
ion, are  exceedingly  variable,  and  they  present  important 
local  differences.  The  roofing-slates  already  mentioned 
(§  20)  are  confined  to  a  small  area  in  the  northwest  part 
of  this  valley,  occupying  a  narrow  zone  lying  from  one  to 
three  miles  south  from  the  base  of  the  Kittatinny  Moun- 
tain, and  extending  from  a  point  in  New  Jersey  a  few 
miles  east  of  the  Delaware  Water-Gap,  across  the  Dela- 
ware and  Lehigh,  and  a  few  miles  west  of  the  latter  river. 
These  roofing-slates  were  assigned  by  Rogers  to  the  lower 
part  of  the  group  in  question.  According  to  Chance  also, 
who  has  lately  examined  them,  they  are  very  low  in  the 
series,  and  of  no  great  thickness ;  but  are  affected  by  such 
sharp  flexures  that  the  dips  on  both  sides  of  the  anticlinals 
and  synclinals  are  nearly  parallel,  so  that  the  apparent 

*  Second  Annual  Repci\  1838,  p.  35. 


^d  include 
lys,  which 
zinc;  both 

3  of  Penn- 
tstern  area, 
.east  of  the 
^t  condition 
jrons  shales 
le  below  and 
6000  feet  of 

idbyl^Jge^S' 
5  Water-Gap, 

Indstone,  No. 
Mr.  Chance, 
a  above  8900 
5  on  the  Sus- 
ckness  of  not 
jarly  measure- 
^veat  group  of 
loth  by  Rogers 
:Matinal  divis- 
sent  important 
ady  mentioned 
northwest  part 
ng  from  one  to 
ttatinny  Moun- 
V  Jersey  a  few 
.cross  the  Dela- 
the  latter  river, 
ers  to  the  lower 
r  to  Chance  also, 
very  low  in  the 
affected  by  such 
oftheanticlinals 
Lat  the  apparent 

35. 


XI.] 


GEOLOGICAL  STUDIES  IN  PENNSYLVANIA. 


639 


thickness  of  the  roofing-slates  is  much  augmented.*  In 
the  region  to  the  west  of  the  Lehigh,  in  thu  counties  of 
Berks  and  Lebanon,  these  Matinal  sUites  include  a  great 
amount  of  coarse  arenaceous  rock,  and  rise  into  bold 
hills.  Some  parts  consist  of  heavy  gray  sandstones  with 
conglomerates,  and  bluish  or  grayish  shales  with  thin- 
bedded  limestones.  Large  portions  are  characterized  by  a 
predominant  reddish  or  reddish-brown  color,  with  inter- 
stratified  beds  of  yellow  or  fawn-colored  shales,  and  are 
said  by  Roger;;  to  resemble  the  strata  of  the  Medina  and 
Clinton,  above  No.  IV. 

Mention  should  also  here  be  made  of  the  existence  of 
considerable  masses  of  conglomerate  made  up  of  more  or 
less  completely  worn  pebbles  of  the  Auroral  limestone 
in  a  calcareous  cement,  which  are  found  at  several  points 
in  the  great  valley,  and  have  been  described  by  Rogers  as 
resting  upon  the  Auroral  limestone.f 

§  30.  From  my  observations  in  this  region,  in  1875, 
when  I  had  an  opportunity  of  seeing  the  rocks  of  this 
group  at  several  points  in  the  Appalachian  valley  between 
the  Lehigh  and  Schuylkill  Rivers,  I  was  struck  with  their 
great  resemblance  to  the  First  Graywacke  of  Eaton  (the 
Upper  Taconic  of  Emmons,  or  Quebec  group),  as  seen 
from  the  banks  of  the  St.  Lawrence  at  Quebec,  to  the 
valley  of  the  Hudson ;  which,  it  will  be  remembered, 
was,  by  Mather,  confounded  with  the  Second  Graywacke 
(§  12).  It  is  apparent  from  a  section  to  be  seen  a  little 
west  of  the  Lehigh,  below  Slatington,  that  the  coarse  red 
and  gray  sandstones,  with  red  shales  and  conglomerates, 
overlie  the  roofing-slates  of  the  valley;  and  their  geo- 
graphical relations  are  such  as  to  suggest  an  unconform- 
able superposition. 

§  31.   Regarding  the  rocks  of  this  valley,  I  expressed, ' 
in  1878,  my  belief  "  that  besides  the  Auroral  limestones, 

*  Rogers,  Geology  of  Pennsylvania,  I.,  247  ;  also,  Second  Geol.  Survey 
Penn.,  Report  G  6  ;  pp.  340,  363. 
t  Geology  of  Pennsylvania,  I.,  252. 


m 


I   ) 


h 


I    ' 


T< 


L 


V 


640 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


Pit. 


with  their  succeeding  argillites,  and  the  unconformably 
superimposed  (Oneida)  Silurian  uonglon'.erates  of  tlie 
North  Mountain,  there  are,  to  the  west  of  the  Lehigh 
Uiver,  portions  of  two  intermediate  -.rniations.  One  ol 
these,  marked  by  red-colored  sandstones,  conglomerates, 
and  shites,  appears  to  be  the  same  with  the  Upper  Taconic 
or  Cambrian  belt;  which  has  been  traced  by  II.  D.  Rogers, 
Mather,  Emmons,  Logan  and  the  writer,  with  some  inter- 
rui)tion8,  from  New  Jersey  to  Canada,  aUnig  the  great 
Appalachian  valley.  The  other  is  an  impure  black  earthy 
limestone,  becoming  in  parts  a  soft,  thinly  bedded  flag- 
stone, which  was  seen  lying,  at  moderate  angles,  above 
the  blue  limestone  of  the  valley,  not  far  from  Copley,  and 
was  the  supposed  to  belong  to  a  different  series.  It  is 
apparently  the  same  with  the  Trenton  beds  recognized  by 
Professor  Prime  in  that  vicinity,"  *  as  mentioned  below 
(§34). 

§  32.  We  have  noted  the  evidence  of  a  stratigraphi- 
cal  break  between  the  slates  of  the  great  valley  and  the 
overlying  Levant  (Oneida)  sandstone  in  the  Kittatinny 
Mountain,  and  have  shown  that  the  conglomerates  of  the 
latter  include  numerous  pebbles  derived  alike  from  the 
underlying  Primal,  Auroral,  and  Matinal  rocks.  If  now 
we  turn  to  the  central  valleys  we  find,  as  already  stated, 
no  evidence  of  any  stratigraphical  break  ;  but,  on  the  con- 
trary, a  passage  downwards  from  the  Oneida  sandstone  to 
the  underlying  Loraine  and  Utica  slates.  We  still,  how- 
ever, find  in  these  sandstones  similar  conglomerates  to 
those  of  the  Kittatinny  range.  This  is  well  seen  in  Jack's 
Mountain,  on  the  eastern  border  of  the  Kishacoquillas 
valley,  where  the  Levant  division  is  described  by  Rogers 
as  consisting  in  its  lower  part  of  four  hundred  feet  of  sand- 
stone ;  of  which  he  says,  it  contains  "  numerous  pebbles 
of  white  quartz,  of  Matinal  slate,  and  of  the  harder  Primal 
strata,  and  is  really  a  conglomerate."  The  upper  member 
of  the  Levant,  which  is  still  thicker,  is  also  a  conglomer- 

*  Hunt,  Azoic  Hocks,  p.  215. 


iforinably 
58  of  the 
te  Lehigli 
,    One  ol 
lomerates, 
31-  Tacouic 
D.  Rogers, 
ome  iuter- 
tlie  gveat 
iack  earthy 
ecUled  Hag- 
gles, above 
Oopley,  and 
lies.     It  IS 
cognized  by 
ioned  below 


XI.] 


GEOLOGICAL   STUDIE8   IN   PENNSYLVANIA. 


r)41 


ate,  holding  in  parts  quartz  pebbles,  in  addition  to  which, 
"flat  liuni)8  and  pebbles  of  red  shale  occur  througliout 
the  whole  mass."*  Tiie  jiebbles  of  these  conglomerates, 
which  I  have  examined  in  situ,  have  evidently  nothing  in 
common  with  the  fossiliferous  strata  below  tiiem,  but  are 
derived  from  older  rocks,  like  those  of  the  Kittatinny 
valley,  and  include  large  (juaiitities  of  the  characteristic 
red  shales  which  we  have  already  noticed. 

§  33.  The  thickness  of  the  Auroral  limestones  in  the 
great  valley  is  less  than  farther  west,  being,  according 
to  Chance,  about  3000  feet  ow  the  Sus(iuehanna ;  while 
at  Bethlehem  and  AUentown,  in  Lehigh  County,  they 
measure  about  '2000  feet,  according  to  Prime,  who  thinks 
their  maximum  thickness  there  may  be  2500  feet.  These 
Auroral  limest;nies,  with  their  immediately  associated 
schists  and  limonites,  have  been  carefull}'  studied  by 
Prime  in  the  count}^  just  named,  and  are  described  by 
him  in  Reports  D  and  D  2,  of  the  second  geological 
survey  of  Pennsylvania.  Schistose  layers,  with  limonite, 
are  there  occasionally  intercalated  in  the  limestone,  but 
the  principal  bodies  of  clay,  or  decayed  schist,  holding 
this  ore,  are,  according  to  this  observer,  found  at  two 
horizons,  the  one  near  the  summit  and  the  other  at  the 
base  of  the  limestone,  between  it  and  the  underlying 
quartzite ;  which,  also,  includes  in  this  region,  schistose 
bands  with  hydrous  micas,  limonite,  and  occasional  layers 
of  red  hematite. 

§  34.  These  Auroral  limestones  and  shales  were,  as  we 
have  seen,  supposed  by  Rogers  to  be  the  equivalents  of 
the  New  York  series  from  the  base  of  the  Calciferous 
to  the  summit  of  the  Birdseye  and  Black-R'ver  divisions; 
the  Trenton  limestone  proper  being,  according  to  him, 
represented  in  the  eastern  area  only  by  some  beds  of 
argillaceous  limestone,  uhich  were  by  Rogers  included  in 
the  Matinal  division  of  his  classification.  According  to 
Prime,  "the  Trenton  or  fossiliferous  limestone  seems  to 

•  Rogers,  Geol.  of  Peiin.,  Vol.  I.,  p.  473. 


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23  WBST  MAIN  STREET 

WEBSTER,  N.Y.  14580 

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t/j 


542 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XL 


occur  only  at  a  few  points  in  the  valley,"  having  been 
recognized  by  its  fossils  at  one  locality  only.  It  is  here 
dark-colored,  earthy,  and  uncrystalline,  and  associated 
with  argillaceous  beds  which  yield  a  hydraulic  cement. 
These,  which  are  supposed  to  belong  to  the  same  horizon, 
are  found  at  several  other  places  in  the  region,  overlying 
the  magnesian  limestone.  Prime  also  mentions  one  local- 
ity where  forms  referred  to  Euomphalus  and  Maclurea  are 
met  with,  indicating  the  horizon  of  the  Chazy ;  while  in 
another  an  undesoribed  Lingula  occurs.  Peculiar  funnel- 
shaped  markings,  not  very  unlike  the  Scolithus  of  the 
underlying  quartzites,  have  also  been  found  in  the  magne- 
sian limestoue  in  one  place,  and  have  been  referred  to  the 
genus  Monocraterion,  which  occurs  in  the  Eophyton  sand- 
stone of  Sweden.  For  farther  notice  of  these  organic 
form3  see  the  author's  volume  on  "  Azoic  Rocks,"  p.  206, 
and  also  Professor  Prime's  Report  D  2. 

§  35.  The  Primal  division  of  the  series  under  con- 
sideration is,  in  the  northeast  part  of  the  great  valley, 
in  Pennsylvania  (where  it  rests  unconformably  upon  the 
Laurentian  gneiss),  a  thin  and  irregular  deposit,  and,  ac- 
cording to  Rogers,  is  sometimes  wanting ;  in  which  case 
the  Auroral  limestone  reposes  directly  upon  the  gneiss,  as 
may  be  seen  in  Lehigh  and  Northampton  Counties.  In 
the  North- Valley  Hill,  in  Chester  County,  and  farther  to 
the  northeast,  in  Lehigh  County,  the  Primal  quartzite, 
often  with  Scolithus,  is  seen  to  rest,  with  a  thickness  of 
from  twenty  to  fifty  feet,  directly  upon  the  Laurentian 
gneiss.  These  basal  beds  in  Chester  County  include  some 
micaceous  and  schistose  layers,  and  are  followed  by  the 
Upper  Primal  slates  and  the  Auroral  limestones.  The 
rock  is  sometimes  granular,  and  often  detrital,  while  at 
other  times  it  is  a  hard  granular  or  even  flinty  quartzite. 
Farther  to  the  soutliwest,  in  Berks  County,  the  Primal 
quartzite  becomes  more  continuous  and  thicker,  rising  in- 
to high  ridges. 

§  36.   The  conditions  above  noticed  show  the  deposition 


XI.] 


GEOLOGICAL  STUDIES  IN  PENNSYLVANIA. 


643 


the  deposition 


of  these  rocks  over  an  uneven  subsiding  gneissic  area,  and 
a  conformable  overlapping  of  the  Primal  beds  by  the  suc- 
ceeding Auroral  limestone.  As  described  by  the  writer 
in  1876,  "  they  were  evidently  deposited  over  a  subsiding 
continent,  with  bold  shores  ;  so  that  while  the  Primal  has 
in  places  a  great  thickness,  it  is  elsewhere  very  thin,  or 
entirely  wanting  beneath  the  Auroral,  which  rests  directly 
upon  the  older  crystalline  rocks."  *  The  characters  of 
the  Primal  are  best  seen  farther  to  the  west,  where,  in  the 
broader  part  of  the  basin,  it  is  brought  up  by  undulations 
from  beneath  the  Auroral,  and  appears  as  a  complex 
group  of  considerable  thickness,  v."ith  alternations  of 
quartzites,  argillites,  and  crystalline  schists,  beds  of  iron- 
ores,  and  intercalated  limestone-layers  ;  the  latter  consti- 
tuting, as  well  described  by  Rogers,  beds  of  passage  into 
the  overlying  Auroral  limestone.  Rogers  defined  the 
group  as  a  Primal  sandstone,  with  slates  above  and 
below ;  but  it  is  occasionally  less  simple,  since  what  he 
called  the  Upper  Primal  slates  may  include  interstrati- 
fied  sandstone-beds,  sometimes  of  considerable  thickness. 
Thus,  in  a  section  near  Parkesburg,  on  the  North- Valley 
Hill,  described  by  him,  a  mass  of  200  feet  of  yellow  sand- 
stone is  found,  with  300  feet  of  slates  above,  and  350  feet 
more  below,  lying  between  this  upper  sandstone  and  the 
white  Scolithus-sandstone  beneath,  which  here  measures 
fifty  feet ;  the  section  being  as  follows,  numbered  in  de- 
scending order : — 

Feet. 

0.  Auroral  limestones — 

1.  Upper  Primal  slates  with  sandstone  layers  ....  300 

2.  Yellow  sandstone 200 

3.  Laminated  slaty  beds 360 

4.  Middle  Pr-mal  sandstone,  with  Scolithus     ....  50 

5.  Lower  Primal  slates 300-400 

A  section  at  Chickis,  on  the  Susquehanna,  also  described 
by  Rogers,  gives  a  still  greater  thickness  of  strata  referred 

*  Harpers'  Annual  Record  for  1876,  p.  xcvl. 


.,M»  to  ..eP.n..;t.eW,^o.t.»  se.es  not  ..„. 
exposed.    Wehave,  as  before—  ^  ^^ 

1800 

1.  Upper  Primal  slates.    •••••.•.''*...'       ^7 

2.  White  sandstone dw 

:    :i'S«.n;^*Womh^: : : 

we  Shan  notice  fan^-J^e-ha^^^^^^^ 

Primal  slates  as  seen  el'«™l'»™  " 

f„  Pennsylvania  and  .n  other  Sta^s  ^.^  ^  j 

R  S7.  Since  the  time  7^«" ''Marches  in  various  parts 
JestigationsinPen„sj«  e-ai^^^  ^^^^^ 

of  the  Atlantic  bf ''  ^"^j'^^h  were  known  to  h.m, 
between  the  ancient  gneisses  w  ^^^^  .^^ 

and  the  base  of  the  I'^'^l^'l^  talline  stratified 
localities,  one  or  more  f  J^J  Huronian,  and  of  the 
rocks.  0£  these,  Pf'^''^"?  i*t^hich  have  been  called 
younger  gneisses  and  ■»''=.»-^*'^*JJogical  resemblances  to 
kntelban,  present  certain  mineralog  ^  ^^^^^  ^^  ^^^^^ 
the  schists  o£  the  Lower  Pnmal^^^^  ^^^  ^^^^^^^^ 

interstiatified  with  '^"'i  ov'^f  jf,,  aUtinctly  crystalline 
was  stated  by  Rogers,  more  «^  „„,,,  Rogers    con- 

Sd  thrc^s^^rf.-  -rth^r  s:- 

Sa^lotLrrgralnameof-semi-met. 

morphic  schists."  separates  the  Scolithus- 

I  38.  No  stratigraph.calbreak sop  ^^^^  ^^^^  ^^^ 

Jdstono  from  the  ^'J^^.'^Xmorphic  schists  below 
,vhole  of  these  r""  lltone  great  group.    Th  s  was 
this  horizon  were  included  '» Jfation  of  the  Paleozoic 
described  as  a  d'"'r'''li'oe  of  organic  remains,  was 
series;  but,  from  f*hs  and  from  the  more  ancient 
distinguUhed  alike  ft^J^'^;"™  jj^e  name  of  the  A.ou> 
-      or  so^alled  Hypozoie  g»;~^Kogers,  among  the  rocks 
series.    There  ^f.-^'Ja^  physLl  break,  or  horizon 
of  the  Atlantic  belt,  but    one  p  j 


XI.] 


GEOLOGICAL  STUDIES  IN  PENNSYLVANIA. 


545 


i  not  being 


Feet. 
1800 
27 
300 


)f  the  Lower 
ribution,  both 

his  geological 
I  various  parts 
e  shown  that 
tnown  to  him, 

are,  in  many 
aiine  stratified 
an,  and  oi  the 
ave  been  called 
lesemblances  to 
las  well  as  those 
Auroral,  are,  as 
nctly  crystalline 
3S,  Rogers    con- 
with  portions  ot 
,e  older  gneiss: 

of  "semi-meta- 

tes  the  Scolithus- 
,es,  and  thus  the 
)hic  schists  below 
group.    This  was 

of  the  Paleozoic 

anic  remains,  was 

the  more  ancient 

,ame  of  the  Azoic 

s,  among  the  rocks 

break,  or  horizon 


of  unconformity,  throughout  the  immense  succession  of 
altered  crystalline  sedimentary  strata,"  namely,  that  at  the 
summit  of  the  ancient  or  Hypozoic  gneiss ;  and  "  one 
paleontological  horizon  —  that,  namely,  of  the  already 
discovered  dawn  of  life  among  the  American  strata. 
This  latter  plane  or  limit,  marking  the  transition  from  the 
non-fossiliferous  or  Azoic  deposits  to  those  containing 
organic  remains,  lies  within  the  middle  of  the  Primal 
series  of  the  Pennsylvania  survey ;  that  is  to  say,  in  the 
Primal  white  sandstone,  which,  even  where  very  vitreous, 
and  abounding  in  crystalline  mineral  aggi-egations,  con- 
tains its  distinctive  fossil,  the  Scolithus  linearis." 

§  39.  In  the  opinion  of  Rogers,  the  whole  series  of 
strata  below  the  Levant  sandstone  had,  in  the  southeast- 
ern area,  been  the  subject  of  alterations,  which  had  given 
to  them  the  characters  of  crystalline  rocks.  I  have  else- 
where set  forth  at  some  length  the  views  of  Rogers  on 
this  point,  and  have  shown  that  his  conclusions  with  re- 
gard to  the  so-called  Azoic  rocks  were  not  clearly  defined, 
and  that,  in  his  opinion,  it  was  often  difficult,  if  not  im- 
possible, to  distinguish  between  the  upper  portions  of  the 
Hypozoic  and  certain  parts  of  the  Azoic  series.  It  would 
appear  from  his  descriptions,  and  from  my  own  examina- 
tions in  the  region,  that  portions  of  Huronian,  and  of 
Montalban,  were  by  him  included  in  the  Hypozoic ;  and 
other  portions  of  the  same  or  of  older  rocks,  in  the  Azoic^ 
or  even  in  the  Upper  Primal  slates.  Both  these,  and  the 
Primal  quartzite  itself,  were  by  Rogers  supposed  to  have 
been  changed  into  feldspathic  rocks ;  and  he  has  described 
as  alt-^red  Upper  Primal,  a  great  group  of  such  rocks 
seen  in  the  South  Mountain  to  the  south  of  tlie  Susque- 
hanna, which  we  shall  proceed  to  notice. 

§  40.  Leaving  the  Mesozoic  red  sandstones  at  Gettys- 
burg, and  passing  westward  over  the  South  Mountain,  by 
Caledonia  Spring  to  Chambersbuig,  we  meet  first  with 
a  belt,  more  than  two  miles  wide,  of  crystalline  rocks, 
regarded  by  Rogers  as  in  part  Upper  and  in  part  Lower 


(|P3^* 


m 


I 
fipiiil  PI 

'I 


iHil   I 


i 


111     « 


i 


546 


THE   TACOKIC  QUESTION   IN   GEOLOGY. 


[XI. 


Primal  slates ;  the  latter  represented  by  talcose,  chloritic, 
and  epidotic  schists,  with  diorites,  and  the  former  by  what 
were  called  by  Rogers,  "jaspery  rocks,"  and  "reddish 
jaspery  slates."  These,  which  I  first  saw  with  Dr.  Per- 
sifor  Frazer,  in  1875,  were  found  to  consist  of  petrosilex 
or  compact  orthofelsite,  often  becoming  porphyritic  from 
the  presence  of  crystals  of  feldspar  or  of  quartz.  I  then 
compared  tliem  with  the  similar  rocks  found  along  the 
coasts  of  Massaclmsetts  and  New  Brunswick,  and  on 
Lake  Superior,  all  of  which  I  at  iuat  time  included  in  the 
lower  part  of  the  Huronian,  but  have  since  been  led  to 
regard  as  an  independent  series,  identical  with  the  Arvo- 
nian  of  Kicks ;  which,  in  Wales,  appears  to  be  interposed 
unconformably  between  the  Laurentian  (Dimetian)  below, 
and  the  Huronian  (Pebidian)  above. 

§  41.  To  this  series  also  belongs  a  great  thickness  of 
petrosilex-rocks,  often  porphyritic,  and  associated  with 
small  portions  of  soft,  unctuous  micaceous  schists,  occur- 
ring in  central  Wisconsin,  where  they  overlie  conformably 
a  great  mass  of  vitreous  quartzites,  which,  from  the  inter- 
calation of  similar  micaceous  layers,  apparently  belong  to 
the  same  series  with  the  petrosilex.  These  rocks,  origi- 
nally described  by  Percival  as  altered  Potsdam  sandstone, 
were  by  James  Hall,  in  1862,  referred  to  the  Huronian, 
with  which  they  are  also  classed  by  Irving,  who  has  since 
described  them.*  I  have  recently  examined  these  rocks, 
in  situ,  as  seen  on  the  Baraboo  River  in  Wisconsin,  and 
have  found  them  indistinguishable  from  the  petrosilex- 
beds  of  Pennsylvania  and  of  our  Atlantic  coast,  and  from 
the  typical  Arvonian  of  Wales. 

§  42.  These  petrosilicious  strata,  presenting  many  va- 
rieties in  color  and  in  texture,  have  a  great  thickness  in 
the  South  Mountain,  west  of  Gettysburg,  where  they 
generally  dip  southeastward  at  high  angles.  With  them 
are  seen  in  some  parts,  apparently  interstratified,  thin 

*  See  Geology  of  Wisconsin,  1877,  vol.  ii.,  pp.  501-521;  also  Hunt, 
Azoic  Rocks,  p.  232. 


XI.] 


GEOLOGICAL  STUDIES  IN  PENNSYLVANIA. 


547 


5,  chloritic, 
ler  by  what 
\  "reddish 
bh  Dr.  Per- 
f  petrosilex 
liyritic  from 
,rtz.    I  then 
d  along  the 
ick,  and  on 
jluded  in  the 
3  been  led  to 
ith  the  Arvo- 
be  interposed 
letian)  below, 

;  thickness  of 
isociated  with 
schists,  occur- 
te  conformably 
from  the  inter- 
jntly  belong  to 
•se  rocks,  origi- 
dam  sandstone, 
the  Huronian, 
,  who  has  since 
I'ed  these  rocks, 
Wisconsin,  and 
the  petrosilex- 
coast,  and  from 

anting  many  va- 
at  thickness  in 
■irg,  where  they 
es.  With  them 
,er'stratified,  thin 

601-621;  also  Hunt, 


bands  of  argillite,  with  chloritic  and  epidotic  rocks,  such 
as  I  have  found  with  the  similar  petrosilicious  rocks  on 
Passamaquoddy  Bay,  on  the  Atlantic  coast.  This  crys- 
talline series  is,  to  the  westward,  un  conformably  overlaid 
by  a  belt,  about  a  mile  and  a  half  wide,  of  sandstone,  with 
conglomerates,  generally  with  a  northwestern  dip,  consti- 
tuting what  is  known  as  Green  Ridge.  This  is  followed 
by  a  repetition  of  the  petrosilicious  rocks,  again  with  high 
southeast  dips,  and  by  a  great  mass  of  chloritic  and  epi- 
dotic strata,  overlaid  to  the  westward,  as  before,  by  a 
considerable  thickness  of  Primal  sandstone,  which  dips  in 
that  direction  beneath  the  Primal  slates  and  Auroral  lime- 
stones of  the  Appalachian  valley. 

§  43,  In  this  remarkable  section,  it  is  evident  that  the 
crystalline  rocks,  upon  which  the  Primal  quartzite  rests 
unconformably,  belong  to  one  or  more  older  series,  dis- 
tinct from  the  Laurentian,  and  representing  both  the 
Huronian  and  the  petrosilex  or  Arvonian  series.  I  was 
thereby  confirmed  in  my  opinion,  expressed  in  1871,  that 
the  crystalline  schists  regarded  by  Rogers  in  this  region 
as  altered  Lower  Primal  and  Upper  Primal,  are  both  of 
them  older  than  the  Primal  quartzites,  and  belong  to  one 
or  more  distinct  series.  These  conclusions  were  an- 
nounced in  the  Proceedings  of  the  American  Association 
for  the  Advancement  of  Science  for  1876  (pp.  211,  212), 
and  also  in  Azoic  Rocks  (pp.  18  and  193).  Frazer,  who 
has  since  devoted  much  time  to  the  study  of  the  region, 
agrees  with  me  in  placing  the  crystalline  rocks  of  the 
above  section  in  the  Huronian,  including  under  that  name 
the  accompanying  petrosilex  group;  and  regards  the 
quartzites  as  there  forming  the  basal  member  of  the 
Primal  series.* 

§  44.  From  the  observations  given  in  §  36,  it  is  appar- 
ent that  the  Primal  series  of  Rogers,  where  most  largely 
developed  in  Pennsylvania,  includes  several  repetitions  of 
quartz-rocks,  sometimes  vitreous,  sometimes  granular,  and 

*  Thfese  pr^sent^e  k  la  faculty  des  sciencea  de  Lille,  etc.,  1882^ 


648 


THE  TACONIC  QUESTION   IN   GEOLOGY. 


00. 


occasionally  detrital  and  conglomerate  in  character,  alter- 
nating with  softer  schistose  strata.  This  will  be  farther 
illustrated  in  a  succeeding  chapter,  by  observations  in 
Virginia  and  elsewhpre;  when  it  will  also  appear  that 
repetitions  of  these  quartzites  are  met  with  below  the 
horizon  of  the  Scolithus-sandstone.  In  many  cases,  a 
quartzite,  often  a  conglomerate,  is  found  to  constitute  the 
basal  member  of  the  series,  which  rests  unconformably 
upon  different  groups  of  the  older  crystalline  rocks,— 
Laurentian,  Arvonian,  Huronian,  or  Montalban.  Inas- 
much as  portions  of  the  latter  two  groups  were  by  Rogers 
confounded  with  the  Lower  Primal  slates,  it  will  require 
careful  examination,  in  each  case,  to  determine  whether 
we  have  really  to  do  with  the  older  rocks,  or  with  strata 
belonging  to  his  Primal  series. 

Notwithstanding  the  division  of  the  latter  into  Azoic 
and  Paleozoic,  based  by  Rogers  upon  the  appearance,  in 
the  midst  of  the  Primal,  of  the  Scolithus-sandstone,  it  is 
to  be  remarked  that  the  Primal  slates,  both  above  and 
below  this  horizon,  really  constitute,  with  the  rocks  of 
the  Auroral,  and  a  portion  of  the  Matinal  in  the  south- 
eastern area  of  Pennsylvania,  one  great  continuous  series. 
Similar  schistose  and  micaceous  layers  are  found  inter- 
calated alike  among  the  Primal  quartzites  and  the  Auro- 
ral limestones;  while  the  accompanying  masses  of  slate 
often  include  minor  beds  of  quartzite,  and  others  of  gran- 
ular limestone.  The  intimate  relations  of  these  various 
rocks  were  noticed  by  Rogers,  who  mentions  what  he 
calls  "  the  alternations  of  Primal  slate  and  Auroral  lime- 
stone," and  "  the  limestone  at  the  passage  of  the  Primal 
into  the  Auroral."  The  Lower  Primal  slates  were  else- 
where described  by  him  as  alternations  of  "  talcoid  sili- 
cious  slate,  talco-micaceous  slate,  and  quartzose  micaceous 
rocks,"  usually  schistose,  besides  otl  !r  strata  which  are 
nearly  pure  clay-slate.  Portions  of  the  Matinal,  in  like 
manner,  were  said  by  him  to  be  "  a  semi-crystalline  cluy- 
slate*  partially  talcose   or   micaceous."      Later    studies 


XI.]  GEOLOGICAL  STUDIES  IN  PENNSYLVANIA.  549 


actev,  alter- 
1  be  farther 
jvvations  in 
appear  that 
1  below  the 
any  cases,  a 
onstitute  the 
iconformably 
ine  rocks, — 
alban.  Inas- 
ive  by  Rogers 
Lt  will  require 
mine  whether 
or  witli  strata 

iter  into  Azoic 
appearance,  in 
sandstone,  it  is 
oth  above  and 
I  the  rocks  of 
,1  in  the  south- 
ntinuous  series. 
re  found  inter- 
5  and  the  Auro- 
masses  of  slate 
others  of  gran- 
of  these  varioiis 
utions  what  he 
id  Auroral  lime- 
re  of  the  Primal 
slates  were  else- 
of  "talcoid  sili- 
rtzose  micaceous 
strata  which  are 
Matinal,  in  like 
L-crystalline  clay- 
Later    studies 


have  shown  these  strata  to  abound  in  hydi'ous  micas,  and 
more  rarely  to  contain  talc,  chlorite,  and  related  species. 
Some  beds  in  the  Primal  slates  are  apparently  feldspathic 
in  composition,  since  they  are  changed  by  sub-aerial  decay 
info  clays  resembli»ig  kaolin. 

§  45.  The  continuous  belt  of  Primal  and  Auroral 
rocks  stretching  along  the  southeast  base  of  the  North  or 
Kittatinny  Mountain,  is  bounded  on  the  south,  in  its 
extension  between  the  Delaware  and  Schuylkill  Rivers, 
by  the  so-called  South  Mountain.  Beyond  the  Schuylkill, 
at  Reading,  this  Laurentian  range  is,  so  far  as  known, 
represented  only  by  one  small  mass,  a  little  west  of  the 
town.  Its  disappearance  at  the  Schuylkill,  to  rise  again 
south  of  the  mesozoic  belt,  in  the  northern  part  of  Chester 
County,  permits  a  great  extension  of  breadth  of  the  Pri- 
mal and  Auroral  rocks  to  the  southward,  in  the  counties 
of  Chester,  Lancaster,  and  York,  where  they  appear,  both 
to  the  north  and  the  south,  from  beneath  the  broad  and 
somewhat  irregular  belt  of  mesozoic  sandstone  which, 
from  the  Delaware  to  the  Susquehanna,  crosses  the  State 
in  an  east  and  west  direction.  From  the  Susquehanna  to 
the  line  of  Maryland,  however,  the  trend  of  this  belt  is  to 
the  southwest.  The  Primal  and  Auroral  strata,  along  the 
south  and  east  of  the  mesozoic,  occupy  the  limestone- 
valleys  of  Lancaster  and  York  Counties,  with  which  the 
narrow  limestone  valley  of  Chester  County,  lying  to  the 
eastward,  is,  as  Frazer  has  shown,  continuous. 

§  46.  The  South  Mountain,  which,  as  we  have  seen,  is 
effaced  between  the  Schuylkill  and  the  Susquehanna,  re- 
appears to  the  southwest  of  this  rive' ,  in  the  broad  ridge 
of  crystalline  rocks,  already  described  in  §  40  as  found  in 
Adams  County,  between  the  continuous  limestone-valley 
on  the  northwest,  and  the  mesozoic  on  the  southeast. 
In  tliis  ridge  of  Huronian  and  Arvonian  rocks,  the  Lau- 
rentian has  not  yet  been  recognized.  It,  however,  as 
already  remarked,  appears  in  Chester  County,  betAveen 
the  mesozoic  and  the  Chester  limestone-valley.    In  addi- 


i; 


tj' 


M 


I 


ooO 


THE  TACONIO  QUESTION  IN  GEOLOGY. 


[XI. 


tiun  to  tliis,  I  pointed  out,  in  1876,  the  existence  of  a 
subordinate  Laurentian  axis,  south  of  the  limtstone- 
valley  just  named,  crossing  the  Schuylkill  in  Buck  Ridge, 
near  Consholiocken.*  This  ridge  bears  upon  both  flanks 
the  Montalban  gneisses  and  mica-schists;  while  between 
these  and  the  Laurentian,  on  the  south  side  of  the  axis, 
there  is  seen  on  the  river  an  intermediate  mass  of 
hornblendic  and  chloritic  schists,  with  serpentine,  ensta- 
tite,  and  steatite,  which  may  be  an  intervening  outcrop  of 
Iluronian. 

§  47.  Returning  now  to  tlie  Primal  and  Auroral  rocks, 
the  distribution  of  which  has  been  defined,  we  remark 
that  it  is  chiefly  along  the  border  of  the  mesozoic  belt 
that  the  Primal  schists,  with  their  accompanying  crystal- 
line iron-ores,  already  noticed  (§  26),  are  best  exposed. 
Examples  of  these  ores  are  seen  at  Boyerstown,  and  near 
Reading,  at  Wheatland,  Cornwall,  and  Dillsburg,  on  the 
north  side,  and  at  the  Warwick  and  Jones  mines,  on 
the  south  side,  of  the  mesozoic  sandstone.  Rogers,  in  his 
third  annual  report  on  the  geology  of  Pennsylvania,  in 
1839,  referred  these  iron-ores  to  the  mesozoic  or  "middle 
secondary  red  sandstone "  series,  giving,  as  examples, 
besides  the  mines  just  mentioned  on  the  south  side  of  this 
belt,  the  Cornwall  mine  on  the  north  side.  In  his  final 
report,  in  1858,  however,  he  referred  these  crystalline 
iron-ores  and  their  enclosing  schists  to  the  Upper  Primal 
slates.  He  regarded  the  iron  as  an  original  constituent 
of  the  sediments,  but  supposed  it  to  have  been  re-arranged 
"by  some  agency  connected  with  the  metamorphism  of 
the  strata."  Lesley,  in  1859,  in  his  "  Iron  Manufacturers' 
Guide,"  described  these  same  ores  under  the  head  of 
"  Primary,"  with  those  of  the  gneisses  and  pre-paleozoic 
crystalline  rocks;  at  the  same  time  referring  with  ap- 
proval to  those  who  regard  these  ores  "as  of  middle 
secondary,  and  not  of  primary  age."  Subsequently,  in 
the  same  volume,  he  noticed  the  later  view  of  Rogers 

*  Azoic  Bocks,  page  200. 


QY.  >^ 

xistence  of  a 
[\e  limtstone- 
t  Buck  Uitlge, 
n  both  flanks 
vhile  between 
e  of  the  axis, 
diate  mass  uf 
peutine,  ensta- 
ling  outcrop  of 

Auroral  rocks, 
led,  we  remark 
3  inesozoic  belt 
panying  crystal- 
a  best  exposed, 
stown,  and  near 
)illsburg,  on  the 
[ones  mines,  on 

Rogers,  in  bis 
Pennsylvania,  in 
ozoic  or  "middle 
tg,   as  examples, 
south  side  of  this 
;ide.     In  his  final 
these  crystalline 
the  Upper  Primal 
".ginal  constituent 
3  been  re-arranged 
metamorphism  of 
on  Manufacturers' 
nder  the  head  of 
t  and  pre-paleozoic 
referring  with  ap- 
:es  "as  of  middle 

Subsequently,  m 
er  view  of  Rogers 


XI.] 


GEOLOGICAL  STUDIES  IN  PENNSYLVANIA. 


651 


already  stated,  and  apparently  accepted  it,  at  least  for  the 
ores  of  Warwick,  of  Cornwall,  and  of  Chestnut  Hill, 
where  nuigiietite  is  closely  associated,  in  adjacent  strata, 
with  limunite.  Frazer,  however,  in  187G,  still  niaiiitaiiiod 
the  early  view  of  Rogers  for  the  ores  of  Dillshurg,  iu 
Adams  County,  which  he  describes  as  included  in  the 
mesozoiu  series,*  and  they  are  so  classed  in  MoCreath's 
Report  M  3  (preface,  page  x)  of  the  Second  geological 
survey,  in  1881. 

§  48.  From  my  own  somewhat  extended  studies  of  all 
the  localities  known  along  the  two  borders  of  the  meso- 
zoic  belt  in  Pennsylvania,  I  am  constrained  to  maintain 
the  opinion  expressed  by  me  in  1875,  mat  the  ore-beds 
near  Dillsburg  form  no  exception,  but  that  these,  with 
the  deposits  of  ore  at  Cornwall,  at  Wheatland,  in  the 
vicinity  of  Reading,  and  at  Boyerstown,  on  the  north,  as 
well  as  those  of  the  Warwick  and  Jones  mines,  on  the 
south,  all  belong  to  the  same  ancient  horizon.  That  they 
are  met  with  chiefly  along  the  borders  of  the  mesozoic- 
saudstone  belt,  as  I  then  said,  "  is  due  to  the  fact  that 
these  ancient  ore-bearing  rocks,  from  their  decayed  con- 
dition and  their  inferior  hardness,  have  been  removed  by 
denudation,  except  where  protected  by  the  proximity  of 
the  newer  sandstones,  or  by  eruptive  rocks,  as  is  the  case 
at  the  Cornwall  mine."  f  There,  as  I  have  i)ointed  out, 
the  dikes  from  the  neighboring  raesozoic  area  have  served 
as  barriers,  and  have  preserved  from  erosion  a  great  mass 
of  magnetic  iron-ore. 

§  19.  The  stratigraphical  relations  of  these  ore-bearing 
rocks  serve  to  show  that  they  must  be  referred  to  the 
Primal  schists  which  underlie  the  mesozoic  sandstones.. 
These  latter,  which  are  generally  regaixled  as  of  triassic 
age,  form  a  continuous  belt  from  the  banks  of  the  Hudson 
southwestward  across  New  Jersey  and  Pennsylvania  into 

•  Second  Geological  Survey  of  Penn.,  Report  C,  page  71;  and  Trans. 
Amer.  Inst.  Mining  Engineers,  v.,  133. 
t  Ibid.,  iv,,  320. 


662 


THE  TACONIO  QUESTION  IN  OEOLOOT. 


OD. 


Virginia.  Throughout  this  region,  as  is  well  known, 
theso  newer  rocks  have  everywhere  a  moderate  and  very 
uniform  dip  to  the  northwestward,  of  from  ten  to  thirty 
degiee.s,  and  were  deposited  upon  the  worn  surfaces  of 
the  previously  folded  Primal  and  Auroral  rocks,  which 
have  contributed  largely  to  the  materials  of  the  mesozoic. 
These  older  strata,,  unlike  the  latter,  present  everywhere 
considerable  undulations,  with  dips,  sometimes  at  high 
angles,  alike  to  the  northwest  and  the  southeast.  The 
unconformably  overlying  mesozoic  rocks,  now  themselves 
affected  by  a  gentle  and  pretty  uniform  inclination  to  the 
northwest,  agree  nearly  with  the  older  rocks  in  strike; 
and  the  coincidence  which  thus  appears  between  the 
mesozoic  and  the  northward-dipping  outcrops  oi  the  older 
rocks  readily  explains  how  the  two  have  been  con- 
founded. 

§  50.  In  the  vicinity  of  Dillsburg,  where  numerous 
openings  for  iron-ore  have  been  made,  the  dip  of  the 
enclosing  strata,  so  far  as  observed,  is  to  the  northwest. 
The  same  condition  is  seen  at  Wheatfield,  to  the  east  of 
Cornwall,  where  se/eral  lenticular  masses  of  magnetite 
have  been  mined ;  but  at  Fritztown,  less  than  half  a  mile 
to  the  southward,  the  similar  ore-bearing  strata  dip  to  the 
southeast.  Again,  at  the  Roudenbusch  mine,,  near  Read- 
ing, is  a  bed  of  magnetite  which  had,  in  1875,  been  mined 
for  a  distance  of  480  feet  down  the  slope  of  the  bed ;  the 
dip  being  thirty  degrees  in  a  direction  S.  30°  E.  At  the 
Island  mine,  also  near  Reading,  is  a  similar  opening  for 
ore,  which  had  been  followed  240  feet  on  the  incline, 
with  a  dip  of  forty-five  degrees  to  the  southeast ;  while 
immediately  to  the  north  of  this  opening  is  a  slope  with  a 
still  steeper  dip  to  the  northwest,  on  what  appears  to  be 
the  same  ore-bed ;  indicating  the  presence  of  an  anticlinal 
in  the  ore-bearing  strata.  At  Boyerstown,  still  farther 
east,  where  the  mesozoic  lies  along  the  southeast  flank  of 
the  South  Mountain,  there  is  opened,  at  its  margin,  a 
mine  in  which  the  ore-stratum  had,  in  1875,  been  followed 


,Y.  ^^' 

veil  known, 
ate  au<l  very 
ten  to  thirty 
I  surfaces  of 
roukB,  which 
the  mesozoic. 
t  everywhere 
imes  at  high 
itheast.  The 
[)W  themselves 
lination  to  the 
,cks  in  strike; 
I  between  the 
,ps  oi  the  older 
tve  been  con- 
hero  numerous 
the  clip  of  the 
,  the  northwest. 
.,  to  the  east  of 
as  of  magnetite 
than  half  a  mile 
strata  dip  to  the 
mine,,  near  Read- 
875,  been  mined 
of  the  bed;  the 
S.  SO^E.  At  the 
nilar  opening  for 
t  on  the  incline, 
southeast;  while 
T  is  a  slope  with  a 

vhat  appears  to  be 

,ce  of  an  anticlinal 

:own,  still  farther 

southeast  flank  ot 

.    at  its  margin,  a 
875,  been  followed 


XI.] 


LOWER   TACONIC   ROCKS. 


653 


down  the  slope,  400  feet,  at  an  angle  of  forty-five  degrees 
to  the  east  of  south.  At  the  great  Cornwall  mine,  which, 
like  all  those  above  mentioned,  lies  on  the  northern  bor- 
der of  the  mesozoic,  the  ore-bearing  strata  are  very 
slightly  incliiuHl ;  while  at  the  Jones  mine,  on  the  south- 
ern border,  they  have  a  genoral  inclination  to  the  north- 
ward, and  puss  visibly  beneath  the  adjacent  mesozoic 
sandstone. 

§  51.  The  identity  of  mineralogical  characters  in  all  of 
the  localities  mentioned  is  very  marked.  The  association 
with  the  granular  magnetite,  of  pyrites,  with  portions  of 
copper  and  cobalt,  the  admixture  of  a  greenisii,  granular 
silicate,  apparently  related  to  pyroxene,  and  the  constant 
proximity  to  the  ores,  of  limestone  and  of  serpentine, 
leave  no  doubt  that  we  have  to  do  with  one  and  the 
same  stratigraphical  horizon ;  which,  as  the  observations 
in  many  of  the  localities  show,  is  unconformably  subjacent 
to  the  contiguous  mesozoic  rocks.  It  may  here  be  noted 
that  the  concretionary  structure  of  some  of  the  limestone- 
masses  which  accompany  the  ore-beds  in  these  Primal 
slates,  has  led  to  their  being  confounded  with  the  con- 
glomerate of  limestone  pebbles  often  found  in  the  meso- 
zoic strata  of  the  region.  All  of  the  rocks  which,  in  the 
southeastern  area  of  Pennsylvania  (that  is  to  say,  to 
the  southeast  of  the  Kittatinny  Mountain),  belong  to  the 
Primal  or  Auroral  divisions  of  Rogers,  as  well  as  those 
portions  of  the  Matinal  which  are  not  included  in  the 
First  Graywacke,  or  in  the  small  Ordov'-ian  areas  (§§  31, 
34),  appertain  to  the  Lower  Taconic  series  of  Emmons. 

rV. —  LOWER  TACONIC   ROCKS   IN   VARIOUS    REGIONS.. 

§  52.  The  Lower  Taconic  rocks,  as  seen  in  their  typi- 
cal locality,  the  Taconic  hills  in  William stown  and 
Adams,  Berkshire  County,  Massachusetts,  were  described 
by  Emmons  as  including,  at  the  base,  a  conglomerate  of 
varying  thickness,  resting  upon  the  ancient  gneissic  rocks 
of  the  region,  from  the  ruins  of  which  it  is  derived; 


■lilit 
h 


!=/--  r' 


"7i  Mi& 


^''*'  X 


ItT 


iS^^ 


654 


THE  TACONIC  QUESTION  IK  GEOLOGY. 


IXL 


and  consisting  of  pebbles  and  fragments  of  quartz  and 
feldspathic  rock  in  a  so-called  talcose  paste.  Above  this 
is  found  a  rock  described  as  a  quartziferous  talcose  scliist, 
sometimes  including  needles  of  tourmaline,  and  followed 
by  the  characteristic  Granular  Quartz-rock  of  Eaton. 
This,  like  the  similar  rock  in  Pennsylvania,  has  afforded 
Scolithus  linearis :  a  specimen  from  Adams  being  figured, 
together  with  one  from  Chikis,  Pennsylvania,  by  Hall,  in 
his  "Paleontology  of  Nev/  York,"  vol.  i.,  pi.  1.*  Above 
this  Scolithus-sandsLone,  which  is  100  feet  thick,  is  a 
succession  of  so-called  talcose  slates,  with  two  interposed 
beds  of  quartzite,  one  of  which,  fine-grained,  massive,  and 
jointed,  measures  400  feet  in  thickness ;  the  whole  succes- 
sion appearing  in  Oak  Hill,  arranged  in  a  synclinal  form, 
with  moderate  dips,  and  having  a  thickness  of  about  1200 


feet. 


§  53.  Immediately  succeeding  this,  is  found  the  Stock- 
bridge  limestone  or  marble,  often  dolomitic,  and  having  its 
bedding-planes  in  many  places  marked  by  scales  of  a 
greenish  micaceous  mineral,  called  talc  by  Emmons ;  the 
presence  of  which  j^ives  rise  to  varieties  of  marble  resem- 
bling the  Italian  cipolUno.  The  limestone  is  white  or 
gray  in  color,  sometimes  very  dark,  and  more  rarely  red- 
dish. To  this  mass,  as  seen  on  the  western  slope  of 
Saddle  Mountain,  a  thickness  of  500  feet  was  assigned. 
Succeeding  this  is  a  mass  of  2000  feet  of  sc  ft  slates,  resem- 
bling those  found  below  the  limestone,  and  also  occasion- 
ally interstratifie  .  with  it.  The  limestone  is  said  to  be, 
in  fact,  intercalated  in  a  great  series  of  such  slates,  and  to 
appear  in  similar  relations  throughout  western  New  Eng- 
land and  eastern  New  York.     The  aggregate  thickness  of 

*  These  two  specimens,  and  a  similar  one,  the  locality  of  which  is  not 
given,  are  the  only  ores  figured  by  Professor  Hall  for  the  Scolithus  of  the 
Potsil^m.  This  form,  however,  is  not  known  in  the  true  Potsdam  sand- 
stone, as  seen  in  the  Champlain  and  Ottawa  basins  ;  nor,  so  far  as  I  am 
aware,  on  the  upper  Mississippi ;  through  all  of  which  regions  this  sand- 
stone is  characterized  by  the  very  distinct  form  described  by  Billings  as 
Scolithus  Canadensis.    See  Azoic  Rocks,  pp.  135-139. 


XL] 


LOWER  TACONIC  SOCKS. 


655 


the  whole  series  in  Berkshire  County,  as  above  described, 
was  estimated  by  Emmons  at  about  3700  feet. 

§  54.  The  roofing-slates  of  the  series  are,  according  to 
him,  included  in  the  great  mass  of  so-called  talcose  slates 
above  the  Stockbridge  limestone,  and  are  found,  with 
similar  characters,  from  Massachusetts  to  North  Carolina. 
Elsewhere,  he  mentioned  that  a  band  of  argillites  of 
variable  thickness,  adapted  for  roofing-slates,  is  also  some- 
times found  in  the  schists  beneath  the  limestone.  Emmons 
was  careful  to  distinguish  between  these  Lower  Taconic 
argillites,  and  those  red  and  green  roofing-slates  which  are 
found  in  the  Upper  Taconic.  He  farther  affirms  that  the 
talcose  slates,  with  their  associated  roofing-slates,  are  not 
found  in  the  Upper  Taconic  series. 

§  55.  It  is  well  known  that  throughout  this  belt  of 
Lower  Taconic  rocks  east  of  the  Hudson,  as  well  as 
farther  south,  great  deposits  of  limonite  are  found  in  the 
decayed  schists  of  the  series.  Associated  with  this  is  an 
aggregate  described  by  Emmons  as  an  iron-breccia,  made 
of  fragments  of  quartz  cemented  by  limonite,  which, 
accor'li.iig  to  him,  is  characteristic  of  this  horizon  in  Ver- 
mont, Massachusetts,  Pennsylvania,  Virginia,  North  Caro- 
lina, and  Tennessee.  Such  a  quartziferous  limonite  is  also 
described  by  C.  U.  Shepard  as  found  in  the  same  belt  at 
Kent,  in  Connecticut.*  In  an  iron-mine,  open  in  1875, 
near  Heading,  Pennsylvania,  I  examined  a  similar  aggre- 
gate, holding  nuii\erou8  pebbles  of  white  quartz  in  a  paste 
of  limonite.  At  a  depth  of  sixty  feet,  the  ore-stratum 
being  highly  inclined,  the  limonite  was  replaced  by 
granular  pyrites,  also  holding  quartz-pebbles,  and  it  was 
evident  that  the  alteration  oi  this  bed  of  pyrites  had  given 
rise  to  the  limonite-conglomerate. 

§  66.  The  Lower  Taconic  series,  according  to  Emmons, 
is  as  well  developed  in  the  southern  as  in  the  northern 
United  States.  "  From  the  northern  part  of  New  Eng- 
land it  is  prolonged  southward,  a 'id  upon   the  line  of 

•  Geological  Survey  of  Connecticut,  1837,  p.  23. 


iHS 


656 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


•I     if! 


.prolongation  it  continues  uninterruptedly  for  more  than 
one  thousand  miles."  It  extends,  in  fact,  through  the 
whole  length  of  the  great  Appalachian  valley,  and  is  well 
known  from  Pennsylvania  southwestward  through  Vir- 
ginia and  East  Tennessee  to  Georgia  and  Alabama.  A 
section  of  these  rocks  from  near  Wytheville,  in  the  valley 
of  Virginia,  and  another  near  Harper's  Ferry,  will  be 
found  described  by  Emmons  in  his  "American  Geology," 
part' II.  -  These  resemble  closely  both  that  of  Berkshire 
County,  Massachusetts,  and  those  in  Pennsylvania  given  in 
the  preceding  chapter.  With  all  these  we  may  compare 
a  recent  section  *Jong  the  western  base  of  the  Blue  Ridge, 
in  Virginia,  described  in  a  private  communication  from 
Prof.  W.  M.  Fontaine.  The  granular  quartz-rock  with 
Scolithus,  here  300  feet  thick,  is  separated  from  the  great 
mass  of  limestones  above  by  about  600  feet  of  slates  with 
limonite,  and  is  underlaid  by  more  than  1700  feet  of 
argillites  and  sandstones,  with  intercalatei.1  strata  of 
unctuous  lustrous  schists,  apparently  containing  a  hydrous 
mica,  and  sometimes  decaying  to  kaolin.  In  the  lower 
portions,  which  become  more  quartzose,  are  beds  holding 
in  a  slaty  matrix  pebbles  of  quartz  and  of  feldspa^-^ic 
rocks ;  and  the  base  of  the  section  is  described  as  a  con- 
glomerate made  up  of  pebbles  from  the  eozoic  rocks  of 
the  Blue  Ridge,  towards  >vliich  the  whole  series  dips,  and 
beneath  which  it  seems  to  pass.  The  strike  of  the  Pvimal 
rocks  is  N.  60°  E.,  while  that  of  the  eozoi.  is  N.  30°  E. 
The  lower  portions  of  the  Taconic  series  are  here  some- 
times concealed  by  faults. 

§  67.  It  is  hardly  necessary  to  repeat  that  the  great 
Lower  Taconic  belt,  as  above  defined,  includes  the  Primal 
and  the  Auroral,  together  with  a  portion  of  the  Matinal 
of  Rogers,  in  Pennsylvania,  where  some  localities  were 
examined  and  described  by  Emmons.  In  our  account  of 
these  rocks,  in  that  State,  in  the  last  chapter,  we  called 
attention  to  the  thinning-out  of  the  slates  and  quartzites 
in  some  loc  :  'ities  along  tlie  borders  of  the  deposit,  and 


XI.] 


LOWER   TACONIC   ROCKS. 


[XI. 

lore  than 
•ough  the 
lid  is  well 
ough  Vir- 
ibama,     A 
the  valley 
y,  will  be 

Geology," 
:  Berkshire 
Ilia  given  in 
ay  compare 
Bine  Ridge, 
cation  from 
tz-rock  with 
m  the  gveat 
I  slates  with 
L700  ieet  of 
,eO.   strata   of 
ing  a  hydrous 
In  the  lower 
beds  holding 
of  feldspa^^iic 
bed  as  a  con- 
ozoic  locks  of 
eries  dips,  and 

of  the  Primal 
fi.  is  N.  30°  E. 
are  here  some- 

that  the  great 
ides  the  Pri-nal 
of  the  Matmal 
localities  were 
our  account  of 
apter,  we  called 
1  and  quartzites 
the  deposit,  and 


667 


even  their  concealment  beneath  the  conformably  overlap- 
ping limestone.  We  also  noticed  the  appearance  of  these 
rocks  of  the  Primal  division,  elsewhere,  from  beneath  the 
limestones,  with  a  volume  not  less  than  that  measured  by 
Emmons  and  Fontaine.  The  great  thickness  assigned  to 
the  limestones  of  the  series  in  Pennsylvania  is  to  be 
noted;  and  also  the  consideration  that  some  of  this  ap- 
parent thickness  of  several  thousand  feet  may  possibly  be 
due  to  repetitions.  We  have  also  remarked  the  fact  that 
these  Lower  Taconic  or  Auroral  limestones  are  brought 
up  by  undulations  from  Loneath  the  overlying  rocks  in 
the  central  valleys  or  coves  of  Pennsylvania.  The  same 
condition  of  things  is  met  with  in  Alabama,  where  the 
Auroral  limestones  or  marbles,  with  their  underlying 
slates  and  quartzites,  abounding  in  limonite,  as  shown  by 
Eugene  A.  Smith,  are  exposed  on  the  great  axis  which 
divides  the  coal-basins  of  the  Black  Warrior  and  the 
Cahaba;  and  are  also  brought  to  view  by  a  dislocation 
and  uplift  along  the  southeastern  edge  of  the  latter 
basin.* 

§  68.  Lying  to  the  eastward  of  the  Lower  Taconic  belt 
of  the  Appalachian  valley,  and  generally  divided  from  it 
by  the  range  of  aiicient  crystalline  rocks  to  which  belong 
the  South  Mountain  and  the  Blue  Ridge,  there  are  other 
areas  of  Lower  Taconic  strata  found,  at  intervals,  from 
Georgia  to  New  Brunswick,  often  appearing  as  parallel 
interrupted  belts.  These  are  the  remains  of  a  mantle  of 
these  rocks  once  widely  spread  over  the  older  crystalline 
strata  of  the  Atlantic  slope,  from  which,  after  folding 
and  faulting,  they  have  been  in  great  part  removed  by 
erosion. 

§  59.  One  of  these  Taconic  areas  was,  as  long  ago, as 
1817,  defined  and  mapped  by  Maclure,  who  described  it 
as  "  a  Transition  belt "  extending  from  the  Delaware  to 
the  Yadkin  in  North  Carolina,  having  a  breadth  of  from 

*  See  Hunt  on  Coal  and  Iron  in  Alabama;  Trans.  Amer.  Inst.  Mining 
Engineers,  February,  1883. 


558 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


St  ■; 


-lu. 


two  to  fifteen  miles,  and  a  general  dip  to  the  southeast. 
He  pointed  out  its  course  from  the  Delaware,  passing  by 
Norristown,  Lancaster,  York,  and  Hanover,  in  Pennsylva- 
nia, and  Frederickstown,  in  Maryland,  through  Virginia ; 
noted  its  passage  beneath  the  mesozoic  red  sandstone,  and 
its  termination  in  Pilot  Mountain,  in  Surry  County,  North 
Carolina.  The  rocks  composing  "this  belt  were  described 
by  Maclure  as  consisting  of  granular  quartzite,  granular 
limestone  or  marble,  and  various  slates.*  Through  the 
Lancaster  valley,  as  already  noticed  (§  45),  the  Taconic 
rocks  of  this  eastern  belt  are  connected  with  those  of  the 
Appalachian  valley.  Maclure  also  described  another  area 
of  the  same  rocks  found  on  the  north  branch  of  the 
Catawba,  at  the  base  of  the  Linville  Mountains,  in  Mc- 
Dowell County,  North  Carolina. 

§  60.  Emmons,  who  had  examined  this  belt  near  the 
Schuylkill  River,  in  Pennsylvania,  was  also  acquainted 
with  its  extension  into  North  Carolina,  and  in  his  report 
on  the  geology  of  that  State,  in  1856,  mentions  it  as  one 
of  the  five  areas  of  Taconic  rocks  known  within  its  bor- 
ders, which  are  described  in  that  report.  Professor  Kerr, 
who  has  since  studied  still  farther  the  distribution  of  these 
rocks  in  that  State,  has  delineated  them  on  the  geological 
map  accompanying  his  report  of  1876  These  rocks  pre- 
sent, according  to  him,  "  five  principal  outcrops,  with  two 
or  three  subordinate'  ones,"  which  may  be  regarded  as 
portions  of  these.  Referring  to  his  report  for  details,  it 
may  be  said  that  the  first  or  easternmost  belt  of  these 
rocks  in  North  Carolina,  is  in  part  concealed  under  the 
tertiary  strata  east  of  Raleigh,  but  is  again  seen  west  of 
the  Raleigh  granite-range.  The  second,  a  band  with  a 
breadth  of  from  twenty  to  forty  miles,  extends  from  north 
to  south  across  the  State,  along  the  western  border  of  the 
mesozoic  area.     .  . 


•  Maclure,  Observations  on  the  Geology  of  the  United  States  of  Am- 
erica, with  a  Geological  Map,  etc.,  reprinted  from  the  1st  vol.  of  the  Trans. 
of  the  Amer.  Philos.  ooc,  new  series.    Philadelphia  :  1817;  pp.  42,  43. 


southeast. 

passing  by 
Pennsylva- 
h  Virginia ; 
dstone,  and 
unty,  North 
re  described 
Lte,  granular 
Chrough  the 
the  Taconic 
those  of  the 
another  area 
•anch  of  the 
tains,  in  Mc- 

belt  near  the 
30  acquainted 
in  his  report 
ions  it  as  one 
vithin  its  bor- 
rofessor  Kerr, 
bution  of  these 

the  geological 
lese  rocks  pre- 
n-ops,  with  two 
36  regarded  as 
t  for  details,  it 
t  belt  of  these 
^aled  under  the 
lin  seen  west  of 

a  band  with  a 
ends  from  north 
rn  border  of  the 


mited  States  of  Am- 
1st  vol.  of  the  Trans. 
,:  1817;  pp.  42,  43. 


XI.] 


LOWER  TACONIC  ROCKS. 


659 


§  61.  The  third,  designated  as  the  King's-Mountain 
belt,  and  including,  besides  the  mountain  of  that  name, 
the  elevations  known  as  Crowder's,  Spencer's,  and  Ander- 
son's Mountains,  is  in  the  southern  part  of  the  State,  west 
of  the  Catawba  River ;  stretching  through  Catawba,  Lin- 
coln, and  Gaston  Counties,  and  passing  thence  into  South 
Carolina.  This  third  belt  is  in  the  strike  of  that  traced 
by  Maclure  from  the  Delaware  into  Stokes  and  Surry 
Counties,  in  the  northern  part  of  the  State,  and  is  re- 
garded by  Kerr  as  a  continuation  of  it,  though  interrupted 
for  some  distance  between  the  Yadkin  and  the  Catawba. 

§  62.  The  fourth  is  a  great  belt  which,  like  the  second, 
is  continuous  across  the  State,  along  the  Blue  Ridge  ;  the 
rocks  in  question  passing  from  the  east  to  the  west  side  of 
that  chain  in  the  southwest  part  of  their  extension.  This 
belt,  at  the  Swannanoa  Gap,  is  from  six  to  seven  miles 
broad,  but  has  its  greatest  development  in  the  Linville 
Mountains,  where  it  includes  the  area  of  these  rocks 
noticed  by  Maclure  on  the  north  branch  of  the  Catawba, 
in  McDowell  County,  and  also  an  important  section  de- 
scribed by  Emmons,  on  the  Frenoh-Broad  River,  in  Bun- 
combe County,  to  be  noticed  farther  on. 

§  63.  The  fifth  or  western  area  of  the  Taconic  rocks  is 
confined,  according  to  Kerr,  to  the  southwestern  part  of 
the  State,  into  which  it  extends  from  Tennessee,  including 
the  mass  of  the  Smoky  Mountain  of  the  Unaka  range, 
and  stretches  from  Madison  County,  widening  southward, 
until  it  includes  almost  the  whole  breadth  of  Cherokee 
County,  in  the  southwest  corner  of  the  State.  To  the 
Taconic  of  this  region  belongs  the  well  known  section 
near  Murphy  in  that  county.  The  rocks  of  this  belt,  as 
seen  at  Paint  Rock  on  the  French-Broad  River,  in  Madi- 
son County,  beginning  at  the  Tennessee  line,  are  1  y  Kerr, 
and  by  Safford,  identified  as  a  continuous  part  of  the 
Ocoee,  Chilhowee,  and  Knox  groups  of  the  latter.*     It  is 

*  Kerr.  Report  Geological  Survey  of  North  C"\rolina,  1875,  vol.  I.,  p. 
131,  and  pp.  138, 139. 


!llr 


|:i  fl 


fc;.i 


iw-'.llUfi'"' 


5G0 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


under  these  names  that  Safford  has  described  tlie  Lower 
Taconic  series  of  the  Appalachian  valley,  as  found  in 
eastern  Tennessee,  of  which  the  belt  in  the  southwest 
counties  of  North  Carolina  forms  a  part.  The  Ocoee 
slates,  and  the  Chilhowee  or  Scolithus-sandstone  of  east- 
ern Tennessee,  both  recognized  by  Emmons  as  Lower 
Taconic,  represent  the  Lower  Primal  slates  and  quartz- 
ites,  which,  in  this  region,  have  a  greatly  augmented 
volume.  In  Alabama,  according  to  Prof.  Eugene  A. 
Smith,  the  thickness  of  this  sandstone  is  not  less  than 
2000  feet,  and  that  of  the  underlying  slates,  10,000  feet. 

§  64.  Professor  Kerr,  while  recognizing  in  these  rocks 
the  strata  described  by  Emmons  under  the  name  of  Ta- 
conic, gave  them,  as  he  tells  us  in  his  report  of  1875, 
provisionally,  the  name  of  Huronian,  both  designations 
appearing  in  thu  legend  of  the  accompanying  map.  In 
explanation  of  this,  it  is  to  be  remarked  that  he  then 
included  all  of  the  more  ancient  crystalline  rocks  of 
North  Carolina  under  the  head  of  Laurentian,  which  he 
divided  into  Lower  Laurentian  (also  called  granite  in  his 
engraved  sections)  and  Upper  Laurentian.  The  latter 
name  (at  one  time  used  by  the  geological  survey  of  Can- 
ada to  designate  an  entirely  different  group  of  rocks,  the 
Norian)  was  by  Professor  Kerr  applied  to  the  series  of 
younger  gneisses  and  micaceous  and  hornblendie  schists 
(with  included  beds  of  chrysolite  or  olivine-rock),  which 
is  the  Montalban  series  of  the  author. 

These  rocks,  in  1877, 1  found  to  rest  in  Mitchell  County, 
North  Carolina,  directly  upon  the  ancient  granitoid  gneisses 
of  the  Laurentian,  the  Huronian  being  absent.  The  true 
pkxe  of  this,  as  appears  from  multiplied  observations,  is 
below,  not  above,  the  Montalban,  and  it  moreover  differs 
entirely  in  its  lithological  characters  from  the  Lower 
Taconic  rocks,  which  are  found  above  the  Montalban  hori- 
zon. It  remains,  however,  to  be  determined  whether  true 
Huronian  and  Arvonian  rocks  may  not  occur  in  parts  of 
North  Carolina,  and  may  not  be  represented  by  some  of 


ZI.] 


LOWER  TACONIC  ROCKS. 


561 


the  greenstones  and  the  feldspar-porphyries  noticed  by- 
Professor  Kerr  as  found  in  parts  of  the  Montalban  (Upper 
Laurentian)  area  of  the  State. 

§  65.  The  Taconic  strata  of  North  Carolina  are  de- 
scribed by  Kerr  as  resting  in  some  places  upon  the 
granitic  rocks,  and  in  others  upon  the  upper  or  Montal- 
ban series,  and  in  part  made  up  of  its  ruins.  Pebbles  of 
the  older  crystalline  rocks,  in  which  I  have  recognized 
both  gneiss  and  mica-schist,  are  often  met  with  in  the  con- 
glomerates of  the  series.  In  the  quartzites  of  the  second 
belt  at  Troy,  in  Montgomery  County,  occur  the  silicious 
concretions  regarded  by  Emmons  as  organic,  and  described 
by  him  under  the  name  of  Paleotrochis.  Other  beds  of 
granular  quartzite  are  flexible,  constituting  the  variety 
known  as  itacolumite.  With  these,  besides  the  usual 
argillites  and  unctuous  schists,  are  found  beds  of  pure 
massive  pyrophyllite,  which  was  by  Emmons  described  as 
agalmatolite,  and  has  been  mistaken  for  steatite  or  com- 
pact talc,  beds  of  which  are  also  met  With  in  this  series. 
The  schists  are  sometimes  graphitic,  and  even  include 
beds  of  graphite,  ^s  in  the  King's-Mountain  belt.  The 
quartzites  of  the  series  frequently  contain  cyan^te  and 
rutile,  and  also  include,  as  in  Pennsylvania,  both  mag- 
netic and  specular  iron-ores,  as  will  be  noticed  farther  on, 
in  the  account  of  these  rocks  in  South  Carolina.  The 
characteristic  limestones  —  often  becoming  marbles — and 
the  limonites  of  epigenic  origin  here,  as  in  other  regions, 
mark  the  series. 

§  66.  I  have  elsewhere  described  these  rocks  as  seen 
by  me  in  the  fourth  belt  in  North  Carolina,  on  the  north 
branch  of  the  Catawba,  near  Marion,  in  McDowell  County, 
where  they  were  first  seen  by  Maclure ;  *  and  have  noticed 
the  granular  quartz-rock,  often  becoming  thinly  bedded 
and  flexible,  the  unctuous  micaceous  schists,  the  limon- 
ites, and  the  limestones,  as  having  all  the  characters  of 

*  Proc.  Boston  Soc.  Nat.  Hist.,  1878,  xix.,  p.  277,  and  Azoic  Rocks, 
pp.  207,  208. 


^„^  TACONIC  QUESTION  «■  "■^'-O''^' 

1     • 


[XI. 


/ 


1  -a  A  section  in  this 
these  rocks  as  seen  in  P«™f  J^rm  Springs,  in  Bun- 
same  belt  favtl.ev  southwest,  a^  Wa  ._!  ^^^^  be 
combe  County,  des«nbed  .^y  1^^^  ^^,^^  ,„„ks  m  the 
compared  with  sm.lar  B«<;t'^  °  „  Pennsylvania,  and  in 
Appalachian  valley  m  V>rg'W»' ^  ;^^  ,,hich  latter  he 
BeLhire  County,  Massachusetts        ^^^^,  „i,h  a  wes^ 

especially  compared  •»•    ™  ^„,„be  County  uncontorma- 
Jtd  inclination,  rest  '"^unc".  ^^^^^  „f  the 

bly  upon  the  eastward-dipping  c  y  ^  ,„„giomerate 

bL  Uidge.    They  P-»^^^\*;  succession  o£  slates 
^ith  a  talcose  P''^''^' *°"°';!^„  Jar  and  vitreous  quartz- 
with  interposed  masses  ot  granui  tliickness  o£ 

to  and  Wo^c-^'^t^^^'^eTd  W)  feet  of  limestone, 
about  2400  ieet.    To  «rese  succeed      ^^^  ^,^,^,^ 

foUovvod  by  more  than  150  tee^  ^^^^^^  ^^p^r- 

hesides  a  farther  mass  of  comer  ^^^^.^^^  ^^^ 

fectly  exposed.    Emmons  notes 'n^^^^^^^,,  ,^hich  is 
development  of  l^f^'*?  f"^;,    Z  L  strata  belovv  the 

Sitr.;."  ?—  -5-  •■«"'-"■"■  "•* 

sachusetts.*  ,     ,     unconformable  superpo- 

5  67.  In  connection  ™'*  "^^  "  yer  crystalline  rocks, 

silon  of  the  Taeo"io^^,nrV»th  C^^^^^^^^  and  in  New 
Emmons  has  noted,  both  mjoit  the  Tacom 

York,  the  appearance  m  ^om*  P'  ,^  ^nd  concludes  that 
strata,  of  granitic  ''f  .^l^'^^^^y^derlying  floor,  ex- 
thev  are  portions  of  the  J"«B"'  ,  ^be  Taconic.    Of 

;':'ed  byL  folding  -ddc—n  of  th^^^^^^^^^^  ^^^, 

certain  interposed  bands  1 «  «»y«        ^^^\  careful  exam- 
.     .     ",  gard  them  as  interlammated  r^^^^^  ^^      ^^^^  „^ber  will 

.      Jtion  of  the  '^''l.-f  "\"' '^Tp  imary  rocks  are  under- 
„snlt  in  the  conviction  that  the  p       J        ^^^^  ^th  the 

lying  and  older  '""^t'chthy  geographically  separate."t 
/edimentary  rocks  which  *ey  g^^^  ^^^^^  ^^  ^^  ^ 

#  American  Geology,  II-,  P-**' 


y. 


XI.] 


LOWER  TACONIC   ROCKS. 


)03 


ition  in  this 
^gs,  in  Bun- 
855,  may  he 
rocks  in  the 
rania,  and  in 
Ach  latter  he 
,,  with  a  west- 
l  unconforma- 

rocks  of  the 
conglomerate 

jsion  of  slates, 
itreous  quartz- 
ite  thickness  ot 
.t  of  limestone, 
Igrained  slates, 
se  rocks,  imper- 
.ction  the  larger 
lerates,  which  IS 
strata  belovr  the 
bat  the  rocks  ot 
logically  indistm- 
lliamstown,  Mas- 

'ormahle  superpo- 
cvystalline  rocks, 
>lina  and  in  Nexv 
,,ong  the  Taconic 
,nd  concludes  that 
derlying  floor,  ex- 
^  the  Taconic.    ^^ 
,e  geologist  might 
,^t  a  careful  exam- 
s  to  each  other  will 
,y  rocks  are  undei- 
.Jnnection  with  the 

phically  separate.  T 
an  Geology,  W-.P- 26. 


In  a  later  book,  his  "  Manual  of  Geology,"  published  in 
1860,  Emmons  reproduces  the  figures  of  the  sections 
noticed  above,  but  gives  with  them  only  very  brief  de- 
scriptions. He  there  states  that  the  maximum  thickness 
of  the  Lower  Taconic  rocks  may  be  about  5000  feet. 
Above  the  basal  conglomerate,  which  is  sometimes  absent, 
there  are  generally,  according  i^  his  later  statement, 
three  masses  of  quartzite,  divided  by  slates,  the  upper  of 
these  being  often  vitreous,  and  the  lower  granular  in  tex- 
ture. The  roofing-slates  are  said  to  occur  in  the  upper 
part  of  the  mass  of  slates  which  overlies  the  limestone. 

§  68.  Passing  southward  from  North  Carolina,  the 
Lower  Taconic  rocks  were  by  Tuomey  traced  across 
South  Carolina,  and  into  Georgia  and  Alabama.  He  de- 
scribed them  as  a  series  of  quartzites,  with  talcose  slates 
and  marbles,  well  displayed  in  the  Spartanburg  district, 
in  the  northern  part  of  South  Carolina.  They  are  also 
met  with  in  Pickens,  the  most  western  district  of  the 
State,  in  what  is  probably  a  continuation  of  the  fourth 
belt  of  North  Carolina,  and  extend  across  Pickens  into 
the  contiguous  portions  of  Georgia.  The  belt  just  men- 
tioned has  there  a  considerable  development  in  Habersham 
County,  where  it  has  been  seen  by  the  writer,  and  also  in 
the  adjacent  counties  of  Hall  and  Union,  a  region  in  which 
a  considerable  number  of  diamonds,  supposed  to  occur 
in  this  series,  have  been  found.  There  appears  also  to  be 
another  and  more  eastern  belt,  which,  according  to  C.  U. 
Shepard,  passes  from  South  Carolina  into  the  counties  of 
Lincoln  and  Columbia  in  Georgia.  In  the  former  of  these 
occurs  Graves  Mountain,  known  to  mineralogists  as  a 
locality  of  pyrophyllite  and  cyanite,  as  well  as  of  re- 
markable crystals "  of  rutile  and  of  lazulite,  all  of  which 
are  found  with  the  granular  quartzites  of  the  series.* 

§  69.  These  rocks  were  the  subject  of  extended  and 
careful  studies  by  the  late  Oscar  Lieber,  whose  examina- 
tions were  chiefly  confined  to  the  area  in  the  northern 

*  Amer.  Jour.  Science,  1859,  xxvil.,  p.  36. 


564 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


Bn» 


part  of  South  Carolina,  where,  according  to  him,  they  are 
best  seen  at  and  near  King's  Mountain,  in  York  District, 
and  occupy  a  region  about  twenty-one  miles  long  and 
from  four  to  seven  miles  wide  in  York,  Spartanburg,  and 
Union  districts.  This  region  is  the  southward  prolonga- 
tion and  terminus  of  the  third,  or  King's-Mountain,  belt 
of  North  Carolina,  which  we  have  described  as  passing 
southward  from  Gaston  County,  and  as  being,  in  the 
opinion  of  Kerr,  the  continuation  of  the  belt  which  from 
the  Yadkin  River  is  traced  northeastward  to  the  Chester 
and  Lancaster  valleys  of  Pennsylvania,  and  thence  into 
the  great  Appalachian  valley. 

§  70.  The  rock  most  characteristic  of  this  series  is, 
according  to  Lieber,  the  granular,  more  or  less  schistose 
quartzite,  which,  with  its  associated  iron-ores  and  slates, 
he  compared  to  the  similar  rock  described  by  Eschwege, 
from  the  province  of  Minas  Geraes,  in  Brazil,  as  a  chloritic 
or  schistose  quartz-rock.  This,  from  its  occurrence  at 
Mount  Itacolumi,  near  Villa  Rica,  was  by  Eschwege 
called  "  itacolumite,"  ^  name  which  was  also  adopted  by 
Humboldt  and  Claussen  for  these  and  related  rocks  as  a 
whole,  but  is  now  commonly  given  only  to  the  flexible 
and  elastic  variety  of  the  quartzite,  the  "elastic  sand- 
stone "  of  Martius.  This  variety,  however,  is  exceptional 
alike  in  Brazil  and  in  our  Lower  Taconic  series ;  and  the 
designation  of  itacolumite  was  by  Lieber  applied  not  only 
to  the  whole  of  the  quartzite,  but  to  its  interstratified 
schists  and  limestones,  which  he  described  as  the  Itacolu- 
mitic  group  or  series. 

§  71.  These  rocks,  on  lithological  grounds,  were  con- 
jectured by  Lieber  to  be  the  stratigraphical  equivalents  of 
the  Itacolumite  or  diamond-bearing  series  of  Brazil,  and 
of  the  similar  rocks  described  by  Jacquemont,  and  later 
by  Claussen,  as  occurring  in  the  diamond  region  of  India, 
being  the  Lower  Vindhyan  series  of  the  present  geologi- 
cal survey  of  that  country.  He  also  noticed  its  probable 
relation  to  the  rocks  found  by  Helmersen  and  Hofmann 


XI.J 


LOWER  TACONIC  ROCKS. 


5G5 


m,  they  are 
rk  District, 
8  long  and 
^nburg,  and 
a  prolonga- 
luntain,  belt 
L  as  passing 
eing,  in  the 
b  which  from 
,  the  Chester 
L  thence  into 

ihis  series  is, 
less  schistose 
es  and  slates, 
by  Eschwege, 
l1,  as  a  chloritic 
occurrence  at 

by  Eschwege 
so  adopted  by 
ited  rocks  as  a 

to  the  flexible 

"elastic  sand- 
:,  is  exceptional 

series;  and  the 
vpplied  not  only 
;8  interstratified 
I  as  the  Itacolu- 

)unds,  were  con- 
sal  equivalents  ot 
es  of  Brazil,  and 
emont,  and  later 
region  of  India, 
e  present  geologi- 
ticed  its  probable 
sen  and  Hofmann 


in  Russia,  in  the  southern  Urals,  which  they  had  described 
as  identical  with  the  Itacolumite  series  of  Brazil,  and 
wliich  have  since  been  found  to  be  dianiantiferous.  I 
have  elsewhere  discussed  at  some  lenrrth  tlio  liistory  of 
these  rocks,*  which  are  again  noticed  farther  on,  in  §  208. 

§  72.  Lieber's  studies  are  to  he  found  in  liis  four  annual 
reports  of  the  geology  of  South  Carolina,  puhlished  in 
1856-60.  With  the  third  report  there  appears,  as  a  sup- 
plement to  the  first  three,  an  essay  on  the  Itacoluniitic 
series,  resuming  his  conclusions  and  ohservations  up  to 
the  year  1859.t  This  same  essay  was  also  published  in 
German  in  1860.:^ 

The  studies  by  Lieber  are  the  more  interesting  and  in- 
structive as  they  are  the  work  of  a  student  trained  in  a 
foreign  school,  and  were  made  without  any  reference  to 
the  preceding  investigations  of  Maclure,  Eaton,  Emmoi  i, 
or  Rogers,  and  apparently  without  the  knowledge  that 
these  rocks  extended  to  the  north  of  the  Carolinas.  As 
his  reports  are  very  rare,  and  hut  little  known,  I  have 
thought  it  desirable  to  give  in  the  following  pages  an 
abstract  of  his  observations.  In  the  four  annual  reports 
already  noticed,  together  with  the  included  supplement, 
Lieber  proposed  to  describe  the  ancient  stratified  rocks  of 
the  State,  and  successively  corrected  and  enlarged  his 
descriptions,  by  collating  which  we  are  enabled  to  frame 
a  connected  statement  of  his  views.     Lieber  divides  the 

*  Report  of  the  Smithsonian  Institution  for  1882;  Review  of  the 
Progress  of  Geology. 

t  The  Itacolumite  and  its  associates,  comprising  observations  on  their 
geological  importance  and  their  connection  with  the  occurrence  of  gold; 
a  Contribution  to  the  (Jeologic  Chronology  of  the  Southern  Alleghanies, 
supplementary  to  Reports  I.,  II.,  and  III.,  by  O.  M.  Lieber,  state  geolo- 
gist, Columbia,  S.  C,  18r)0.  This,  though  having  a  separate  title,  is 
paged  consecutively  (pp.  77-149)  with  Report  III.,  published  in  1858, 
witli  which  it  forms  one  volume.  The  relations  of  gold  to  the  Itacolu- 
mite, and  to  other  rocks,  are  considered  in  a  subsequent  part  of  the  same 
volume,  pp.  153-220. 

t  The  German  edition  of  Lieber's  essay  appears  in  the  Gangstudien 
of  Von  Cotta  and  Herrm.  Miiller;  dritter  Band,  drittes  und  viertes  Heft, 
pp.  309-507.    Freiburg,  1860 


,„B  TACOKIC  QUESTION   IN  OEOLOQV. 


t^ 


6G0  ,     ,, 

r,    .    '  ^^  tl.rpe  nfli'ts,  namely,  tue 
e,ystaUine  rocks  ot  tbo  State  «Uo  «27»  „,:,,„„„,„„,itio 

Itaoolu.uitic  gi'"«P  |»'^1  ^'' "'For  the   fl.-»t-na.uea  o,- 

„-,aaie'one  of  these  »  ""Xs  ft t„taius  rocks  closely 
.,t  a  natural  group. '""  ""^^^^^^^^^  „»«,ciated. 
„Uicaa,>a  everywhere  "'""^  «'\„  n,„  Klug's-Mouutau. 
«  73.  His  descnpuo  .9  am  y  I  ,^^^^^  ,i„|,„„,i 

,c|iou,  as  B-''/"«T^''^:rgt^l  map.  with  an  i.leal 
i„  5  «9.  and  of  wuch  a  8°°'  8«'  ,  ^  ^n.).  A  de»er>pt.on 
Bcotiou.  is  given  ,u  l''-'!"  "  "^  <-[  .^  displayed,  was  atter- 
i„  Ueport  l.,ut  tl";;'^-""^,f  "afmttllygiven,withson,o 
wards  corrected  iu  Uc,o  t  II.  an^  i^J^  l^^,,,,a«S  *" 

bered  in  descending  order : - 

1    Banded  blue  crystalline  limestone. 

I  Abed  of  5;-^-S£ar  layers  of  catawbarlte  (an  aggregate 

3.  Talcose  slate,  ^'""  '|^ '   > 

t»Sn=='.orW.,.o...=»* 

variety.  ^^^.       „j  micaceous  l^«™'^^l*\''^\.r     ' 

,,  Spceular  ^f  J^^^'  ^^^^^^^^^^^^^^^ 

.         5  74.  Beneath  these,  Lieberpiac  ^^.^^.^i.^e,  hovn- 

Jic  division,  clay-Blate    '^l^l\j,  of  which  wevo 

blende-slate,  S^''''\^''tZTeZ  roo\.s-     He  describes  a 
coniectnred  by  him  to  be  igneous  r  ^^^.^^^  ^^^^^^ 


>QY. 


po. 


XI.) 


LOWER  TACONIO  IlOCKa. 


507 


8,  namely,  the 
b-Itacolumitio 
ivat-niuneil  i>r 

tUo  distinuti^'ii 
rock*  closely 

I. 
iugs-Moimtiuu 

e  luive  deline.l 

p,  vvitli  an  iileal 

A  descviptiou 

ayed,  was  aftei- 
given,witli8i""o 

substituting  tlio 
id  adding   »«»"« 
,on,  whicli  repre- 
by  Lieber,  num- 


wbarlte  (an  aggregate 

anded,  sometimes  with 
rs  of  the  flexible,  elastic 

hematite    and  quartz, 
e  replaces  hematite. 

iually  into  the  quartzUe 

iiv  bis  8ub-ltacolu- 
be,  mica-slate,  bovu- 
,,,e   of   wbicb  wevc 
,k8.    He  describes  jv 
e  gray  variety  wttU 
Jt  from  tbe  co.u.e 
of  tbe  State,  and  is 
cbists  bolding  browu 


iron-ores  derived  from  [jyrites.  Those  various  rocks  luivc, 
iu  his  o[)inion,  no  necessary  rehition  to  those  above  them, 
hut  are  simply  tlie  strata  which,  in  different  parts,  unchu-- 
lie  the  Itacolumitic  series.  Little  is  said  about  the 
undorlyinf]f  elay-slate  and  talcose  slate,  botii  of  which  may 
perhaps  belong  to  the  Itacolumitic  series.  To  this  all 
the  others  were  referred,  with  the  possible  exception  of 
the  upper  or  blue  limestone,  which  was  provisionally 
designated  as  super-Itacolumitic,  because  it  is  unlike  the 
marbles  below,  and  also  is  apparently  above  the  horizon 
of  the  gold-veins,  which  are  common  to  the  inferior  rocks 
of  the  Itacolumitic  series. 

§  75.  No  measurements  of  the  several  members  of  the 
series  are  given  by  Lieber,  but  as  seen  at  King's  Moun- 
tain, he  says,  "  its  thickness  will  probably  equal  nearly  a 
mile."  As  represented  in  the  engraved  section  in  Report 
I.  (plate  v.),  it  is  highly  contorted,  and  in  some  places 
shows  inverted  dips,  tlie  strike  being  between  north  and 
northeast.  No  direct  evidences  of  organic  life  are  seen  in 
the  series,  if  we  except  the  forms  observed  by  C.  U. 
Shepard  in  the  upper  blue  limestone  at  the  Broad-River 
quarry  in  York  District,  and  by  him  supposed  to  be  im- 
pressions of  stems  of  Equiseta,  with  swelling  nodes.* 
This  description  recalls  tlie  distinctly  nodose  character 
exhibited  by  the  so-called  Scolithus  of  the  Primal  quartz- 
ite  of  Pennsylvania,  and  the  cylindrical  forms  in  the 
Auroral  limestone  and  its  accompanying  strata  elsewhere, 
which  I  have  compared  with  them  (§  34).t 

§  76.  The  quartzites  of  the  series  present  the  charac- 
teristics which  we  have  recognized  in  those  of  the  Primal 
series  elsewhere,  being  sometimes  conglomerate,  and  at 
other  times  massive,  compact,  concretionary,  or  granular  ; 
often  with  an  admixture  of  a  foliated  mineral,  which  gives 
them  a  laminated  character,  and  assimilates  them  to  the 

*  Shepanl,  Report  to  the  Swedish  Iron  Manufacturing  Company, 
Charleston,  1854;  cited  by  Lieber,  Rep.  H.,  p.  8?. 
t  Azoic  Rocks,  pp.  137,  138,  206. 


I 


I.  ^ 


.  "I 


«! 


.1'! 


1   'I 


i    t 


i,l-  ? 


5G8 


THE  TACONIO  QUESTION  IN   GEOLOGY. 


[XI. 


older  crystalline  schists.  This  interposed  mineral  is,  ac- 
cording to  Lieber,  sometimes  a  mica,  and  at  other  times 
chlorite  or  talc.  We  have  seen  that  the  schistose  strata 
of  this  series  in  Pennsylvania,  and  in  North  Carolina,  are 
sometimes  chloritic,  or  contain  the  species  venerite,  a 
copper-chlorite  (ante,  page  357) ;  while  at  other  times 
they  consist  wholly  or  in  part  of  a  hydrous  mica  (damour- 
ite  or  sericite),  pyrophyllite,  or  true  talc.  All  of  these 
species  are  probably  confounded  by  the  common  epithet, 
"  talcose,"  applied  to  these  rocks,  though  true  talc  is  com- 
paratively rare.  We  have  also  noticed  the  occurrence  in 
the  schists  of  this  series,  in  Pennsylvania,  of  serpentine, 
of  amphibole,  and  of  garnet.  Cyanite  and  rutile,  the 
latter  in  large  and  fine  crystals,  are  not  unfrequently 
found  in  the  granular  quartzites  of  the  series,  and  stauro- 
lite  is  also  met  with.  The  lower  limestone  of  Lieber's 
section  sometimes  contains  tremolite.  It  is  marked  by 
dark  bands,  and  frequently  by  talcose  seams,  which  render 
it  unfit  for  use  as  a  marble.  In  King's  Mountain,  this 
limestone  is  traversed  by  auriferous  veins,  and  the  quartz- 
ites and  schists  of  the  series  are  also  auriferous,  and 
constitute  the  chief  gold-bearing  rocks  of  the  southern 
States. 

§  77.  The  iron-ores  of  the  series  in  South  Carolina, 
other  than  the  iimonites,  are  by  Lieber  included  under 
three  varieties.  First,  an  aggregate  of  magnetite  with 
talc,  called  by  him  catawbarite,  the  talc  in  some  cases  dis- 
appearing ;  second,  a  schistose  silicious  hematite,  described 
as  a  specular  schist,  in  which  foliated  hematite  takes  the 
place  of  mica.  This,  by  the  substitution  of  magnetite 
for  hematite,  passes  into  a  rock  which,  from  a  locality  in 
Braidl,  has  been  named  itabirite.  These  ores  occur  in 
beds  or  lenticular  masses ;  the  latter  two  varieties  in  the 
quartzite,  and  the  catawbarite  in  the  Oalcose  schists  of  the 
series. 

§  78.  The  hydrous  iron-ore  or  limonite,  so  abundant 
in  this  series  elsewhere,  received  but  little  notice  from 


XI.] 


LOWER  TACONIC   ROCKS. 


569 


Licber.  He  mentions,  ho  trover,  its  occurrence  in  the 
King's-Moinitain  region  intercalated  in  decaying  talcose 
shvtes,  with  red  clays  and  an  underlying  stratum  of  kaolin. 
The  limonite  is  here,  as  in  parts  of  Pennsylvania  (§  26), 
associated  with  anhydrous  red  oxyd,  and  Lieber  conceives 
this,  and  some  other  similar  deposits  in  the  region,  to  have 
originated  from  the  hydration  and  alteration  of  specular 
'iron-ore,  or  of  magnetite.  This  view,  which  has  been 
frequently  advanced  by  others,  is,  however,  inconsistent 
with  the  known  permanency  and  unalterable  character  of 
the  anhydrous  oxyds  of  iron,  and,  moreover,  with  the 
well  known  origin  of  the  hydrous  ore  by  epigenesis  from 
pyrites  or  from  siderite.  Lieber  himself  mentions  else- 
where the  occurrence  of  beds  of  limonite,  intercalated  in 
the  talcose  slates  of  the  series,  and  due  to  the  alteration 
of  masses  of  pyrites,  which  is  found  unchanged  in  depth. 

§  79.  We  owe  to  Prof.  Henry  Wurtz  a  valuable  paper, 
published  in  1859,  on  the  mineralogy  of  the  northward 
extension  of  the  King's-Mountain  belt,  as  seen  in  Gaston 
and  Lincoln  Counties  in  North  Carolina.  He  there  no- 
ticed the  itacolumite-rock,  and  its  supposed  relations  to 
the  diamond,  described  the  anhydrous  iron-ores  under  the 
names  of  magnetite-schist  and  hematite-schist,  and  more- 
over what  he  called  a  pyrites-schist.  He  farther  observed 
great  interstratified  beds  of  limonite,  which  he  regarded 
as  derived  from  the  alteration  of  a  pyrites  that  is  found 
unchanged  in  the  deep  workings  of  these  ores.  With 
them,  and  elsewhere  in  the  talcose  schists  of  the  region, 
he  observed  the  frequent  occurrence  of  black  earthy  man- 
ganese-oxyd,  containing  much  cobalt  and  some  nickel.* 
It  is  worthy  of  notice  in  this  connection  that  both  the 
magnetites  and  the  limonites  of  this  horizon  in  Pennsyl- 
vania generally  contain  more  or  less  cobalt,  as  shown  in 
numerous  analyses  by  Genth  and  McCreath.  The  pyrites 
found  at  the  Cornwall  iron-mine  in  Pennsylvania  is  also 
cobaltiferous. 


r      1   '1- 


V,.;^1 


*  Amer.  Jour.  Science,  xxvii.,  pp.  24-31. 


iU 


Ei^&imm'^ 


li>    f 


II;  ii 


670 


THE  TACONiC  QUESTION  IK  GEOLOGY. 


[XI. 


The  magnetic  and  specular  ores  found  so  abundantly  in 
the  Primal  series  of  Pennsylvania,  and  already  described 
at  length,  are  evidently  the  equivalents  of  those  described 
by  Lieber  and  by  Wurtz,  and  constitute  an  important 
and  widely  extended  ore-bearing  horizon.  The  silicate 
mingled  with  the  magnetites  in  many  of  the  Pennsylvanii; 
deposits,  is  probably  more  nearly  related  to  pyroxene  than 
to  talc  in  composition.  The  mineralogy  of  all  of  these 
deposits  demands  careful  study,  inasmuch  as  they  belong 
to  a  distinct  and  well  marked  horizon  of  crystalline  rocks, 
the  importance  and  geological  significance  of  wliicli  has 
hitherto  been  to  a  great  extent  overlooked  by  American 
geologists. 

The  Itacnlumitic  series  of  Lieber,  with  its  estimated 
approximative  thickness  of  5000  feet,  being  evidently 
the  Lower  Taconic  of  Emmons,  it  remains  to  be  seen 
whether  the  upper  blue  limestone,  provisionally  regarded 
by  Lieber  as  distinct,  really  belongs  to  a  higher  horizon, 
or  is  a  member  of  the  series.  In  the  latter  case,  the 
upper  schists  and  the  roofing-slates  of  the  Lower  Taconic 
are  unrepresented  in  this  area,  and  have  probably  been 
removed  by  erosion.  The  best  locality  for  the  study  of 
the  whole  series  in  South  Carolina  is,  according  to  Lieber, 
at  Limestone  Springs,  in  the  Spartanburg  district. 

§  80.  In  this  connection  mention  should  be  made  of 
the  occurrence  of  several  narrow  belts  of  Lower  Taconic 
rocks  folded  in  the  gneiss  of  the  Highlands  east  of  tlie 
Appalachian  valley,  in  northern  New  Jersey,  where  they 
have  been  carefully  studied  and  described  by  Cook,  and 
are  well  seen  in  the  Pohatcong  and  Muscanetcong  valleys. 
They  also  extend  into  southeastern  New  York,  where 
little  is  known  of  their  distribution,  and  where  they  have 
been  confounded  with  the  older  Laurentian  rocks,  into 
which  they  were  supposed,  by  Nuttail,  Mather,  and  H.  D. 
Rogers,  to  graduate.*  In  New  Jersey,  where  Cook  has 
shown  the  fallacy  of  this  view,  the  Auroral  limestones, 

*  Hunt,  Azoic  Rocks,  pages  40,  42. 


JY.  ^^• 

bundantly  in 
,dy  describee! 
,ose  described 
an  important 
The  silicate 
Pennsylvania 
pyroxene  than 
)f  all  of  these 
xs  they  belong 
ystalline  rocks, 
5  of  which  has 
id  by  American 

li  its  esfi  mated 
Dcing  evidently 
lins  to  be  seen 
Lonally  regarded 
higher  horizon, 
latter  case,  the 
B  Lower  Taconic 
e  probably  been 
for  the  study  of 
ording  to  Lieber, 
g  district, 
ould  be  made  of 
J  Lower  Taconic 
lands  east  of  the 
ersey,  where  they 
3ed  by  Cook,  and 
icanetcong  valleys. 
New  York,  where 
d  where  they  have 
•entian  rocks,  into 
Mather,  and  H.  D- 
y,  where  Cook  has 
Auroral  limestones, 

kO,  42. 


XI.] 


LOWER  TACONIC  EOCKS. 


671 


associated  with  limonites,  and  often  overlaid  with  slates, 
are  found  resting  directly  on  the  gneiss,  or  with  a  thin 
intervening  layer  of  the  Primal  sandstone.  These  strata 
are  much  folded  and  faulted,  and  sometimes  present  over- 
turned flexures,  giving  the  whole  succession  an  eastward 
inclination.*  All  of  these  rocks  above  the  gneiss  are,  in 
accordance  with  the  classification  of  Rogers  in  Pennsyl- 
vania, referred  by  Cook  to  the  infra-Trenton  portions  of 
the  Champlain  division.  The  relations  of  the  Green-Pond 
Mountain  conglomerate,  found  in  this  region,  will  be  no- 
ticed farther  on. 

§  81.  The  parallel  belts  of  Lower  Taconic  rocks  found 
east  of  the  Blue  Ridge,  in  the  southern  States,  and  the 
final  disappearance  of  these  rocks  beneath  the  tertiary  to 
the  east  of  Raleigh,  show  that  they  were  once  widely 
spread  over  the  floor  of  the  more  ancient  crystalline  rocks 
which  now  form  the  Atlantic  belt.  To  the  north  of  New 
York,  where  this  belt,  greatly  contracted  between  the 
James  and  the  Hudson  Rivers,  again  broadens,  we  might 
look  for  farther  areas  of  Lower  Taconic  rocks  iu  New 
England,  and  in  the  provinces  lying  farther  to  the  north 
and  east.  We  find,  in  fact,  to  the  east  of  the  Green 
Mountains,  in  Vermont,  a  series  of  limestones  with  soft 
micaceous  slates,  which  have  been  compared  with  the 
Lower  Taconic,  and  may  perhaps  represent  it.  To  this 
horizon  may  also  not  improbably  belong  the  considerable 
areas  of  argillites,  often  roofing-slates,  found  in  the  prov- 
ince of  Quebec,  to  the  north  of  Lake  Memphremagog, 
extending  to  Melbourne,  and  occupying  what  I  have 
called  the  Windsor  basin.  These  argillites  overlie  the 
Huronian  schists,  and  are  themselves  unconformably 
overlaid  by  Silurian  limestones,  which  repose  alike  upon 
the  argillites  and  upon  the  Huronian  series. 

§  82.  Farther  east,  in  Maine,  are  areas  of  argillites, 
and  others  of  quartzose  conglomerates,  limestones,  and 
soft  talcose  schists,  which  were  declared  by  Emmons  to 

*  Cook,  Geology  of  New  Jersey,  1868,  pp.  70, 144. 


if 


n 


ii 


(J 


672 


THE  TACONIO  QUESTION  IN  GEOLOGY. 


[XI. 


resemble  the  Lower  Taconic  rocks  of  western  Massachu- 
setts, and  to  rest  unconformably  upon  the  ancient  niica- 
schists  and  gneisses  of  the  region.  This  series,  whicli 
inchides  the  limestones  of  Rockland  and  of  Camden,  has, 
according  to  Emmons,  a  thickness,  in  the  latter  locality, 
of  2000  feet,  and  is  uy  him  regarded  as  belonging  to  the 
Lower  Taconic ;  to  which,  moreover,  he  refers,  with  much 
probability,  many  of  the  silicious  and  argillaceous  schists 
of  this  part  of  Maine.  The  limestones  and  associated 
rocks  of  C;imberland,  Rhode  Island,  are  also  supposed  by 
Emmons  to  belong  to  the  same  horizon.*  These,  the 
present  writer  has  not  yet  personally  examined. 

§  83.  In  southei'n  New  Brunswick,  as  I  have  pointed 
out,  there  are  found  numerous  exposures  of  rocks  closely 
resembling  those  of  Camden.  They  have  been  much 
eroded,  but  are  seen  at  several  points  along  the  coast,  as 
at  Fryc's  Island,  the  peninsula  of  L'Etang,  Pisarinco,  and 
the  mouth  of  the  River  St.  John.  At  this  last  locality,  a 
section  along  the  Green-Ilead  road,  on  the  right  bank  of 
the  river,  is  described  in  detail  by  Matthew  and  Bailey  in 
the  report  of  the  geological  survey  of  Canada  for  1870. 
The  strata,  with  a  general  southeast  dip  of  about  fifty 
degrees,  have  a  breadth,  across  the  strike,  of  4100  feet,  of 
which  1500  are  limestones,  and  the  remainder  chiefly 
quartzites,  often  schistose,  with  argillaceous  and  some- 
what micaceous  schists,  and  occasional  hornblendic  layers. 
Considerable  masses  of  conglomerate,  with  silicious  and 
calcareous  pebbles,  are  also  included  in  the  series,  tiie 
members  of  which  are  not  improbably  repeated  by  dislo- 
cations. The  limestones,  of  which  there  appear  to  be 
several  masses  two  or  three  hundred  feet  in  breadth,  are 
in  part  distinctly  crystalline  and  white,  or  banded  with 
blue  and  gray  colors,  and  in  part  finely  granular,  gray- 
ish, schistose,  and  sometimes  concretionary.  They  are 
frequently   magnesian,   and    occasionally   contain    small 

*  Emmons,  Agriculture  of  New  York,  I.,  97-101,  and  Amer.  Geology, 
II.,  20-22  ;  also  Hunt,  Azoic  Rocks,  179. 


iGY.  wfc*. 

rn  Massaclni- 
ancient  nuc;i- 

series,  whieU 

Camden,  lias, 
latter  locality, 
onging  to  the 
jrs,  with  much 
laceous  schists 
and  associated 
50  supposed  by 

*     These,  the 

ined. 

I  have  pointed 
3f  rocks  closely 
ve   been    much 
ng  the  coast,  as 
r,  Pisarinco,  and 
s  last  locality,  a 
le  right  bank  of 
w  and  Bailey  in 
;anada  for  1870. 
p  of  about  fifty 
,  of  4100  feet,  of 
emamder  chiefly 
ceous   and  some- 
)rnblendic  layers. 
nth  silicious  and 

II  the  series,  the 
■epeated  by  dislo- 
ere  appear  to  be 
et  in  breadth,  are 
5,  or  banded  with 
ly  granular,  gray- 
onary.    They  are 
[ly   contain    small 
Jl,  and  Amer.  Geology, 


XI.] 


LOWEU   TACONIC   ROCKS. 


573 


masses  of  yellow  serpentine,  and  a  silvery-white  mica. 
Portions  of  the  limestone  are  apparently  colored  by  a 
carbonaceous  matter,  and  a  bed  of  impure  schistose 
graphite,  which  has  not  the  crystalline  aspect  of  the 
Laurentian  graphites,  is  mined  in  these  rocks  near  the 
citj'  of  St.  John.  These  limestones  have  yielded  to  Sir.  J. 
W.  Dawson  the  remains  of  Eozoiin  Canadense.  The  argil- 
laceous beds,  sometimes  schistose,  and  occasionally  graph- 
itic, wliich  lie  between  tlie  quartzite  and  the  limestones, 
closely  resemble  those  found  in  similar  associations  in  the 
Taconian  areas  already  noticed. 

§  83  A.  [The  rocks  on  tlie  southern  slope  of  the  Cobe- 
quid  Hills,  at  the  head  of  the  Bay  of  Fundy,  belong  to 
the  same  series  as  those  of  the  St.  John.  Nearly  verti- 
cal in  attitude,  and  unconformably  overlaid  by  carbonifer- 
ous strata,  they  were  long  since  described  by  Dawson 
as  "  a  metamorphic  series,"  supposed  to  be  of  paleozoic 
age.*  They  consist  of  a  great  underlying  mass  of 
quartzite,  often  granular,  with  massive  beds  of  granular 
white  limestone,  black  or  olive-colored  argillites,  often 
lustrous,  and  a  soft  greenish  or  grayish,  apparently  argil- 
laceous rock.  These  strata  are  intersected  by  great  veins, 
often  brecciated  in  structure,  and  filled  with  sparry  ferrous 
carbonates  of  varying  composition,  sometimes  nearly  pure 
siderite,  and  including  portions  of  crystalline  hematite  and 
magnetite.  The  carbonates  of  these  veins  near  the  sur- 
face are  changed  into  limonite,  and  have  been  extensively 
mined  at  Londonderry,  Nova  Scotia.  I  have  there  found 
evidences  of  contemporaneous  deposition  of  iron-ores  in 
tliin  layers  of  crystalline  hematite  interbedded  with  the 
granular  limestones.] 

§  84.  This  succession  of  crystalline  limestones,  quartz- 
ites  and  slates,  in  New  Brunswick  and  Nova  Scotia  is 
clearly  older  than  the  un crystalline  sandstones  and  shales 
of  Lower  Cambrian  (Menevian)  age,  which,  with  their 
characteristic  fauna,  are  at  St.  John  found  to  be  in  prox- 

*  Dawson,  Acadian  Geology,  2d  ed.,  p.  682. 


[hi   ■: 


1  I0i 

'■    I''  :■■■       f' 


I      i  ^ 


I'li'^'i!':'. 


1J: 


1') 


674 


THE  TACONIO  QUESTION  IN  GEOLOGY. 


[XI. 


imity.  The  latter  strata  appear  to  be  in  part  made  up  of 
the  ruins  of  the  older  schists,  and  in  one  section,  beds  of 
quartzite  and  conglomerate,  believed  to  belong  to  the 
limestone  series,  occur  between  the  Menevian  and  the 
underlying  Huronian  strata.  A  mile  or  two  away,  how- 
ever, the  limestone  series  is  seen  to  rest  upon  red  grani- 
toid gneiss,  regarded  as  Laurentian ;  and  was  itself  de- 
scribed, in  the  report  just  mentioned,  as  an  upper  member 
of  the  Laurentian  series.  The  evidence  above  adduced 
shows  that  we  have  here  a  great  system  resting  uncon- 
formably  alike  on  Laurentian  and  Huronian,  and  at  the 
same  time  wholly  distinct  from  the  Lower  Cambrian. 
From  these  facts,  ami  from  its  close  resemblance  to  the 
Lower  Taconic  of  Maine,  and  of  western  New  England, 
it  was  in  1875,  by  the  preset' t  writer,  referred  to  the 
Taconic  series.*  A  great  mass  of  similar  limestones  and 
marbles,  with  soft  micaceous  schists,  described  by  Murray 
as  occurring  in  Newfoundland  between  the  gneisses  and 
the  fossiliferous  Cambrian,  may  not  improbably  represent 
the  Lower  Taconic.f 

§  85.  As  we  go  northward  in  the  Champlain  valley, 
the  Lower  Taconic,  which  is  seen  in  southern  and  central 
Vermont,  at  the  western  base  of  the  Green  Mountains, 
passes  beneath  newer  strata.  From  thence  northeast- 
ward, we  have  no  certain  evidence  of  the  existence  of  this 
series  between  the  latter  and  the  belt  of  crystalline  strata 
of  Huronian  age,  which  may  be  traced  along  the  south- 
east side  of  the  St.  Lawrence  valley,  to  a  point  a  little 
farther  east  than  the  meridian  of  Quebec,  where  the 
crystalline  rocks  disappear  beneath  the  surrounding  pale- 
ozoic strata.  If,  however,  we  pass  westward,  we  find  in 
Hastings  County,  north  of  the  eastern  extremity  of  Lake 
Ontario,  a  considerable  area  occupied  by  quartzites,  con- 
glomerates, limestones,  micaceous  slates,  and  argillites, 
resembling  closely  those  of  the  various  Taconian  areas. 

*  Proc.  Bos.  Soc.  Nat.  Hist.,  xvi.,  TjOO  ;  and  Azoic  Rocks,  pp.  170-180. 
t  Hunt,  Amer.  Jour.  Sci.,  1870,  vol.  I.,  p.  86. 


€. 


XI.] 


LOWER  TACONIC  ROCKS. 


;  made  up  of 
tion,  beds  of 
■long  to   th.e 
vian  and  the 
0  away,  how- 
011  red  grani- 
was  itself  de- 
ipper  member 
bove  adduced 
resting  uncon- 
an,  and  at  the 
yer   Cambrian, 
(iblance  to  the 
New  England, 
eferred   to  the 
limestones  and 
ibed  by  Murray 
tie  gneisses  and 
jbably  represent 

lamplain  valley, 
lern  and  central 
reen  Mountains, 
iience   northeast- 
existence  of  this 
crystalline  strata 
along  the  south- 
o  a  point  a  little 
lebec,  where  the 
surrounding  pale- 
■ward,  we  find  in 
ixtremity  of  Lake 
jy  quartzites,  con- 
3S,  and   argillites, 
s  Taconian  areas. 

,oic  Rocks,  pp.  n«-l80. 


These  strata,  whicli  rest  unconformably  alike  upon  the 
Laurentian  and  Huronian  rocks  of  the  district,  are  them- 
selves arranged  in  several  synclinals,  with  moderate  dips, 
and  are  unconformably  overlaid  by  the  fossiliferous  lime- 
stones of  the  Trenton ;  the  lower  members  of  the  Cham- 
plain  division  being  absent  throughout  this  region.  The 
conglomerates  include  pebbles  from  both  of  the  under- 
lying groups.  Crystalline  dolomites,  constituting  mar- 
bles, are  found  in  the  series,  and  above  them,  a  mass  of 
about  1000  feet  of  fine-grained,  grayish  and  bluish,  earthy 
and  somewhat  schistose  limestones ;  the  whole  series 
being  estimated  at  3800  feet.  These  rocks,  which  were 
first  particularly  described  by  Thomas  Macfarlane  (then 
of  the  geological  survey  of  Canada),  in  1864,  were  subse- 
quently known,  in  the  reports  of  the  survey,  as  the 
Hastings  series ;  and  were  by  Logan,  in  1866,  compared 
with  the  micaceous  limestone-series  of  eastern  Vermont 
(§  81).  In  1875,  the  writer,  after  an  examination  of  the 
three  regions,  compared  the  rocks  of  the  Hastings  series 
with  the  similar  rocks  of  southern  New  Brunswick,  and 
of  Berkshire  County,  Massachusetts,  and  described  them 
as  Lower  Taconic*  Xt  may  here  be  mentioned  that 
areas  of  Montalban  gneisses,  and  mica-schists  occur  in  the 
vicinity  of  the  Taconian  rocks  of  Hastings  County,  in 
Ontario. 

§  86.  These  rocks  are  not  destitute  of  direct  evidences 
of  organic  life,  having  furnished  remains  of  Eozoon  Cana- 
dense^  which  have  been  described  and  figured  by  Dawson. 
Numerous  specimens  of  this  have  been  found  in  Tudor, 
"imbedded  in  an  impure,  earthy,  dark  gray  limestone, 
with  which,  and  with  carbonaceous  matter,  the  cavities 
of  the  white  calcareous  skeleton  are  filled " ;  unlike 
those  of  the  Eozoon  from  the  Grenville  series  on  the 
Ottawa,  which  are  generally  filled  with  serpentine  or 
pyroxene.  Dawson  farther  noticed,  in  some  of  the  impure 
dark-colored  limestones  of  the  Hastings  series  from  Maduc, 

■      *  Azoic  Rocks,  pp.  170-172,  and  p.  177. 


1  it   .1 ,  ■»  yi .  i' 


■m 


ji  ^ 


676 


THK   TACONIC   QUESTION    IN   GEOLOGY. 


m. 


II  i. 


"fibres  and  gnumles  of  carbonaceous  matter  which  do 
not  conform  to  the  crystalline  structure,  and  present 
forms  quite  similar  to  those  which,  in  more  modern  lime- 
stones, result  from  the  decomposition  of  algse.  Though 
retaining  mere  traces  of  organic  structure,  no  doubt 
would  be  entertained  as  to  their  vegetable  origin  if  they 
were  found  in  fossiliferous  limestones."  He  noticed  also 
a  similar  limestone  from  the  same  vicinity,  which  is 
apparently  "a  finely  lanunated  sediment,  and  shows  per- 
forations of  various  sizes,  somewhat  scalloped  on  the 
edges,  and  filled  with  grains  of  rounded  silicious  sand." 
Other  specimens  from  the  same  region  are  said  to  present, 
on  their  weathered  surfaces,  indications  of  similar  circular 
perforations,  having  the  aspect  of  Scolithus  or  worm- 
burrows.  Some  of  these  markings  from  jNIadoc  were  sub- 
sequently figured  by  Dawson,  and  designated  "annelid- 
burrows,"  with  the  remark  that  "  there  can  be  no  doubt 
as  to  their  nature."  *  These  are  as  yet  known  only  by  a 
few  transverse  sections,  and  cannot,  therefore,  be  com- 
pared with  the  cylindrical  markings  referred  to  Scolithus 
and  to  Monocraterion,  in  the  Taconic  quartzites  and  lime- 
stones of  the  Appalachian  valley  (§§  34,  62). 

§  87.  Brooks  described  in  1872  an  area  of  rocks  in 
St.  Lawrence  County,  New  York,  lying  along  the  northern 
base  of  the  Adirondacks.  They  include  the  Caledonia 
and  Keene  iron-mines  of  that  region,  and  appear  as  a  series 
of  folded  strata,  with  a  northeast  strike,  resting  in  apparent 
unconformity  upon  reddish  Laurentian  gneiss.  The  rocks 
in  question  consist  of  granular  quartzite,  crystalline  lime- 
stone, and  a  greenish  schistose  rock  described  as  magne- 
sian.  A  bed  of  quartzite  is  interstratified  with  the  lime- 
stones, which  include  treraolite  and  are  overlaid  by  the 
soft,  greenish,  gray-weathering  schists,  to  which  succeed 
the  micaceous  and  earthy  red  hematites  in  lenticular 
masses,  intercalated  with   similar  schists  and  masses  of 

*  Dawson  ;  The  Dawn  of  Life,  pp.  110,  139  ;  aad  Hunt,  Azoic  Rocks, 
pp.  171-177. 


'iw 


GY.  .  *^ 

ter  wliicli  do 

and    present 

modern  lime- 
JgjB.  Though 
are,   no   doubt 

origin  if  they 
le  noticed  also 
nity,  which    is 
and  shows  per- 
alloped   on  the 

silicious  sand." 
s  said  to  present, 
■  similar  circular 
lithus  or  worm- 
jSIadoc  were  suh- 
:Tnated  ^'annelid- 
can  be  no  doubt 
known  only  by  a 
.erefore,  be  com- 
vred  to  Scolithus 
lartzites  and  Ume- 

t,52).  ^     . 

area  of  rocks  m 
along  the  northern 
ide  the  Caledonia 
i  appear  as  a  series 
resting  in  apparent 
gneiss.    The  rocks 
te,  crystalline  lime- 
escribed  as  magne- 
Lfied  with  the  lime- 
are  overlaid  by  the 
5   to  which  succeed 
Itites  in  lenticular 
lists  and  masses  ot 
laad  Hunt,  Azoic  lUKks. 


XI.] 


LOWER  TACONIC  ROCKS. 


577 


quartzite ;  a  friable  sandstone,  sometimes  conglomerate, 
overlying  the  whole.  White  quartzo-feldspathic  veins 
occur  in  the  lower  portion  of  the  limestone.  Emmons, 
who  described  this  locality  in  1842,  and  did  not  observe 
the  lower  quartzite,  referred  the  overlying  conglomerate 
to  the  Potsdam,  and  supposed  the  hematite,  the  limestone, 
and  the  greenish  rock  (by  him  called  serpentine)  to  be 
all  alike  erupted  plutonic  masses.  The  observed  thick- 
ness of  the  series,  as  there  exposed,  is,  according  to 
Brooks,  not  less  than  700  feet,  and  its  entire  volume  prob- 
ably much  greater.  Although  they  were  by  Brooks  com- 
pared with  the  Lower  Taconic  of  Emmons,  I  was  disposed, 
in  writing  of  these  rocks  in  1877,  to  regard  them  as  a  part 
of  the  Laurentian.  Tliey  were,  at  that  time,  compared 
with  the  crystalline  limestones,  with  interstratified  quartz- 
ites  and  conglomerates,  found  in  Bastard  in  Ontario.* 
Farther  consideration  leads  me  to  suspect  that  these  rocks 
of  St.  Lawrence  County  are  really  an  outlier  of  Taconian. 

In  comparing  these  rocks  in  Maine,  New  Brunswick, 
Nova  Scotia,  Ontario,  and  northern  New  York  with  the 
similar  rocks  in  the  Appalachian  valley,  and  elsewhere 
southwards,  it  should  be  remembered  that  in  these  latter 
regions  the  strata,  in  many  cases,  present,  at  their  outcrops, 
soft  materials,  the  results  of  sub-aerial  decay ;  whereas 
only  their  harder  underlying  portions  are  seen  in  the  eroded 
regions  farther  northward.  These  varying  conditions  of 
outcrops  of  similar  crystalline  rocks  in  different  geo- 
graphical areas  have  already  been  discussed  at  length  in 
Essay  VII. 

§  88.  That  the  fauna  of  the  Cambrian,  as  seen  in  the 
Menevian  beds  of  our  eastern  coast,  or  in  the  so-called 
Potsdam  which  forms  the  base  of  the  Cambrian  in  Minne- 
sota and  in  Wisconsin,  marks  the  dawn  of  organic  life, 
will  now  scarcely  be  maintained,  even  uy  those  who  ques- 

*  Brooks  ;  Anier.  Jour.  Science  (3),  iv.,  pp.  22-26  ;  Hunt,  Azoic 
"Rbiks,  pp.  148  and  218;  and  Emmons,  Geology  of  the  Northern  District 
of  New  York,  pp.  92,  98. 


^      1514!     f: 


■:f5:kvtt;i;':|ilM 


'i;  'i 


14  'i    * 


iif 


m 


THE  TACONIO  QUESTION  IN  GEOLOGY. 


txi. 


678 

show  tlie  existence,  beneath  tlu3i«         '     •        ti,e  place 
*:ewherc,  of   '"-"j-^r '«  ^Thie  i.  found 
which  we  l'»™  »«'«"''? '°„£  Lake  Superior,  a  scries  of 
aong  the  ""■■''"tJ;ls  analtes%,ieh  tl>e  writer, 
nuartzites,  impure  l'""^.^*"™;' "  These  had  been,  by 

?„  1873,  called  the  Am2k'g;7^_^^^^^  „£   «„    g^cat 

Logan,  regarded    »^  *«    '°';,  Copper-bearing  series  o 
Keweenian  or  8o-caled  .'JPP"^'i878,  also  attempted 

the  region.    Tbc  -"  "^^^  ,'J,Lnltones,  and  limestones 

to  show  that  the  o™?!"""    „°  A  'deriving  uneonformably 
of  the  so-called  Nlp-gonfoup,  overly^  ^g^^  _^^^^^  ^.^^,^^._ 

the  Animikie,  are  rot  the  •«  .     j,,^  g<,,Uou  exam- 

which,  so  tar  as  "-  ev^^c     So'ded    y^^^ 
ined  by  Logan  and  l"^!,'''  *  ^  maintained  by 

goes,  -gl>';^->r  olrs. torn  ifthological  cons.dera- 
some,  or,  as  neiu  uj  .    -i  # 

.ions,  of  a  more  "^"'^J'''^^  ,^,  distinctness  of  which 
5  89.  The  Ammikie  group.  ^^[ntained,  has  smcc 

from  the  overlying  ^f^'^'^XZ^elX,  and  shown  to 
been  traced  '^f  ^'^f.  \f  i"ri,ontal  sandstones  of  the 
underlie  """""'"'"''''^I'i  as  belon-ring  to  the  Potsdam 
St.  Louis  River,  regarded  »«  be'°^=  ^     a,^  Animilae 

0  Cambrian  of  the  ^^fl^re  t  uu  onformably  upon  the 
quartzites  and  ^^^'^'^^^^Z  borizon  of  the  Lower 
Huronian  series,  w°uld  occupy  .^  ^^^^  ^^.g,^^,,    ( 

Taeonic.    The  writer    »»"'^;'y„„e  ota  (in  the  vicinity 
this  series,  near  Thomson,  in  Ml  ^^^^.^^  ^^,„„eous 

„£  which  they  afford  ;»°fl"S  f  Sded  to  J.  W.  Dawson 

concretions,  one  of  f  ^*J^'J'%he  granular  quartz.tes 

;        the  remains  of  a  ^eratose  sp  nge^  J^J^^^,^^  ,,,„ 

or  sandstones  of  t^''  sene'  ^^  described  b5 

'  •  Azoic  Rocks,  PP- 238-241. 


observations 
,ho  westward, 
ig    the   phi^^ 
lere  is  found, 
or,  a  scries  of 
icli  the  writer, 
,  had  been,  by 
of    the    great 
Ming  series  of 
also  attempted 
,  and  limestones 
'  unconformably 
Lt  newer  rocks; 
.leseHion  exam- 
r  Tluuider  Bay, 
8  maintained  by 
ogical  considera- 

actness  of  which 
ntained,  has  since 

3II,  and  shown  to 
jandstones  of  the 
r  to  the  Potsdam 
^,„the  Animikie 
ormably  upon  the 
izon  of  the  Lower 
n  the  argillites  ot 
ta  (in  the  vicinity 
amerous  calcareous 
to  J.  W.  Dawson 
granular  quartzites 
'xningledwithma^ 
3S,  as  described  bj 
it  should  be  meli- 
us of  the  Menominee 
n  1846,  referred  b} 

241. 


XI.] 


LOWER  TACONIO  R0CK8. 


679 


Houghton  and  Emraona  to  the  Taconic  system.*  Tliere 
is  reason  to  believe  that  tliese  rocks  of  the  Menominee 
region  which,  as  described  by  Brooks  and  Piunpelly,  in- 
clude great  deposits  of  iron-ores  and  murbles,  and  appar- 
ently differ  much  from  the  Huronian  in  character,  are,  as 
8up[)osi'd  by  Irving,  identical  with  the  Animikie  rocks. 

§  90.  [The  publication,  by  the  United  States  geological 
survey,  in  1883,  after  the  above  was  first  printed,  of 
Irving's  report  on  the  Copper-bearing  rocks  of  Lake 
Superior,  together  with  information  since  gathered  from 
other  sources,  throws  much  additional  light  on  the  ques- 
tion of  Huronian  and  Taconian  in  this  region.  Irving 
then  announced  his  conclusion  from  the  essential  identity 
between  the  Animikie  rocks  (which  have,  according  to 
him,  a  thickness  of  10,000  feet)  and  those  of  the  Penokie 
range  in  Wisconsin,  and  their  close  resemblance  to  the 
Iron-bearing  strata  of  the  Marquette  and  Menominee  dis- 
tricts, that  the  whole  of  these  constitute  one  great  geologi- 
cal series. 

[These  conclusions  I  have  been  enabled  to  verify,  hav- 
ing, by  the  courtesy  of  Prof.  N.  H.  Winchell,  examined  his 
collections  of  rocks  from  Minnesota,  and  been  allowed 
the  same  privilege  for  the  collections  from  Minnesota  and 
the  northern  peninsula  of  Michigan,  got  by  Dr.  Rominger, 
who  has,  moreover,  permitted  me  to  consult  his  unpublished 
report  of  geological  work  in  these  regions  in  1881-84. 
The  Granitic  and  Dioritic  groups  of  his  published  report 
of  1878-80  are  by  him  regarded  as  plutonic  rocks,  in 
the  former  of  which  he  embraces  alike  gneisses  and  strati- 
form granites,  and  the  transversal  granitic  masses  found 
in  the  dioritic  group.  This  latter  includes  both  massive 
and  schistose,  more  or  less  chloritic  varieties,  and  is 
intimately  associated  with  the  serpentines  of  the  region, 
which  apparently  form  a  part  of  his  dioritic  group. 

[Resting  in  some  cases  upon  this  group,  and  in  others 
upon  the  granitoid  rocks,  is  a  great  system  divided,  in  as- 

*  Emmons,  Agriculture  of  New  York,  i.,  p.  101. 


ff»;  ■    \     .  I    \ 


680 


THE  TACONIC  QUESTION  IN  GEOLOOY. 


[XI. 


m^4 


ivil!- 


cending  order,  by  Roiningcu-  in  1880,  into  a  Quartzite 
group  (which  includes  a  Marble  series),  an  Iron-<jre  group, 
and  an  Arenaceous-slate  group,  all  of  which  appear  chjsely 
connected.  The  system  comprises  heavy  beds  of  quartz- 
ite, often  schistose  and  with  conglomerates,  interstratilied 
and  overlaid  by  argillites  of  various  colors,  with  graphitic, 
hydro-micaceous  or  sericite  slates,  beds  of  jasper,  of  hema- 
tite, and  magnetite,  either  pure  or  disseminated,  and,  in 
the  upper  portion,  limonite  and  siderite.  The  limestones 
form,  in  the  upper  part  of  the  quartzite  division,  great 
masses  of  white  crystalline  marble,  sometimes  with  mica 
and  tremolite  and  sahlite  ;  at  other  times  they  are  reddish, 
or  dull  and  compact.  The  iron-ores  appear  to  be  in  two 
horizons,  one  below  and  one  above  a  great  body  of  lime- 
stone. To  the  latter  are  referred  the  ores  of  the  Gogebic 
and  Menominee  districts,  and  to  the  former  those  of  Mar- 
quette and  Felch  Mountain,  with  which  those  of  Vermil- 
ion Lake,  in  Minnesota,  appear  to  be  identical.  The  argil- 
lites which  overlie  the  latter  are  those  seen  in  the  St.  Louis 
River  and  at  Thomson,  Minnesota,  which  are  by  Rominger 
compared  with  argillites  at  L'Anse  and  Huron  Bay.  The 
iron-bearing  series  at  Vermilion  L^ke,  as  described  by 
Rominger,  and  shown  in  his  collectio  is  very  like  that  of 
the  Taconian  in  the  Appalachian  region.  Rominger  there 
found  no  representative  of  the  dioritic  group ;  but,  to  the 
south,  an  area  of  rock  described  by  him  and  by  Irving  as 
olivine-gabbro,  which  extends  to  Duluth.  This,  as  seen 
by  the  writer  at  the  latter  point,  where  it  is  apparently 
overlaid  by  the  Keweenian,  has  the  characters  of  the 
granitoid  norites  of  the  Norian  series  in  New  York  and 
Quebec] 

§  90  A.  [The  mica-schists,  sometimes  with  gray 
gneisses,  long  since  referred  by  me  to  the  Montalban 
series,*  and  by  Brooks  placed  above  the  iron-bearing  beds 
of  the  Menominee  district,  have  since  1880  been  found  by 
Rominger  to  be  an  older  and  underlying  series,  occurring 

«  Azoic  Bocks,  pp.  223-225. 


XI.] 


LOWER  TACONIC   U0CK8. 


681 


a  Quartzite 
)iH)re  group, 
ppear  cli)sely 
As  of  quivvtz- 
ntevstratitiecl 
ith  grapliitic, 
iper,  of  Ueiuii- 
iiatetl,  aiKl,  in 
he  limestones 
division,  gveat 
nes  with  mica 
ey  are  reddish, 
,r  to  be  in  two 
i  body  of  Ume- 
of  tlie  Gogebic 
r  those  of  Mar- 
hose  of  Vevmil- 
ical.    Theargil- 
in  the  St.  Louis 
ire  by  Rominger 
urouBay.    The 
IS  described  by 
,  very  lil^e  that  of 
Rominger  there 
•oup ;  but,  to  the 
and  by  Irving  as 
^.    This,  as  seen 
i  it  is  apparently 
•haracters  of   the 
n  New  York  and 

limes    with    gray 

;o  the  Montalban 

p  iron-bearing  beds 

880  been  found  by 

,g  series,  occurring 


in  that  area,  wliich  is  there  brought  to  overlie  the  iron- 
bearing  sc'iists  by  a  fohl  in  the  stratification.  It  would 
a[)i)t'ar  from  all  these  fau's  that,  while  the  dioritic  and  ser- 
pentine grou[)  of  Rominger  is  the  true  Iluronian,  the 
great  series  of  (piartzites,  marbles,  argillites,  and  iron- 
bearing  strata  of  tlieso  regions,  —  the  so-called  Animikie 
group,  —  are  wholly  distinct  therefrom,  and,  as  long  sinco 
declared  by  IIought(»n  and  Emmons,  are  Taconian. 

§  91.  [The  fact  that  the  Taconian  or  Animikie  series  in 
northern  Michigan  rests  sonietimes  upon  the  granitoid  or 
gneissic  group,  sometimes  ui)on  the  dioritic  group  of  Ro- 
minger, and  elsewhere  upon  a  mica-schist  series  having  the 
characters  of  the  Montalban,  goes  far  to  show  its  strati- 
graphical  distinctness  from  all  three  of  these.  Its  separa- 
tion from  the  dioritic  group  was  early  noticed  by  Logan, 
when  he  described  the  unconformable  superposition  of  tiiis 
series  (the  lower  division  of  his  Upper  Copper-bearing 
series)  on  the  ancient  greenstone  (Huronian)  series,  and 
the  presence  of  i)ortions  of  this  in  the  basal  conglomerates 
of  the  latter.  There  are,  however,  as  I  have  elsewhere 
noticed,*  certain  mineralogical  resemblances  between  the 
Taconian  and  the  softer  and  more  schistose  beds  of  the 
Huronian,  with  which  they  were  confounded  by  Murray 
at  more  than  one  locality  along  the  north  shore  of  Laka 
Superior.  Hence,  after  visiting  the  Marquette  district  in 
1861,  he  did  not  hesitate  to  call  the  Iron-bearing  series  of 
that  region  Huronian ;  a  designation  adopted  by  the  geo- 
logical survey  of  Canada.  In  this  he  was  followed  by 
J.  P.  Kimball  in  his  study  of  the  Marquette  iron-ores  in 
1865,  by  Hermann  Credner  in  1869,  by  T.  B.  Brooks  in 
1873,  and  again  by  Irving  in  1883.  All  of  these  include 
the  two  series  under  the  common  name  of  Huronian,  and 
the  estimates  of  the  thickness  of  the  Huronian  have  bern 
based  upon  that  of  the  two  united.  The  distinctness  of 
the  underlying  dioritic  group  with  its  serpentines  and 
chloritic  rocks,  which  together  constitute  the  Huronian  or 

«  Azoic  Bocks,  p.  202. 


.    ,.    i 

'    '      \ 

<■-('  ,  1 

t                 1      > 

■  ',1 

J,      • 

m 

Ilk?) 

,  j> 


m 


I'M 


582 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[ZI. 


pietre  verdi  —  alike  from  the  older  granitoid  and  gneissic 
group,  from  the  mica-schist  or  Montalban  group,  and  from 
the  great  overlying  Animikie  or  Taconian  system,  includ- 
ing the  quartzites,  marbles,  iron-ores  and  argillites,  is 
however  manifest.  The  succession  is  thus  brought  into 
complete  accordance  with  that  which  is  found  in  many 
parts  of  the  Appalachians,  as  well  as  in  southern  Europe, 
as  pointed  out  in  part  iv.  of  Essay  X.] 

§  92.  Considering  the  pre-Cambrian  age  of  the  Lower 
Taconic  of  Emmons  to  be  established,  as  well  as  its  dis- 
tinctness alike  from  the  older  crystalline  rocks  below  and 
from  the  Cambrian  series  above,  to  which  Emmons  had 
given  the  name  of  Upper  Taconic  —  it  was  proposed  by 
the  writer,  in  1878,  to  restrict  the  term  of  Taconic,  —  for 
which  the  alternative  name  of  Taconian  was  then  sug- 
gested, —  to  the  Lower  Taconic  of  Emmons.* 

The  question  as  to  whether  the  Cambrian  is  to  be 
regarded  as  the  base  of  the  paleozoic  series,  or,  in  other 
words,  whether  the  Taconian  should  be  considered  as 
belonging  to  eozoic  or  paleozoic  time,  was  discussed  by 
the  author,  in  1876,  when  he  wrote  as  follows :  "  It  will 
be  found  as  difficult  to  draw  the  line  between  the 
eozoic  and  paleozoic  as  it  is  to  define  that  between  the 
mesozoic  and  paleozoic  on  the  one  hand,  or  between 
the  mesozoic  and  cenozoic  on  the  other.  There  are  no 
hard-and-fast  lines  in  nature ;  breaks  are  local,  and  there 
is  nowhere  an  apparent  hiatus  in  the  geological  succes- 
sion which  is  not  somewhere  filled."  Referring  to  the 
Lingula  found  by  Prime  in  the  Auroral  limestone  of  Penn- 
sylvania, it  was  said:  "This  seemingly  imperishable 
type  of  brachiopods  may  serve,  like  the  rhizopods,  repre- 
sented by  Eozoon,  as  a  connecting  link  between  eozoic 
and  paleozoic    time."  f     Subsequently,  in  a  paper  read 

*  On  the  Geology  of  the  Eozoic  Rocks  of  North  America  ;  Proc.  Bost. 
Soc.  Nat.  Hist.,  xix.,  278  ;  and  Azoic  Rocks,  p,  207. 

t  Proc.  Amer.  Assoc.  Adv.  Science,  1876,  pp.  207-208 ;  also.  Azoic 
Rocks,  p.  211. 


XI.] 


UPPER  TACONIO  P.OCKS. 


583 


before  the  National  Academy  of  Sciences  in  April,  1880,* 
it  was  said  of  the  Taconian  series:  "These  older  rocks 
are  not  without  traces  of  organic  life,  having  yielded  in 
the  Appalachian  valley  the  original  Scolithus,  and  related 
markings,  besides  obscure  brachiopods;  and  in  Ontario, 
besides  similar  Scolithus-like  markings,  a  form  apparently 
identical  with  the  Eozoon  of  the  more  ancient  gneisses. 
We  may  hope  to  find  in  the  Taconian  series  a  fauna 
which  shall  help  to  fill  the  wide  interval  that  now  divides 
that  of  the  eozoic  rocks  from  the  Cambrian.  We  should 
seek,  in  the  study  of  stratigraphical  geology,  not  the 
breaks  dividing  groups  from  each  other,  so  much  as  the 
beds  of  passage  which  serve  to  unite  all  these  groups  in 
one  great  system." 


i 


Pil 


1  America  ;  Proc.  Bost. 

n.  ,   . 

).  207-208;  also,  Azoic 


V. — THE   UPPER  TACONIC   OR  FIRST  GRATWACKE. 

§  93.  We  now  return  to  the  history  of  the  First  Gray- 
wacke,  which,  as  has  been  shown,  was  by  Mather,  in  1842, 
assigned,  contrary  to  Eaton's  conclusion,  to  a  horizon 
above  the  Trenton  limestone,  and  to  the  position  of  the 
Second  Graywacke  of  the  latter.  Mather  regarded  the 
Taconic  quartzite,  limestone,  and  slates  of  Emmons  as 
forming  one  continuous  series  with  the  succeeding  First 
Graywacke  of  Eaton,  and  referred  the  whole  succession  to 
the  various  subdivisions  of  the  New  York  system  from 
the  Potsdam  to  the  Medina,  both  included. 

[Emmons,  in  his  report  on  the  Northern  district  of  New 
York,  in  1842,  approached  the  discussion  of  this  question 
with  the  remark  that  although  the  Taconic  rocks  do  not 
appear  within  that  district,  a  knowledge  of  them  is  requi- 
site to  a  correct  understanding  of  the  relations  of  the 
Champlain  division.  While  maintaining  that  the  Quartz- 
ite, Limestone,  and  Argillite  (which  Eaton  had  placed 
beneath  the  First  Graywacke)  were  inferior  to  the  Tren- 
ton limestone,  and,  indeed,  to  the  whole  New  York 
system,  Emmons  therein  showed  a  divided  opinion  as 
*  Canadian  Naturalist  for  1880,  vol.  iz.,  p.  430. 


/  ■ 


I. 


I' 


ii 


ill 


i 


,m 


i«yiaaa8»i|Miih<r^:frt»>»-<tt.»,aadi^t.  a«i<  'i~.!< ' 


684 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


il 


to  the  horizon  of  the  Graywacke  itself.  In  those  chapters 
of  the  report  in  which  he  describes  the  Taconic  system, 
he  accepts  the  view  of  Eaton  that  it  follows  immediately 
the  Argillite  ;  while  in  the  chapter  on  the  New  York 
Transition  system,  he  adopts  the  notion  of  Mather  that 
it  is  identical  with  the  Second  Graywacke,  and  above  the 
Trenton  —  the  Lower  Secondary  limestone  of  Eaton. 
These  contradictions,  which  I  have  already  elsewhere 
signalized,*  have  perplexed  students,  and  demand  farther 
notice.  In  describing  the  rocks  of  the  Champlain  divis- 
ion, in  that  volume  (page  121),  we  are  told  by  Emmons 
that  a  belt  of  red  and  purple  slates  v  ith  red  sandstones, 
regarded  as  belonging  to  the  Pni'^'^ki  or  Loraine  shales, 
extends  "  through  the  higher  parts  of  Columbia,  Rensse- 
laer, and  Washington  Counties,"  in  New  York,  "and 
onward  through  Vermont  into  Canada."  Again  we  are 
informed  (pages  280-282)  that  shales  and  sandstones 
belonging  to  the  horizon  of  the  Loraine  subdivision  and 
the  succeeding  Gray  sandstone,  and  seen  in  Addison  and 
Charlotte,  Vermont,  belong  to  this  belt,  extending  from 
Columbia  County,  New  York,  to  the  Canada  line.  They 
are  farther  said  to  be  represented  by  the  sandstones  of 
Burlington  and  Colchester,  Vermont,  and  by  the  sand- 
stones in  the  fortifications  of  the  city  of  Quebec  (pages 
124, 125). 

§  93  A.  [When,  however,  he  comes  to  describe  the 
rocks  of  the  Taconic  system  in  this  same  report,  he 
declares  that  these  rocks  also  extend  through  the  eastern 
counties  of  New  York  from  the  Highlands,  beyond  which 
"  they  are  found  stretching  through  the  whole  length  of 
Vermont,  and  into  Canada  as  far  as  Quebec  "  (page  136). 
This  description  in  1842  obviously  applies  only  to  the 
portion  of  the  Taconic  system  afterwards  distinguished 
by  Emmons  as  Upper  Taconic,  since,  it  is  known,  the  char- 
acteristic Quartzite,  the  Stockbridge  limestone,  and  the 
Magnesian  slates  of  the  Lower  Taconic,  are  not  recognized 

*  Aaoic  Bocks,  p.  57. 


i 


GY.  ''**• 

those  chapters 
iconic  system, 
3  immediately 
[le  New  York 
f  Mather  that 
and  above  the 
ne    of    Eaton, 
ady   elsewhere 
lemand  farther 
aamplain  divis- 
Id  by  Emmons 
red  sandstones, 
Loraine  shales, 
lumbia,  Rensse- 
;w  York,   "and 
Again  we  are 

and  sandstones 
subdivision  and 
in  Addison  and 

extending  from 
ada  line.      They 
lie  sandstones  of 
nd  by  the  saud- 
f  Quebec  (pages 

,  to  describe  the 
same  report,  he 
ough  the  eastern 
idsrbeyond  which 
e  whole  length  of 
jbec  "  (page  136). 
.plies  only  to  the 
ards  distinguished 
s  known,  the  char- 
imestone,  and  the 
are  not  recognized 


XI.] 


UPPER  TACONIC   ROCKS. 


585 


anywhere  along  the  line  mentioned,  northward  of  central 
Vermont.  On  the  contrary,  the  typical  Upper  Taconic  is 
traced  throughout  the  whole  distance  to  the  city  of  Que- 
bec, where  the  well  known  sections  of  it  were  by  the 
geological  survey  of  Canada  described  as  belonging  to 
the  horizon  of  the  Second  Graywacke,  until  1861,  when 
there  were  referred  by  Logan  to  the  First  Graywacke  or 
Upper  Taconic,  with  the  local  name  of  the  Quebec  group. 

[That  the  Taconic  system  as  set  forth  in  1842  included 
the  Upper  Taconic  or  First  Graywacke,  is  farther  shown 
by  the  detailed  descriptions  of  Emmons  in  chapter  v.  of  his 
report  of  that  year.  He  there  includes  besides  the  Granu- 
lar Quartz-rock,  the  Stockbridge  limestone,  and  the  Mag- 
nesian  slate,  two  otlier  divisions,  the  "  Sparry  limestone, 
generally  known  as  the  Sparry  Lime-rock,"  of  Eaton,  and 
the  "  Taconic  slate."  With  regard  to  the  latter  limestone, 
he  remarks  that  it  is  "  quite  even  bedded,  of  a  gray 
color,  very  sparry,  and  is  underlaid  by  a  line  argillaceous 
slate."  He  adds  that  tlie  Stockbridge  limestone,  "being 
often  sparry,  and  of  a  fine  texture,  is  mistaken  for  the  true 
Sparry  'mestone."  The  Taconic  slate  is  more  or  less  inter- 
stratifieu  with  limestone,  and  "often  becomes  a  coarse 
graywacke."  This  Taconic  slate  belt  was,  according  to 
him,  distinct  from  the  Magnesian  slate,  and  had  then 
been  traced  150  or  200  miles  north  and  south,  without 
variation  in  characters. 

§  98  B.  [The  true  succession  of  these  divisions,  or  "the 
order  in  which  the  Taconic  rocks  lie,  being  unsettled,  or, 
at  least,  not  being  as  clearly  established  as  is  desirable  " 
(page  150),  Emmons  tell  us  that  in  his  descriptions  he 
follows  the  geographic  order,  beginning  with  the  most 
western  mass  of  slate,  the  Taconic  slate,  succeeding  which 
was  the  Sparry  limestone.  The  question  of  the  strati- 
graphical  sequence  was  complicated  by  faults,  with  up- 
throws of  the  strata  on  the  eastern  side,  the  significance 
of  which  Emmons  points  out  in  1846,  as  well  as  by  the 
break  at  the  base  of  the  Graywacke  noticed  by  Eaton  (^ante^ 


It 


54; 


586 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


'ji 


page  626).  He,  however,  informs  us,  in  1842,  that  the 
Taconic  shite  lies  between  the  so-called  Hudson-River  or 
Loraine  rocks  on  the  west,  and  the  Sparry  limestone  on 
the  east,  and,  moreover,  that "  it  is  undoubtedly  overlapped 
by  the  former  rocks,  and  passes  beneath  the  latter  with  a 
dip  of  30°  or  35° "  (page  150).  In  1846  Emmons  gave  us 
farther  details  with  regard  to  those  same  Taconic  slates, 
the  limits  of  which,  in  the  typical  sections,  he  had  already 
defined  in  1842.  He  now  tells  us  that  "  the  Taconic  slate, 
with  its  subordinate  beds,  occupies  almost  the  whole  of 
Columbia,  Rensselaer,  and  Washington  Counties,"  and  is 
of  immense  tliickness.  He  notes  a  section  from  Lansing- 
burgh  to  the  Sparry  limestone  on  the  east,  as  having  a 
breadth  of  at  least  twenty  miles,  and,  while  conjecturing 
repetitions,  still  supposes  that  its  volume  "  exceeds  that 
of  all  the  members  of  the  New  York  system  put  together." 
He  describes  as  subordinate  divisions  of  this  slate  group, 
a  black  slate,  with  trilobites,  and  other  slates  with  impres- 
sions resembling  graptolites,  *  having  already  in  1842  de- 
clared that  of  these,  his  Taconic  rocks,  the  upper  portion 
is  "  the  lower  part  of  the  Silurian  system."  f 

§  93  C.  [That  this  great  and  continuous  belt  of  slates 
with  sandstones  and  interbedded  limestones,  overlaid  by 
the  Second  Graywacke,  and,  together  with  the  Sparry 
limestone,  occupying  the  whole  breadth  between  it  and 
the  other  three  named  members  of  the  Taconic  system, 
belongs  to  the  First  Graywacke  or  Upper  Taconic,  as 
defined  by  Eaton  (^ante,  p.  520),  is  too  evident  to  require 
discussion.  It  may  farther  be  said  that  notwithstanding 
the  uncertainty  as  to  sequence  of  these  various  members 
expressed  by  Emmons,  the  position  of  the  Sparry  lime- 
stone had  been  clearly  and  correctly  fixed  by  Eaton,  ten 
years  before,  when  he  placed  it  at  the  summit  of  the 
First  Graywacke,  and  included  it  in  the  Lower  Secondary 


m 


'  I' 


•  Agriculture  of  New  York,  pp.  65-72. 

t  Geology  of  Ncrthem  District  of  New  York,  p.  163. 

160, 161. 


See  also  post, 


1(1 


)GY. 


IXI. 


.842,  tliat  the 
.ason-River  or 
limestone  on 
(lly  overlapped 
e  latter  with  a 
mmons  gave  ns 
Taconic  slates, 
he  had  already 
e  Taconic  slate, 
it  the  whole  of 
ounties,"  and  is 
a  from  Lansing- 
sast,  as  having  a 
lile  conjecturing 
e  "exceeds  that 
m  put  together." 
this  slate  group, 
ates  with  impres- 
;ready  ui  1842  de- 
the  upper  portion 

ous  belt  of  slates 
tones,  overlaid  by 
with  the  Sparry 
ill  between  it  and 
e  Taconic  system, 
Jpper  Taconic,  as 
evident  to  require 
at  notwithstanding 
e  various  members 
,  the  Sparry  Ume- 
ixed  by  Eaton,  ten 
the  summit  of  the 
le  Lower  Secondary 

J,  p.  163.     See  also  post, 


XL] 


UPPER  TACONIC   ROCKS. 


687 


limestones,  as  the  stratigraphical  equivalent  of  the  Calci- 
ferous  Sand-rock  and  the  Trenton  limestone  of  the  west 
side  of  Lake  Champlain  (^ante,  p.  520).  James  Hall,  who 
in  1857  still  held  the  view  of  Mather  that  this  graywacke 
was  no  other  than  the  Second  Graywacke  of  Eaton,  then 
wrote  of  "  that  part  of  the  Hudson-River  group  which  is 
sometimes  designated  as  Eaton's  Sparry  limestone, — being 
near  the  summit  of  the  gr.  'ip."  * 

§  94.  [  In  the  report  on  the  Agriculture  of  New  York, 
in  1846,  just  cited,  in  which  Emmons  gives  us  in  much 
detail  his  more  matured  conclusions  on  the  Taconic 
system,  he  abandons  the  view  of  Mather  as  to  the  age  of 
the  Graywacke  series  which  found  a  place  in  certain  chap- 
ters of  his  report  of  1842,  already  quoted,  and  holds  to 
that  laid  down  in  chapters  vii.,  viii.,  and  ix.,  of  that 
report.  The  complete  discordance  of  these  with  the 
other  portions  of  the  volume,  and  their  agreement  with 
the  report  of  1846,  show  them  to  have  been  written  at  a 
later  neriod  than  the  rest,  and  interpolated  therein.  The 
great  belt  of  slates,  limestones,  and  graywacke  designated 
the  Taconic  slates,  and  extending  from  the  valley  of  the 
Hudson  through  Vermont  into  Canada  as  far  as  Quebec, 
was  now  regarded  as  the  lower  part  of  the  Champlain 
division,  and  as  a  thickened  and  modified  form  of  the 
Calciferous  Sand-rock ;  which,  in  its  eastward  extension, 
was  said  to  include  a  great  variety  of  rocks,  and  to  be 
"protean"  in  its  characters.  The  Potsdam  sandstone 
was  then  supposed  by  Emmons  to  be  wanting  in  this 
eastern  region,  but  he  was  afterwards  led  to  regard  cer- 
tain strata  in  western  Vermont  as  its  representative. 
Eaton's  three  divisions  of  Quartzite,  Limestone,  and 
Argillite  underlying  this  First  Graywacke  series,  and  con- 
stituting the  lower  part  of  the  Taconic  system,  were  still 
held  by  Emmons  to  be  older  than  the  base  of  the  Cham- 
plain division.  The  stratigraphical  discordance  between 
the  Argillite  and  the  Graywacke,  long  before  noticed 
♦  Report  Geol.  Survey  of  C&nada,  1857,  p.  117. 


m 


mi^ 


im':: 


688 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


If 


by  Eaton,  was,  however,  apparently  disregarded  by  Em- 
mons.] 

§  95.  In  1855,  returning  to  the  subject  in  his  treatise 
entitled  "  American  Geology,"  Emmons,  while  still  adher- 
ing to  the  views  of  its  age  and  relations  announced  by  him 
in  1846,  proposed  to  consider  the  Taconic  system  as  con- 
sisting of  two  parts,  between  which,  according  to  him, 
"  the  line  of  demarcation  is  tolerably  well  defined."  Of 
the^e,  the  lower  division,  or  Lower  Taconic,  included  the 
thres  lower  members  just  mentioned,  and  the  upper  divis- 
ion, or  Upper  Taconic,  the  First  Graywacke,  or  the  great 
group  of  so-called  Taconic  slates,  with  the  Sparry  lime- 
stone. The  same  v'hiw  is  farther  set  forth  in  his  "  Manual 
of  Geology,"  in  1860,  and  in  his  subsequent  reports  on 
the  geology  of  North  Carolina. 

§  96.  We  hfive  now  to  consider  more  at  length  the 
history  of  the  First  Graywacke  belt  of  Eaton,  which,  by 
his  observations,  and  those  of  Emmons  and  Mather,  was 
traced  from  below  Quebec,  on  the  St.  Lawrence,  southward 
through  Vermont,  and  along  the  east  side  of  the  valley 
of  the  Hudson.  Mather,  who  supposed  this  belt  to  be 
represented  farther  south,  along  the  west  side  of  the 
Hudson,  by  the  Shawangunk  range  (a  prolongation  of  the 
Kittatinny  Mountain  of  New  Jersey  and  Pennsylvania, 
which  is  of  Oneida-Medina  age,  and  consequently  belongs 
to  the  Second  Graywacke),  referred  the  whole  belt  north 
and  east  of  the  Hudson  to  this  period.  In  the  opinion  of 
Emmons,  however,  thp  First  Graywacke,  to  the  west  and 
south  of  the  Hudson,  v/as  represented,  not  by  the  Shawan- 
gunk, but  by  a  parallel  range  a  little  to  the  eastward,  to 
be  mentioned  below  (§  98).  This  Upper  Taconic  belt, 
according  to  him,  is  continued  southwestward,  with  some 
interruptions,  across  New  Jersey  and  Pennsylvania,  into 
the  valley  of  Virginia ;  where,  near  Wytheville,  and  again 
near  Abingdon,  he  described  sections  of  the  Upper  Taconic 
resting  upon  Lower  Taconic  rocks. 

§  97.   We  have  not,  however,  as  far  as  I  am  aware. 


)GY. 


tXI. 


XI.] 


UPPER   TACONIC   ROCKS. 


589 


arded  by  Ein- 

in  his  treatise 
hile  still  adber- 
lounced  by  bim 
system  as  con- 
■ording  to  bim, 
1  defined."     Of 
ic,  included  tbe 
tbe  upper  divis- 
ke,  or  the  great 
be  Sparry  Ume- 
i  in  his  "  Manual 
^uent  reports  on 

re  at  length  the 
Eaton,  which,  by 
and  Mather,  was 
n-ence,  southward 
liele  of  the  valley 

this  belt  to  be 
west  side  of  the 
.rolongation  of  the 
md  Pennsylvania, 
isequently  belongs 
,e  whole  belt  north 

In  the  opinion  of 
ce,  to  the  west  and 
not  by  the  Shawan- 
to  the  eastward,  to 
pper  Taconic  belt, 
estward,  with  some 

Pennsylvania,  into 
ytheville,  and  again 
f  the  Upper  Taconic 

far  as  I  am  aware. 


any  detailed  account  of  these  Upper  Taconic  rocks  in  the 
great  valley  from  Virginia  to  the  region  east  of  the  Hud- 
son. In  Pennsylvania  they  have  received  little  notice 
from  the  two  geological  surveys  of  that  State,  though 
they  are,  as  I  have  already  stated,  largely  developed  in 
the  great  valley  in  the  interval  between  the  Delaware 
and  the  Susquehanna  Rivers  (  §  30).  Tliey  were  here 
included  by  H.  D.  Rogers  in  the  IMatinal  series,  and 
placed  by  him  below  the  Levant  sandstone.  He,  at  the 
same  time,  noticed  their  resemblance  to  the  beds  immedi- 
ately aboVe  this  sandstone ;  a  likeness  which  led  Mather 
to  refer  them,  in  eastern  New  York,  to  tliis  higher  hori- 
zon. It  will  be  remembered  that  the  roofing-slates  of  the 
Delaware,  which  succeed  the  Aurora)  limestones,  and  are 
supposed  to  be  included  in  the  Lower  Taconic  of 
Emmons,  are  assigned,  botli  by  Rogers  and  by  Chance, 
to  a  position  near  the  base  of  the  series  of  about  6000 
feet  of  so-called  Matinal  rocks  (§  29).  This  grcivt  series 
in  Pennsylvania  has  thus  the  stratigrapliical  positic.i,  as 
well  as  the  characters,  of  the  Upper  Taconic  or  First 
Graywacke,  which  is  so  conspicuous,  both  to  the  north- 
east and  the  southwest,  along  the  Appalachian  valley. 

§  98.  The  question  now  arises  to  what  extent  the 
rocks  of  tliis  series  are  found  to  the  eastward  of  the  great 
valley;  that  is  to  say,  east  of  the  Blue  Ridge,  the  South 
Mountain,  and  its  northern  prolongation  from  the  High- 
lands of  the  Hudson  into  New  England  and  Canada. 
So  far  as  known,  there  is  nothing  to  represent  the 
Upper  Taconic  in  this  eastern  area,  farther  north  than 
the  Highlands.  Resting  upon  the  ancient  gneiss  of  the 
Highlands  in  Orange  County,  New  York,  there  is,  how- 
ever, a  range  of  rocks,  formerly  designated  as  graywacke, 
which  were  by  Mather  described  as  a  parallel  belt  lying 
to  the  southeast  of  Shawangunk  jNIountain,  of  which  he 
regarded  it  as  a  repetition.  This  graywacke-belt  was 
said  by  Horton  to  constitute,  in  parts  of  Orange  County, 
two  or  more  narrow  bands,  the  strata  of  which  dip  east- 


ffelT 


:W^: 


590 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


ts. 


\\  r- 


ward  at  high  angles,  and  lie  directly  upon  the  ancient 
gneiss,  beneath  which,  in  some  cases,  they  seem  to  pass. 
The  continuation  of  this  belt  in  New  Jersey  is  known  as 
the  Green-Pond  Mourtain  range.  This,  while  regarded 
by  Mather  as  belonging  to  the  Second  Graywacke,  was 
by  Rogers  conjectured  to  be  an  outlier  of  the  great  meso- 
zoic  area  which  lies  farther  to  the  southeast,  but  by 
Emmons  was  supposed  to  belong  to  the  First  Graywacke. 
More  recently,  it  has  been,  by  Professor  Cook,  in  his  geo- 
logical survey  of  New  Jersey,  described  as  belonging  to  a 
still  lower  horizon,  and,  under  the  name  of  Potsdam, 
referred  to  the  base  of  the  Primal  of  Rogers.  The  litho- 
logical  characters  of  this  graywacke-belt,  as  I  have 
observed  it  in  New  Jersey,  are,  however,  very  distinct 
from  those  of  the  Primal.  This  latter  in  the  adjacent 
region  of  northeastern  Pennsylvania,  along  the  same 
gneissic  belt,  is,  where  it  appears  from  beneath  the  Auroral, 
represented  only  by  a  small  volume  of  quartzite,  with 
soft  schists  :  a  development  wholly  unlike  the  Green-Pond 
Mountain  conglomerate. 

§  99.  The  relations  of  this  graywacke-belt  to  the  Auro- 
ral limestone,  often  found  adjacent,  as  well  as  to  other 
and  fossiliferous  limestones  and  shales  met  with  along  the 
range,  both  in  New  Jersey  and  in  Orange  County,  New 
York,  are  complicated  by  many  stratigraphical  acci- 
dents, and  demand  further  investigation.*  A  summary 
of  the  facts  regarding  it,  as  gathered  from  the  reports 
of  Mather  and  of  Horton,  is  given  in  the  author's  "  Azoic 
Rocks,"  pages  35-37 ;  while,  for  later  observations  by 
Cook,  in  New  Jersey,  the  reader  is  referred  to  his  vol- 
ume on   the   geology  of  that  State,  published  in   1868, 

*  An  area  of  fossiliferous  argillites,  found  In  the  Peach-Bottom  dis- 
trict in  Lancaster  County,  Pennsylvania,  some  distance  to  the  southeast 
of  the  second  Taconian  belt,  and  on  the  Susquehanna  River,  along  the 
borders  of  Maryland,  is  perhaps  to  bs  regarded  as  an  outlier  belonging  to 
the  First  Graywacke  ;  since  it  has  lately  furnished  to  Dr.  Persifor  Frazor 
graptolites  referred  by  Professor  Hall  to  that  horizon.  I  am  indebted  <  o 
Dr.  Frazer  for  these  facts,  the  results  of  Professor  Hall's  observations  not 
being  as  yet  published. 


,OGY.  ^^ 

m  the   ancient 
•  seem  to  pass, 
ley  is  known  as 
while  regarded 
Tiaywacke,  was 
the  great  meso- 
itheast,  but  by 
irst  Graywacke. 
:5ook,  in  his  geo- 
s  belonging  to  a 
tne  of  Potsdam, 
rers.    The  litho- 
jelt,   as    I    have 
er,  very  distinct 
in  the  adjacent 
along  the    same 
leath  the  Auroral, 
)f   qiiartzite,  with 
e  the  Green-Pond 

i-belt  to  the  Auro- 
well  as  to  other 
let  with  along  the 
tnge  County,  New 
•atigraphical    acci- 
on.*     A  summary 
from  the  reports 
he  author's  "  Azoic 
jr  observations  by 
■eferied  to  his  vol- 
mblished  in  1868, 

I  the  Peach-Bottom  dis- 
iistance  to  the  southeast 
ehanna  River,  along  the 
3  an  outlier  belonging  to 
iedtoDr.PersiforFrazor 
,rizon.  I  am  indebted  10 
)r  Hall's  observations  not 


XI.] 


UPPER  TACONIC  ROCKS. 


691 


already  cited,  in  §  80.  In  Bearfort  Mountain,  in  this 
region,  according  to  Cook,  the  conglomerate  beds  are 
overlaid  by  slates,  which  are  followed  by  sandstones, 
called  Oneida  and  Medina,  while  at  Upper  Longwood, 
fossiliferous  limestone,  regarded  as  Trenton,  overlies  the 
red  slates  of  the  conglomerate  belt  (loc.  cit.,  pp.  149,  83). 

[Later  studies  throw  farther  light  upon  the  rocks  of  this 
belt.  Thus  Smock,  in  1884,  discovered  in  certain  flagstones 
of  the  series  remains  of  Devonian  plants,  while  it  has 
been  found  by  Darton  tliat  the  fossiliferous  limestones  at 
Upper  Longwood,  and  near  Newfoundland,  in  New  Jersey, 
are  not  Trenton,  as  hitiierto  supposed,  but  approximately 
Niagara  in  age.  Dwight,  moreover,  has  found  that  the 
sandstones  at  the  Townsend  iron-mine,  near  Cornwall,  in 
Orange  County,  New  York,  are  of  Oneida-Medina  age, 
and  are  overlaid  by  Lower  Helderberg  limestones,  the 
fauna  of  which  has  been  described  in  detail  by  Darton.* 
The  recent  observations  of  the  latter,  in  part  unpublished, 
also  show  within  the  limits  of  this  area  the  existence  of 
strata  holding  Loraine,  Trenton,  and  Calciferous  forms, 
which,  however,  according  to  him,  appear  to  be  associated 
with  a  series  of  older  schists  and  limestones,  without 
observed  fossils.  While  there  is  thus  paleontological  evi- 
dence in  confirmation  of  the  view  of  Mather  tliat  this  belt 
includes  the  rocks  of  the  Second  Graywacke,  it  would 
also  appear  to  embrace  strata  of  lower  horizons,  as  sup- 
posed by  Emmons  and  by  Cook.  According  to  Darton, 
who  is  now  engaged  in  the  study  of  this  region,  and  to 
whom  I  am  indebted  for  these  un])ublished  details,  the 
structure  is  complicated  by  a  considerable  fault,  tdong 
the  west  side  of  which  the  newer  rocks  predominate.] 

§  100.  Passing  now  to  the  consideration  of  the  Upper 
Taconic  rocks  in  the  regions  north  of  the  Highlands  of 
the  Hudson,  where  they  have  been  chiefly  studied,  we 

*  Dwight,  Trans.  Vassar  Bros.  Institute,  ii.,  1883-84,  p.  75 ;  Smock, 
Report  on  Geology  of  New  Jersey,  1884,  p.  35,  and  Darton,  Anmr.  Jour. 
Science,  1885,  xxix.,  p.  432,  and  1886,  xxx.,  p.  209. 


jill 
p 


r 


i'; 


,'i:l,l  " 


692 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XL 


remark,  in  the  first  place,  ^hat  here,  as  farther  south,  they 
are  found  resting  alike  ujion  tlie  Lower  Taconic  and  the 
older  crystalline  rocks  which  appear  on  the  western  hor- 
der  of  the  latter.  The  base  of  the  Upper  Taconic,  as 
described  by  Emmons,  here  consists  of  coarse  greenish 
sandstones,  with  shales  and  conglomerates,  holding  mate- 
rials derived  from  the  underlying  crystalline  rocks.  The 
higher  part  of  the  series  was  said  to  be  very  variable 
in  character,  including  olive-colored  sandstones,  and  so- 
called  "brown-weathering  calcareous  sandstones,"  which 
are  really  arenaceous  dolomites  holding  much  carbon- 
ate of  iron,  beds  of  quartzite  with  green,  purple,  and  red 
roofing-slates,  followed  by  blue  limestones,  —  the  Sparry 
lime-rock  of  Eaton ;  while  towards  the  summit  are 
black  shaly  limestones,  the  series  terminating  with  a 
black  slate.  The  upper  part  of  this  series  was  declared 
to  be  fossiliferous,  containing  remains  of  graptolites, 
fucoids,  and  trilobites.  In  a  section  from  near  Comstock's 
Landing,  eastward  to  Middle  Granville,  in  Washington 
County,  New  York,  in  .which  the  above-described  rooks 
are  found,  there  is,  Emmons  tells  us,  no  representative  of 
the  granular  quartzites,  the  limestones,  the  talcose  slates, 
or  the  characteristic  roofing-slates  of  the  Lower  Taconic. 
The  rocks  in  this  section  have,  according  to  Emmons,  an 
apparent  thickness  of  not  less  than  25,000  feet ;  a  volume 
probably  due  to  repetitions  from  numerous  parallel  dislo- 
cations, with  upthrows  on  the  east  side ;  as  a  result  of 
which  the  succession  already  described  is  apparently 
inverted,  so  that  the  black  slates  of  the  western  part  of 
the  section  seem  to  pass  beneath  all  the  other  members, 
and  the  green  sandstones  of  the  eastern  part  appear  to 
overlie  them  all. 

§  101.  This  condition  of  things,  so  far  from  being  ex- 
ceptional, is  very  frequent  along  the  eastern  base  of  the 
Atlantic  belt,  from  the  Gulf  of  St.  Lawrence  to  Alabama, 
and  is  apparently  general  in  similar  disturbed  regions. 
Emmons  has  described  this  with  detail,  and  noted  the 


)QY.  ^'*''- 

ler  south,  they 
iconic  and  the 
e  western  bor- 
,er  Taconic,  as 
joavse  greenish 
,  hokling  mate- 
ne  rocks.     The 
e  very  variable 
[stones,  and  so- 
Jstones,"  which 
;   much   carbon- 
\  purple,  and  red 
es,  — the  Sparry 
he    summit    are 
ninating  with  a 
.•ies  was  declared 
5   of    graptolites, 
near  Comstock's 
3,  in  Washuigtuu 
e-described  rocks 
representative  of 
the  talcose  shites, 
Lower  Taconic. 
g  to  Emmons,  an 
00  feet ;  a  volume 
ous  parallel  dislo- 
ie ;  as  a  result  oi 
,ed    is   apparently 
le  western  part  of 
le  other  members, 
,rn  part  appear  to 

far  from  being  ex- 

^astern  base  of  the 

^rence  to  Alabama, 

disturbed  regions. 

Ill,  and  noted  the 


XI.J 


UPPER   TACONIC   HOCKS. 


iU3 


parallel  uplifts,  increasing  in  vertical  extent  as  we 
api)n)ach  the  mountain-chain  of  okler  rocks.  I  have 
discussed  this  matter,  with  many  illustrations,  in  my 
volume  on  ''Azoic  Rocks,"  pages  54,55.  It  is  tiiere 
shown  that  along  the  whole  eastern  side  of  the  great 
Appalachian  valley  the  newer  rocks  are  found  dipping  to 
the  eastward,  towards  the  older  rocks,  and  sometimes 
even  beneath  them.  Thus,  the  Cambrian  Graywacke 
appears  to  pass  beneath  the  crystalline  rocks  of  the  High- 
lands of  the  Hudson  and  of  the  island  of  Newfoundland; 
the  Ordovician  beds  benea<-\  this  First  Graywacke ;  and 
farther  southward,  in  Virginia,  the  carboniferous  rocks 
beneath  the  older  paleozoic.  These  relations  result  from 
dislocations,  with  uplifts  on  the  eastern  side,  often  con- 
nected with  inverted  folds. 

§  102.  While  the  green  sandstones  in  New  England, 
according  to  Emmons,  constitute,  along  its  eastern  border, 
the  base  of  the  series,  thei'e  appears  farther  west  in  the 
valley,  along  the  eastern  shore  of  Lake  Champlain, 
another  mass  of  strata,  the  so-called  Red  Sand-rock  of 
Vermont,  which,  towards  the  sunnnit,  becomes  a  reddish 
limestone  or  marble.  These  strata,  which  liave  yielded  a 
Cambrian  fauna,  were  by  C.  B.  Adams  referred  to  the 
horizon  of  the  Medina  and  Clinton,  and  by  Logan,  in 
1859,  were  said  to  belong  to  the  summit  of  the  Hudson- 
River  group,  or  possibly  to  a  still  higher  horizon.  These 
rocks  were,  however,  in  1855,  assigned  Ly  Emmons  to  a 
position  still  lower  than  the  green  sandstones,  and  were 
supposed  to  represent  the  Potsdam  horizon  of  the  Cham- 
plain  division  ;  while  the  remaining  portion  of  the  Upper 
Taconic  was  regarded  as  the  equivalent  to  the  Calciferous 
Sand-rock.  The  Red  Sand-rock  in  western  Vermont  is 
brought  up  by  a  dislocation,  and  the  higher  members  of 
the  Champlain  divi^iion  appear  to  pass  conformably 
beneath  it  to  the  eastward.  The  same  conditions  are 
met  with  in  the  Cambrian  beds  at  Tro}-,  New  York, 
studied  by  Ford,  which  there  overlie  the  Loraine  shales, 


,1'  ' ' 


4  '" 


'  IH 

M 

HI ' 

II 

HI  P^H 

II 1 

H  ii  ilil 

H  III  III  II 

Bli    n  '  idl^^^l  ' 

n 

ISIlHyiiili 

hhh    n!  'H  mRHIIwE 

^HI^-1 

^^^H      lull  'lE'lllnlHltw 

mi  nm 

^^^M        wM  'luillfflllllH 

wm  1  i  iw 

■IHIIj  HB'  ^'^'-Sv 

^HH  ma'-  l'i-|w 

HM^Ki'  HB,  ^'''44^^H 

wClltSi    X          '  'RrVB 

M^^^^^^^^^^Mi 

ili  ^  '  ''"'it 

hhhh 

■HnU     n  ■        is  ji| 

|H||m  IpHv^Hlw 

llilillil 

MB    »f''i  HH    liHili 

mm  t'\     1  i IH    'llliiniBiil 

1 IIH 

H      Jl 

lH  1111111  il 

Win''    1 

'  flffll       liraiplJ'l 

mKM  { 

i        t   i 

Ww   Ut             rat 

KKbI     i.      f-^^*   In 

^  '     '•^If 

594 


THE  TACONIO  QUESTION   IN  OEOLOOY. 


[xr. 


aiul  were  by  Billings  assigned  to  the  same  geological 
horizon  us  the  lied  Sund-rock,  witli  the  name  of  Lower 
Potsdam.  The  outcrop  of  these  strata  in  Georgia,  Ver- 
mont, according  to  Logan,  exposes  a  thickness  of  not 
less  than  2:^00  feet,  in  the  lower  part  of  which  are 
included  the  argillaceous  beds  holding  Olenellus,  with 
Conocephalitcs  and  Obolella.  The  late  results  of  Walcott 
in  the  study  of  the  Cambrian  rocks  in  North  America 
•will  be  noticed  farther  on,  after  §  138. 

VI.  —  THE  UPPER  TACONIO  IN  CANADA. 
§  103.  We  are  now  prepared  to  notice  the  studies  of 
this  Gra}  wacke-belt  in  its  extension  through  Canachi, 
from  Vermont  to  the  St.  Lawrence.  Logan,  who,  in  1845, 
published  a  preliminary  account  of  the  geolog}'  of  Can- 
ada, expressed  therein  the  opinion  that  the  contorted  strata 
at  and  near  the  city  of  Quebec,  which  are  those  of  the  belt 
in  question,  were  older  than  the  adjacent  horizontal  (Tren- 
ton) limestones ;  but  in  a  foot-note  referred  favorably  to 
the  view  (which  had  been  maintained  by  Ennuons  in  1842) 
that  they  were  newer  rocks.  These  contorted  strata,  con- 
sisting of  argillites,  sandstones,  conglomerates,  and  lime- 
stones, were,  during  the  next  ten  years,  traced  in  Canada 
from  Quebec  northeastwaixl  along  the  right  bank  of  the 
lower  St.  Lawrence,  and  southwestward  to  the  valley  of 
Lake  Champlain ;  forming  a  belt  from  near  Quebec  south- 
ward along  the  northwest  base  )f  the  crystalline  schists 
of  the  Green  Mountain  range.  They  were  recognized  by 
the  Canadian  survey  as  forming  a  part  of  the  Graywacke- 
belt  of  Eaton,  and,  in  accordance  with  the  view  of  Mather, 
and  the  earlier  view  of  Emmons,  were  referred  to  the  upper 
part  of  the  Champlain  division,  and  declared  to  embrace 
the  so-called  Hudson-River  group,  and  the  immediately 
succeeding  strata;  including  the  representative  of  the 
Oneida,  to  which  the  sandstones  of  Sillery  were  supposed 
to  belong.  The  organic  remains  as  yet  found  in  the  belt, 
in  Canada,  were  in  limestone-pebbles  in  a  conglomerate  at 


.OY.  »*•• 

no    geological 
,,ne  oi  Low^^i" 
Goorgiii^  Vci- 
jkiiess   of  ""^ 
o£    which   are 
HcueUiw,  with 
lilts  oi  Walcolt 
j^orth  America 


\.NADA. 

e  tlie  studies  of 
ivougii  Cauaila, 
an,  who,  in  18-15, 
geoU>gy  of  Cau- 
3  contorted  strata 
those  of  tiie  belt 
horizontal  (Tren- 
rred  favorably  to 
Emmons  in  1842) 
torted  strata,  con- 
lerates,  and  Ume- 
tvaced  in  Canada 
,ight  bank  of  the 
a  to  the  valley  of 
lear  Quebec  south- 
crystalline  schists 
5^ere  recognized  by 
of  the  Graywacko- 
the  view  of  Mather, 
eferred  to  the  upper 
eclared  to  embrace 
id  the  immediately 
n-esentative   of  the 
llevy  were  supposed 
et  found  in  the  belt, 
,u  a  conglomerate  at 


xi.i 


UPrEIl   TACONIC   IN   CANADA. 


rm 


Pointo  Lnvia,  which  wore  orrnneously  supposed  to  bo 
derived  f'/om  tlio  Trenton;  and  ccrtahi  forms  oceurring 
ill  a  liiiiiistono  at  Phillipsburgh,  near  Lake  Chaiii[)huii, 
also  regarded  as  of  Trenton  ago.  In  ISof),  were  first 
described,  by  James  Hall,  the  gra[)t()lites  of  Pointj  Levis, 
then  8i)oken  of  by  liim  as  coming  from  "near  tlio  suiiiniit 
of  the  Hndson-lliver  group  " ;  to  which  horizon,  consid- 
ered as  that  of  the  Lorainc  shales,  tliey  were,  on  strati- 
grapiiical  grounds,  assigned  by  Logiin. 

§  104.  As  early  as  1840,  however,  as  we  liave  seen, 
Emmons  had,  on  stratigraphical  grounds,  assigned  this 
Graywacke-belt  to  the  horizon  of  tlie  Calciferons  Sand- 
rock,  and  had  dechired  it  to  contain  certain  peculiar  rnnus 
of  graptolites  and  of  trilobit^c-s.  This  view,  which  was  ussen- 
tially  a  return  to  that  of  Eatin,  was,  however,  combated 
by  all  the  other  Americans  geologists  who  had  studied 
these  rocks  in  Canada  and  in  Vermont;  C.  li.  Adams, 
W.  B.  Rogers,  and  W.  E.  Logan  uniting,  on  alleged 
structural  grounds,  to  place  these  rocks  at  the  summit  of 
the  Champlain  division,  or  in  the  Second,  instead  of  the 
First  Graywacke. 

§  105.  Tt  was  not  until  1856  that  the  present  writer 
discovered  in  association  with  the  graptolitic  beds  (-f 
Pointe  Levis,  limestones  containing  a  hitherto  unobserved 
trilobitic  fauna,  the  examination  of  which  by  Billings 
led  him  to  the  conclusion  that  the  strata  in  question  were 
older  and  not  younger  than  the  Trenton  limestone ;  or,  in 
other  words,  that  they  belonged  to  the  First  and  not  to 
the  Second  Graywacke.  It  was  in  1861  that  Logan,  in 
a  letter  to  Barrande,  published  this  conclusion,  then 
reached,  and  at  the  same  time  admitted  the  correctness 
of  the  later  view  of  Emmons,  for  which  this  geologist  had 
contended  alone  during  fifteen  years,  namely,  —  that  the 
belt  of  disturbed  rocks  which  in  Canada  and  in  Vermont 
had  been  called  the  Hudson-River  group,  was  in  reality 
the  stratigraphical  equivalent  of  the  lower  members  of  the 
Champlain  division,  and  older  than  the  Trenton  lime- 


i     m 


596 


THE  TACONIC   QUESTION  IN  GEOLOGY. 


[xr. 


stones.  These  strata  were  the  Upper  Taconic  of  Emmons, 
which  he  had  already  in  1860  declared  to  be  the  equiva- 
lent of  the  rocks  holding  the  first  or  Primordial  fauna  of 
Barrande.     (§  17,  and  ante,  p.  586.) 

§  106.  The  contact  of  these  rocks  near  Quebec  with  the 
underlying  gneiss  is  concealed  by  the  horizontal  Trenton 
limestone  of  the  region.  The  green  sandstone  of  Sillery 
here  lies  upon  the  other  members  of  the  Graywacke 
series,  and  since  this  had  been  regarded  as  the  Oneida 
sandstone,  overlying  Loraine  shales,  the  whole  series  was 
supposed  to  be  in  its  natural  order  of  succession.  Hence 
it  was  that,  while  admitting  the  change  of  horizon  f 
these  rocks  from  above  to  below  the  Trenton  limestone, 
the  Sillery  sandstone,  as  it  was  henceforth  called,  was 
placed  at  the  summit,  and  the  limestones  and  graptolitic 
si  ites  of  Pointe  Levis,  to  which  the  name  of  the  Levis 
division  was  given,  at  the  base  of  the  series ;  an  interme- 
diate portion  receiving  the  name  of  the  Lauzon  division. 
The  real  order,  however,  as  described  both  by  Emmons  in 
Vermont,  and  by  Murray  in  Newfoundland  was  the  reverse 
of  this,  and  the  Sillery  sandstone  was,  in  truth,  the  oldest 
member  of  the  series  here  displayed.  Logan,  as  we  have 
seen,  maintained  that  the  typical  section  of  southeast- 
ward-dipping strata  at  Quebec,  estimated  by  him  to 
measure  7000  feet,  was  the  southeast  side  of  an  eroded 
anticlinal,  and  represented  the  rocks  of  his  Quebec  group 
in  their  natural  order ;  the  Levis  division  at  the  base  and 
the  Sillery  at  the  summit.  I  have  long  since  endeavored 
to  show,  alike  on  structural  and  on  paleontological 
grounds,  that  this  view  is  erroneous,  and  that  we  have 
here  an  inverted  succession.  The  true  position  of  tlie 
Sillery  is  at  the  base  of  the  series,  and  we  here  find 
exposed  the  eroded  surface  of  the  northwest  side  of  an 
overturned  anticlinal,  by  which  the  Sillery  sandstone  is 
made  to  overlie  the  younger  members  of  the  Graywacke 
series.*     The  succession   is  thus  brought  into  harmony 

»  Harper's  Annual  Record  for  1876,  p.  xcviii.,  and  for  1877,  p.  167. 


XI.] 


UPPER  TACONIC  IN  CANADA. 


697 


3GY.  ^"^• 

ic  of  Emmons, 
be  the  equiva- 
ordial  fauna  of 

Quebec  with  the 
Lzontal  Trenton 
stone  of  SiUery 
the  Graywacke 
I  as  the  Oneida 
whole  series  was 
jcession.  Hence 
re  of  horizon  i 
'enton  limestone, 
^orth  called,  was 
es  and  graptolitic 
ame  of  the  Levis 
n-ies;  an  interme- 
.  Lauzon  division, 
pth  by  Tilmmons  m 
,nd  was  the  reverse 

,u  truth,  the  oldest 
Logan,  as  we  have 
,tion   of  southeast- 
Tiated    by  him    to 
side  of  an  eroded 
f  his  Quebec  gvouv 
,ion  at  the  base  and 
ig  since  endeavorec 
on    paleontologicul 
and  that  we  have 
:rue  position  of  the 
,  and  we  here  find 
northwest  side  of  an 
SiUery  sandstone  is 
rs  of  the  Graywacke 
•ought  into  harmony 
,11.,  and  for  1877,  P- 16^' 


V.  ith  tliat  determined  by  Eaton,  and  by  Emmons,  in  many 
sections  farther  south.  This  series,  which  had  been 
previously  called  the  Hudson-River  group,  was  now  by- 
Logan,  and  the  Canada  geological  survey,  named  the 
Quebec  group,  and  was  described  as  a  great  development 
of  strata  between  the  Trenton  limestone  and  the  Potsdam 
sandstone ;  which  latter,  Logan  conceived  to  be  repre- 
sented by  certain  black  shales,  that  in  several  localities 
appear  to  pass  beneath  the  Levis  division.  The  rocks  of 
this  series  were  now,  by  Logan  and  his  assistants,  traced 
down  the  St.  Lawrence  to  Newfoundland,  on  the  one 
hand,  and  to  the  valley  of  Lake  Champlain,  on  the  other; 
where,  however,  the  Red  Sand-rock  was  supposed  to 
represent  the  Potsdam.  The  history  of  these  investiga- 
tions I  have  elsewhere  set  forth,  in  "Azoic  Rocks,"  pp. 
81-125.  It  should  here  be  said  that  this  view,  which 
made  the  Sillery  the  youngest  member  of  the  series,  was, 
in  1862,  questioned  by  Billings,  who  inclined,  with  the 
writer,  to  place  it  at  the  base  of  the  series ;  while  its 
evident  basal  pos^'^tion  in  Newfoundland  led  Logan  also  to 
express  doubts,  and  to  look  upon  the  order  assumed  by 
him  as  simply  provisional.* 

§  107.  It  remained,  however,  to  determine  how  far 
this  identification  with  the  First  Graywacke  applied  to 
the  rocks  farther  south,  in  the  valley  of  the  Hudson,  to 
which  the  name  of  the  Hudson-River  group  had  first  been 
given ;  and  which  had  been  declared,  alike  by  Eaton, 
Emmons,  and  Mather,  to  be  geographically  and  stratigraph- 
ically  identical  with  the  similar  rocks  in  Vermont  and 
in  Canada.  These  rocks  in  the  Hudson  valley  had  been 
by  Mather  assigned  to  the  horizon  of  the  Second  Gray- 
wacke, and  from  the  occurrence  in  portions  of  them  of  the 
fauna  of  the  Loraine  or  Pulaski  shales,  he,  with  Vanuxem, 
had,  as  we  have  seen,  been  led  to  emi)loy  the  names  of 
Hudson  slates  and  Hudson-River  group  as  synonymous 

*  Billings,  Paleozoic  Fossils,  1865.  p.  69,  and  Logan,  Geology  of 
Canada,  180:1.  p.  880. 


1'# 


\:\ 


698 


THE  TACONIC  QUESTION   IN  GEOLOGY. 


[XI. 


J     I 


with  that  of  Loraine  shales.  The  opposition  between  the 
view  of  Mather,  on  the  one  hand,  and  that  of  Emmons, 
now  adopted  by  Logan,  on  the  other,  as  to  the  horizon  of 
the  so-called  Hudson-River  group,  was  thus  radical  and 
complete. 

§  108.  A  question  here  arises  whether  it  might  not  be 
possible  to  reconcile  these  two  seemingly  contradictory 
views  by  showing  the  belt  of  disturbed  strata  in  question 
to  include  both  the  First  and  the  Second  Graywacke. 
These,  as  we  have  seen,  were  declared  to  resemble  each 
other  so  closely  as  to  be  scarcely  distinguishable  save  by 
the  fact  that  the  latter  overlies  the  Trenton  limestone 
(§  7).  If  now,  from  any  cause,  this  limestone  should  be 
absent,  or  should  not  appear  in  its  usual  character,  it 
might  vc  r>  well  happen  that  the  Second  should  appear  to 
succeed  directly  the  First  Graywacke.  That  such  a 
condition  of  things  occurs  in  the  disturbed  region  east  of 
the  Hudson,  had  already  been  affirmed  by  Emmons  in 
1846.  As  I  have  elsewhere  pointed  out  ("  Azoic  Rocks," 
page  49),  he  then  asserted  the  existence  in  ihis  region  of 
three  distinct  series  of  rocks:  I.  The  Lower  Taconic  or 
Taconian  limestone  and  slates.  XL  The  First  Graywacke, 
or  Upper  Taconic,  resting  in  apparent  unconformity  upon 
the  former,  and  itself  partially  eroded  before  the  deposi- 
tion of  III.,  which  latter  consists  of  shales  and  sandstones 
belonging  to  the  upper  portions  of  the  Chumplain  division, 
or  the  Second  Graywacke,  and  rests  unconformably,  in 
many  localities  east  of  the  Hudson,  both  on  I.  and  II. ; 
having  itself  been  subseqv.ently  disturbed  and  eroded. 

§  109.  These  observations  accord  with  many  others  to 
show  the  existence  of  ut  least  two  important  stratigraphieal 
breaks,  with  unconformity,  in  this  eastern  region  :  the  first 
between  the  Taconic  and  the  First  Graywacke,  already 
pointed  out  by  Eaton,  and  the  second  at  the  summit  of 
the  same  Graywacke  series;  thereby  dividing,  in  this 
eastein  region,  the  Champlain  division  into  two  distinct 
periods,  the  second  one  of  which  began  with  the  depo- 


XL] 


UPPER  TACONIC   IN   CANADA. 


599 


sition  of  tlie  Trenton,  or,  rather,  with  tliat  of  the  immedi- 
jitely  subjacent  Chazy  limestone. 

The  Laurentian  regions  of  the  Adirondacks  and  the 
Laurentides  were  not,  at  this  early  time,  as  has  been  so 
often  said,  the  nucleus  of  a  growing  continent,  but  higher 
portions  of  a  subsiding  one.  Upon  its  ancient  gneiss  we 
find  reposing  directly,  in  different  localities,  the  Potsdam, 
the  Calciferous,  the  Chazy,  and  the  Tientou  subdivisions. 
The  dei)osition  of  the  Trenton  marks  a,  time  of  subsi- 
dence, daring  which,  along  the  Laurentides,  the  sea 
extended  far  and  wide  to  the  northward,  and  the  marine 
limestones  of  the  Trenton,  overlapping  the  lower  members 
of  the  Cham  plain  division,  were  laid  down  (in  the  regions 
to  the  north  of  Lake  Ontario  and  of  the  lower  St. 
Lawrence,  as  far  eastward  as  the  basin  of  Lake  St.  John 
on  the  Saguenay),  directly  on  the  submerged  primary  or 
eozoic  rocks.  After  this  period,  and  before  the  deposition 
of  the  succeeding  mechanical  sediments,  extensive  move- 
ments took  place  in  the  region  of  the  Ottawa  and  Cham- 
plain  valleys,  and  still  farther  south,  which  serve  to 
throw  light  upon  the  problem  before  us. 

§  110.  A  striking  illustration  of  this  disturbance  is 
shown  on  Logan's  larger  geolcg'cal  map  of  Canada,  in 
1866,  where,  immediately  south  and  east  of  the  city  of 
Ottawa,  appears  an  outlier  of  Utica  slate,  overlaid  by 
gray  calcareous  sandstone,  holding  the  fossil  remains  of 
the  Loraine,  and  associated  with  red  slates ;  the  two  possi- 
bly representing  the  Oneida  and  the  Medina.  This  out- 
lier, with  a  length  of  about  twenty  miles  from  east  to 
west,  reposes  transgressively  alike  upon  the  Trenton, 
Chazy,  and  Calciferous  subdivisions.  All  three  of  these, 
witii  a  slight  eastward  dip  towards  the  centre  of  the 
Ottawa  basin,  appear  successively,  in  passing  from  west 
to  east  along  the  southern  border  of  this  unconformably 
overlying  area  of  newer  strata,  which  are  here  preserved  by 
having  been  let  down  along  the  north  side  of  an  east 
and  west  dislocation ;  thus  testifying  to  a  former  exten- 


V 


:i,wrrTiiiii 


600 


THE  TACONIG   (iUESTION  IN  GEOLOGY. 


[XI. 


,r''^ii! 


iKS 


sion  of  the  Second  Graywacke  over  this  area,  where  it  lies 
un conformably,  not  only  on  the  Calciferous  Sand-rock 
(the  representative  of  the  First  Graywacke),  but  on  the 
Trenton  limestone  itself.  For  farther  references  to  the 
'.le tails  of  tliis  region,  which  was  carefully  mapped  by 
Logan,  see  "Azoic  Rocks,"  page  50.  We  have  here,  in 
tlie  valley  of  the  Ottawa,  evidences  of  the  same  conditions 
as  v/ere  described  by  Emmons  in  that  of  the  Hudson; 
namely,  the  unconformable  superposition  of  the  upper 
members  of  the  Champlain  division  upon  the  lower  ones ; 
a  break  occurring  at  the  summit  of  the  Trenton.  It  is 
impossible  not  to  connect  "these  conditions  in  tlje  Ottawa 
and  Hudson  valleys  with  those  already  noticed  in  eastern 
Pennsylvania,  and  in  Orange  County,  New  York,  where 
the  Oneida  sandstone,  which,  as  we  have  seen,  is  continu- 
ous with  the  upper  part  of  tlie  Loraine  shales,  is  found  to 
rest  unconformably  upon  thu  strata  of  the  First  Gray- 
wacke. 

§  111.  Considerable  movements  are  thus  seen  to  have 
marked  both  the  beginning  and  the  close  of  the  Chazy- 
Trenton  period,  and  it  is  evident  that  the  absence,  in  any 
district,  of  the  characteristic  limestone  of  this  time,  be- 
tween the  First  and  Second  Graywackes,  might  result 
either  from  non-deposition  or  from  erosion.  Evidence  of 
the  latter  is  afforded  in  the  area  just  described  in  the 
Ottawa  basin ;  while,  at  the  same  time,  there  is  not 
wanting  evidence  that  this  limestone-mass,  so  well  marked 
by  its  thickness,  and  the  persistence  of  its  lithological 
character  over  great  areas  in  eastern  North  America, 
else wi ere  thins  out,  and  either  disappears  entirely,  or 
loses  its  ordinary  lithological  characters.  Thus  while  in 
Canada,  at  points  as  widely  separated  as  Beauport,  Mont- 
real, Ottawa,  Lake  Simcoe,  and  the  shores  of  Lake  Huron, 
it  appears  with  a  thickness  of  from  600  to  750  feet  (being 
everywhere  followed  by  the  Utica  and  Loraine  sluiles),  it 
is  in  Lewis  County,  New  York,  diminished  to  300  feet,  at 
Trenton  Falls  to  100  feet,  and,  it  is  said,  to  thirty  feet  in 


GY.  t**' 

,  wliere  it  lies 
us  Sand-rock 
),  but  on  tlie 
srences  to  tlie 
y  mapped  by 

have  here,  in 
Line  conditions 

the  Hudson; 

of  the  upper 
he  lower  ones ; 
rrenton.  It  is 
in  the  Ottawa 
aced  in  eastern 
w  York,  where 
een,  is  continu- 
,les,  is  found  to 
;he  First  Gray- 

ius  seen  to  have 
e  of  the  Chazy- 
absence,  in  any 
)f  this  time,  be- 
js,  migbt  result 
n.     Evidence  of 
described  in  the 
le,  there   is  not 
;,  so  well  marked 
■   its  lithological 
North   America, 
lears  entirely,  or 
Thus  while  in 
Boauport,  Mont- 
s  of  Lake  Huron, 
o  760  feet  (being 
voraine  shales),  it 
ed  to  300  feet,  at 
.,  to  thirty  feet  in 


XI.] 


UPPER  TACONIC   IN  CANADA. 


601 


the  Mohawk  valley  ;  tliinning  out  and  disappearing  to  the 
southeast,  according  to  Conrad;  but,  as  will  subsequently 
ap£/ear,  probably  represented  along  this  eastern  border 
by  argillaceous  beds,  which,  but  for  their  organic  remains, 
would  not  be  recognized  as  of  Trenton  age. 

§  112.  The  bearing  of  the  paleontological  investigations 
made  by  the  geological  survey  of  Canada  on  the  question 
of  the  age  of  the  eastern  Graywacke,  or  so-called  Hudson- 
River  group  of  rocks,  v  as  discussed  by  James  Hall,  in  a 
note  to  his  "Geology  of  Wisconsin,"  in  1862  (page  443). 
He  there  alluded  to  the  evidence  furnished  by  organic 
remains  found  in  the  Hudson-River  slates  in  Vermont 
and  Canada,  "which  prove  conclusively  that  these  slates 
are  to  a  great  extent  of  older  date  than  the  Trenton  lime- 
stone," though  probably  newer  than  the  Potsdam.  He 
moreover  remarked  that  "  the  occurrence  of  well  known 
forms  of  the  second  fauna  ...  in  intimate  relation  with, 
and  in  beds  apparently  constituting  a  part  of  the  serie?, 
along  the  Hudson  River,  requires  some  explanation. 
Looking  critically  at  the  localities  in  the  Hudson  valley 
wliicli  yield  the  fossils,  we  find  them  of  limited  and  of 
almost  insignificant  extent.  Some  of  tliem  are  on  the 
summits  of  elevations,  which  are  synclinal  axes  .  .  . 
where  the  remains  of  newer  formations  would  naturally 
occur.  Others  are  apparently  unconformable  to  the  rocks 
below,  or  are  entangled  in  the  folds  of  the  strata  .  .  .  while 
the  enormous  thickness  of  beds  exposed  is  almost  desti- 
tute of  fossils."  In  view  of  all  these  facts,  Hall,  while  still 
retaining  the  name  of  Hudson-River  group  as  the  desig- 
nation of  the  fossiliferous  strata  which  elsewhere  are 
found  to  occupy  a  horizon  between  the  Utica  slate  and 
the  Oneida  sandstone  (otherwise  called  Pulaski  and 
Loraine  shales),  concludes  that  the  name  of  Hudson-River 
group  cannot  properly  be  extended  to  the  great  mass  of 
strata  which  have  hitherto  borne  that  name,  and  which, 
according  to  him,  "are  separated  from  the  Hudson-River 
group  proper  by  a  fault  not  yet  fully  ascertained." 


.«i    <*« 


Vli.';!:!i; 


ml 


n    ';" 


g.!^iiii» 


602 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


§  113.  It  should,  however,  be  remembered  that  al- 
though the  Hudson-River  group  was,  through  the  paleon- 
tological  publications  of  the  New  York  survey,  identified 
with  the  Loraine  shales  only,  the  name,  as  at  first  given 
by  Vanuxem,  was  made  to  include  two  divisions,  the 
lower  of  whicli,  as  he  showed,  was  distinct  from  the  upper, 
as  appeared  by  its  different  geographicid  distribution. 
That  these  two  divisions  of  the  Hudson-River  group  were 
supposed  by  him  to  be  associated  with  a  still  older  series, 
lithologically  resemblijig  them,  would  appear  from  Van- 
uxem's  language,  when  lie  wrote  of  "the  difficulty  of 
separating  or  distinguishing  the  slaty  and  schistose  mem- 
bers of  the  Hudson-River  group  from  those  of  greater 
age,  with  which,  along  their  eastern  border,  the  two  (sic) 
are  more  or  less  really  or  apparently  blended." 

§  114.  Hall,  while  thus  admitting  the  existence  of  an 
apparent  unconformability  between  the  older  and  the 
newer  fossiliferous  rocks  in  this  disturbed  region,  fell 
back  on  Logan's  explanation,  and  imagined  the  juxtapo- 
sition of  the  two  series  to  be  effected  by  a  break  of  the 
strata,  with  an  uplift  on  the  eastern  side,  by  which  the 
rocks  of  pre-Trenton  age  were  brought  up,  and  were 
sometimes  found  in  contact  with  the  Trenton  or  Utica 
divisions,  at  others  with  the  Loraine,  and,  perhaps,  even 
with  the  still  higher  beds  of  the  Oneida.  I  have  else- 
where discussed  ac  length  this  hypothesis  of  a  single  great 
fault,  with  an  upthrow  of  7000  feet,  imagined  by  Logan 
to  extend  from  Alabama  to  the  northeast  extremity  of 
the  continent,  in  Gaspd ;  and  having  shown  its  great  im- 
probability both  geographically  and  stratigraphically,  have 
maintained,  for  ten  years  past,  the  simpler  explanation  of 
an  unconformity  between  the  First  Graywacke  and  the 
succeeding  members  of  the  paleozoic  series.  ("Azoic 
Rocks,"  pp.  121-125.)  Evidences  are  there  given  that 
movements  of  the  earth's  crust  in  these  regions  immedi- 
ately precede!  the  Trenton  age,  and  that  u[)on  the  folded, 
eroded,  and  submerged  strata  of  the  First  Graywacke,  as 


XI.] 


UPPER  TACONIC   I"   CANADA. 


603 


upon  the  Taconiau  and  still  elder  series,  there  wero  sub- 
sequently deposited  the  Trenton  limestones.  Where  these 
limestones  were  afterwards  removed  by  denudation,  or 
where,  to  the  eastward,  they  thin  out  and  disappear,  we 
may  expect  to  find  the  Loraine,  or  the  succeeding  Oneida 
strata,  in  direct  superposition  upon  these  older  rocks. 

§  115.  In  1863,  Logan,  having  followed  southward  into 
Vermont  the  Graywacke-belt,  to  which  he  had  then  given 
the  name  of  the  Quebec  group,  proceeded,  in  company  with 
James  Hall,  to  examine  the  same  rocks  in  eastern  New 
York ;  where  they  were  now  described  by  him,  as  they 
had  been  by  Emmons,  as  sandstones  and  conglomerates, 
generally  with  argillites,  sometimes  red  and  green,  and 
with  limestones,  often  schistose  or  concretionary,  includ- 
ing the  Sparry  Lime-rock  of  Eaton.  All  of  these  were 
now  declared  by  Logan  to  belong  to  the  Quebec  group, 
which  was  said  by  him  to  occupy  nearl_y  the  whole  of 
Columbia,  Rensselaer,  and  Dutchess  Counties  ;  the  Sillery 
division  being  largely  displayed  in  the  first-named 
of  these,  but  scarcely  appearing  south  of  it.  To  the 
westward,  in  approaching  the  River  Hudson,  these  rocks 
were  declared  to  be  replaced  by  lithologically  distinct  and 
more  recent  strata,  referred  to  the  Loraine  shales ;  a  narrow 
belt  of  which  was  traced  along  the  east  side  of  the  river 
to  a  point  a  little  above  Hyde  Park,  where  the  boundary 
of  the  two  divisions  crosses  to  the  west  bank.  The  strata 
on  both  shores  from  thence  down  to  the  gneiss  of  the  High- 
lands were  referred  by  Logan  to  the  Quebec  group. 

§  116.  Logan,  however,  as  we  have  seen,  assumed  the 
Sillery  sandstone  to  be  the  sunnnit  instead  of  the  base  of 
the  First  Graywacke  ;  and  when  he  became,  at  this  time, 
acquainted  with  the  underlying  Taconiau  marbles  in 
Vermont,  and,  farther  southward,  imagined  them  to  be 
his  Levis  and  Lauzon  divisions  in  'an  altered  condition, 
and  thus  described  them  as  members  of  the  Quebec  group. 
It  yet  remains  to  determine  in  this  rej^ion  the  limits  be- 
tween the  Taconic  and  the  First  Graywacke.     We  now 


Mi    .111 


mm 


604 


THE  TACONIC  QUESTION  IS   GEOLOGY, 


[xr. 


know,  moreover,  from  the  discoveries  of  Dale,  Dwight, 
and  others,  that  still  newer  fossiliferous  strata,  of  Ordo- 
vician  age,  are  also  included  in  this  part  of  the  Hudson 
valley ;  and  that  we  have,  in  fact,  in  this  region,  the  three 
groups  of  rocks  long  since  pointed  out  by  Emmons. 
(§  108.)  The  testimonj"^  of  Logan  is  valuable  as  confirming 
that  of  Emmons,  and  of  Hall,  as  to  the  existence  of  por- 
tions of  the  Second  Graywacke  series  resting,  not  upon 
the  Trenton  limestone,  but  upon  the  older  schistose  rocks 
of  the  region ;  and  moreover,  as  showing  the  superposi- 
tion of  the  First  Graywficke  to  the  Taconian. 

§  117.  The  apparent  absence  of  the  characteristic  lime- 
stone of  the  Trenton  from  the  base  of  the  Second  Gray- 
wacke in  this  region  may  be  due  to  a  stratigraphical 
break  and  erosion  at  the  close  of  the  Trenton  period,  as 
we  have  seen  in  the  Ottawa  basin.  Two  other  explana- 
tions are  suggested  by  the  thinning-out  of  the  limestone- 
mass  to  the  southeast,  as  already  noticed  (§  111)  ;  one,  that 
the  region  was  beyond  the  Trenton  sea,  and  the  other  that 
the  sediments  of  this  sea  over  the  area  in  question  were 
argillaceous  beds,  resembling  rather  the  succeeding  shales 
than  the  limestone  deposited  elsewhere.  That  this  latter 
was  the  case  in  parts  of  the  eastern  region,  will  be  shown 
in  the  sequel,  but  we  shall  there  also  find  many  evidences 
of  movements  in  paleozoic  times,  subsequent  to  the  depo- 
sition of  the  Trenton. 

I  have  elsewhere  pointed  out  ("Azoic  Rocks,"  page 
123),  besides  the  post-Trenton  break  in  the  Ottawa  basin, 
the  evidence  1.1  eastern  North  America  of  not  less  than 
five  epochs,  marked  by  movements  of  the  strata,  and  by 
unconformities,  subsequent  to  the  deposition  of  the  Tren- 
ton and  Utiea  divisions.  Of  these  the  earliest,  and  the 
only  one  which  now  concerns  us,  is  that  of  which  we  see 
evidences  in  the  unconformable  superposition  of  Silurian 
beds  over  older  strata  to  the  north  and  east  of  the  Hud- 
son valley.  On  St.  Helen's  Island,  near  Montreal,  we 
find  reposing  on  the  eroded  surface  of  the  slightly  inclined 


00  Y.  ^•"'• 

Dale,  Dwiglit, 
,trata,  of  Ordo- 
of  the  Hudson 
egion,  the  three 
t   by   Emmons. 
,le  as  confirming 
xistence  of  p^^- 
esting,  not  upon 
r  schistose  rocks 
g  the  superposi- 

iiian. 

laracteristic  lime- 
he  Second  Gray- 

a  stratigraphical 
:renton  period,  as 
wo  other  explana- 

of  the  limestone- 
(§  111)  ;  one,  that 
and  the  other  tbat 
V  in  question  were 

1  succeeding  shales 
That  this  latter 

:"ion,  will  be  shown 
nd  many  evidences 
;quent  to  the  depo- 

,zoic  Rocks,"  page 
1  the  Ottawa  basin, 
ja  of  not  less  than 
i  the  strata,  and  by 
osition  of  the  Tren- 
he  earliest,  and  the 
hat  of  which  we  see 
•position  of  Silurian 
,nd  east  of  the  Hud- 
near  Montreal,  we 
the  slightly  inclined 


XL] 


UPPEll   TACONIG   IX   (JANADA. 


G05 


Utica  slates,  a  portion  of  fossiliferuus  limestone  associated 
with  a  doloniitic  conglomerate.  The  fauna  in  the  lime- 
stone is  referred  to  the  age  of  the  Lower  Helderberg; 
while  the  acc(jmpanying  conglomerate  contains  forms 
which  belong  rather  to  the  CI  niton  and  Niagara  divisions 
of  the  Silurian,  and  liolds  at  the  same  time  pebbles  of 
fossiliferous  Trenton  limestone,  with  others  apparently  of 
Potsdam  sandstone,  Utica  shite,  and  red  sandstone  and 
shale,  resembling  those  of  the  Medina ;  the  whole  mingled 
with  pebbles  of  Laurentian  gneiss,  and  of  igneous  rocks, 
giving  evidence  of  a  period  of  disturbance,  and  considera- 
ble erosion  of  the  older  rocks.  Other  masses  of  similar 
conglomerate  are  found  elsewhere  in  the  vicinity,  in  ouo 
case  holding  Silurian  fossils,  resting  on  various  members 
of  the  Champlain  division,  and  on  the  Laurentian  gneiss. 

Another  mass  of  Lower  Helderberg  limestone  is  met 
with  on  the  flanks  of  lieloeil  Mountain,  an  eruptive  mass 
which  breaks  through  the  Loraine  shales  in  the  Richelieu 
valley.  In  tlie  distribution  of  these,  and  of  similar  areas 
of  fossiliferous  limestones,  we  have  the  evidences  of  a 
Silurian  sea,  which  extended  from  the  Helderberg  region 
in  New  York,  not  only  through  the  valleys  of  the  Hudson 
and  Lake  Champlain  to  that  of  the  St.  Lawrence,  but  also 
through  those  of  the  Connecticut,  the  St.  Fjancis  and  the 
Chaudidre,  and  thence  to  Gaspd  ;  depositing  its  sediments, 
with  their  characteristic  fauna,  unconformably  over  rocks 
of  very  different  ages.  We  have  similar  evidence  that 
the  Chazy-Loraine  or  Ordovician  sea  had  already,  in  like 
manner,  extended  over  parts  of  this  region,  leaving  its 
fossiliferous  sediments  spread  unconformably  over  Cam- 
brian and  pre-Cambrian  strata. 

§  118.  A  section  from  Crown  Point,  New  York,  acrcKss 
the  southern  part  of  Lake  Champlain  eastward  to  Brid- 
port,  Vermont,  which  was  studied  in  detail  by  Wing  and 
by  Billings,  presents,  in  its  western  portion,  the  whole 
succession  of  the  Champlain  subdivisions,  from  the  Pots- 
dam to  the  Loraine  shales.     Farther  eastward  on  this  line, 


■i  '^■■l.i'^ 


!l  t^  ■  :l 


606 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[Xl. 


'!  I'' 


a  great  dislocation  brings  up  the  Red  Sand-roclc,  with 
Olenellus,  causing  it  to  overlie,  in  seeming  conformity, 
the  Loraine  shales.  This  sand-rock  is  followed  to  the 
eastward  by  limestones  holding  the  fauna  of  the  Calci- 
ferous  Sand-rock,  with  other  forms  like  those  of  the  Levis 
limestone.  To  these  succeed  other  limestones,  with  an 
abundani  Trenton  fauna,  interrupted  by  a  second  fault, 
which  again  brings  up  the  Levis  beds;  the  Sillery  sand- 
stone being  unrepresented,  unless  possibly  by  the  Red 
Sand-rock  to  the  we?t.  For  a  summary  of  the  observa- 
tions on  this  section,  and  reference  to  the  original  paper, 
see  "  Azoic  Rocks,"  page  119. 

§  119.  Other  examples  of  an  extension  of  the  Ordo- 
vician  sediments  eastward  are  found  in  the  province  of 
Quebec,  in  various  localities  along  the  disturbed  region 
northeastward  from  Lake  Champlain.  Lying  alike  among 
the  uncrystalline  strata  of  the  Graywacke  series,  and  the 
older  crystalline  rocks  to  the  southeast  of  them,  there  are 
met  with,  in  many  localities,  carbonaceous  shaly  beds, 
more  or  less  calcareous,  containing  organic  remains  of 
Ordovician  age.  These  strata,  probably  never  very  con- 
siderable in  amount,  have,  however,  rarely  escaped  erosion, 
except  in  localities  where,  as  the  result  of  the  folds  and 
dislocations  already  noticed,  they  have  been  protected  by 
the  overlying  or  adjacent  older  strata,  beneath  which 
they  often  seem  to  pass  with  an  eastward  dip.  As  studied 
at  Farnham,  in  the  province  of  Quebec,  they  thus  appeared 
to  be  more  ancient  than  the  Graywacke  series,  and  were 
described  by  Logan  as  portions  of  Potsdam  rocks  under- 
lying the  Quebec  group.  The  black  slates  of  this  locality, 
however,  contain,  according  to  Billings,  besides  unde- 
scribed  graptolites,  Ptilodictya  and  trilobites  of  the  genera 
Ampyx,  Dalmanites,  Lichas,  Triarthrtis,  and  Agnostus; 
and  were  hence  referred  by  him  to  the  Trenton  or  the 
Utica  division  of  the  New  York  system.  Similar  black 
slates  appear,  in  like  manner,  to  pass  beneath  the  crystal- 
line schists  which  lie  to  the  east  of  the  Graywacke-belt  in 


.OQY.  I**' 

land-rock,  with 
ing  conformity, 
ollowed  to  the 
la  of  the  Calci- 
ose  of  the  Levis 
stones,  with  an 
a  second  fault, 
the  Sillery  sand- 
bly  by  the  Red 
J  of  the  observa- 
e  original  paper, 

ion  of  the  Ordo- 
i  the  province  of 
disturbed  region 
,ying  alike  among 
ike  series,  and  the 
)f  them,  there  are 
seous  shaly  beds, 
•ganic  remains  of 
y  never  very  con- 
y  escaped  erosion, 
t  of  the  folds  and 
been  protected  by 
,a,  beneath   which 
ddip.    As  studied 
they  thus  appeared 
ke  series,  and  were 
tsdam  rocks  under- 
tes  of  this  locality, 
ngs,  besides   unde- 
jbites  of  the  genera 
us,   and  Aonostus ; 
ae  Trenton  or  the 
em.     Similar  black 
aeneath  the  crystal- 
Gray  wacke-belt  in 


XI.] 


UlTEU  T  A  CONIC   IN  CANADA. 


GOT 


this  region,  and  were  by  Logan  adduced  as  proofs  of  the 
view  then  maintained  by  the  geological  survey  of  Canada, 
tliat  the  crystalline  locks  in  (juestiou  were  nothing  more 
than  portions  of  this  same  Graywacke  in  an  altered  con- 
dition. 

The  fallacy  of  this  view  I  have  long  since  shown,  and 
have  pointed  out  the  nature  of  the  stratigraphical  acci- 
dents by  which  this  seeming  inversion  has  been  brought 
dbout.  Selvvyn,  of  the  geological  survey  of  Canada,  lias 
more  recently  furnished  additional  facts  regarding  the 
distribution  of  these  fossiliferous  shales ;  outliers  of 
which  have  been  observed  at  various  localities  in  eastern 
Canada,  among  Ihe  crystalline  schists,  especially  along 
the  west  side  of  a  line  of  fault,  with  an  upthrow  on  the 
east  side,  extending  through  Stukley  and  Ely.  Similar 
fossiliferous  beds  are  found  in  Tingwick  and  Arthabaska, 
and  also  near  Richmond ;  where  a  narrow  belt  of  black 
shales,  with  Triarthrns  and  other  organic  forms,  is  found 
lying  to  the  east  of  the  crystalline  schists  of  the  region. 
The  latter  are  a  second  time  brought  up  on  the  eastern 
border  of  these  shales,  and  soon  pass  beneath  the  argillitea 
of  the  Windsor  basin  (§  81).  In  this  connection  it  may 
be  noticed  that  Dodge  has  found,  still  farther  to  the  east- 
ward, in  Penobscot  County,  Maine,  black  shales  holding 
graptolites,  which  are  regarded  by  him  as  species  belonging 
to  the  Utica  slate.* 

§  120.  It  was  said  at  the  commencement  of  this  essay 
that  the  Upper  Taconic  rocks  have  been  known  both  as 
the  Hudson-River  group  and  the  Quebec  group.  This 
statement  we  have  justified  in  the  preceding  pages,  and 
are  now  prepared  to  state  succinctly  what  has  been  the 
precise  meaning  attached  to  these  two  terms,  which  have 
been  so  conspicuous  in  the  history  of  American  geology. 
The  Hudson-River  group,  by  the  admission  of  Vanuxera, 
who  first  proposed  it,  was  a  composite  one,  devised  t 
include  two,  if  not  three  divisions  of  strata,  in  part  of 
*  Amer.  Jour.  Science,  ISSl,  vol.  sxii.,  p.  434. 


-0' 


m 


.1'    ,  ll; 


a  '■ 


G08 


THE   TACONIC   yUIiSTlON    IN   GliOLOCiV. 


m 


disputed  age,  but  at  tlie  same  time  embracing  in  it.s  wppev 
portion  the  Loraine  shales.  As  tiiis  was  the  only  j)art  of 
the  group  of  vviucii  the  fauna  was  known,  the  name  of 
Loraine  shales,  in  paleontological  language,  soon  came  to 
be  regarded  as  the  equivalent  of  lludson-Uiver  group; 
and  thus  the  fact  of  its  heterogeneous  character,  clearly 
stated  by  Vanuxem,  was  lost  sight  of.  Meanwhile,  the 
name  of  Hudson-River  group  was  applied  stratigraphi- 
cally  to  the  whole  of  the  First  Graywacke  of  Eaton,  with 
its  succeeding  Sparry  Lime-rock.  This  is  seen  from  the 
language  of  James  Hall,  who,  in  1857,  wrote  of  the  grap- 
tolites  found  in  slates  with  tlie  limestone  of  Pointe  Levis, 
at  that  time  assigned  by  Logan  to  this  horizon,  that  they 
are  met  witli  in  "  that  part  of  the  Hudson-Kiver  group 
which  is  sometimes  designated  as  Eaton's  Sparry  lime- 
stone, —  being  near  the  summit  of  the  group."  This 
was  the  Levis  limestone  of  Logan.* 

§  121.  The  Red  Sand-rock  of  Vermont  was  also,  at  tlio 
same  time,  regarded  as  either  forming  a  part  of  the  same 
group  or  as  closely  related  to  it.  Thus  Hall,  in  describing, 
in  1859,  the  trilobites  of  the  genus  Olenellus  found  in  shales 
intercalated  in  the  Red  Sand-rock  in  Georgia,  Vermont, 
which  he  then  referred  to  this  horizon,  wrote,  "  I  have  the 
testimony  of  Sir  William  Logan,  that  the  shales  of  this 
locality  are  in  the  upper  part  of  the  Hudson-River  group, 
or  forming  a  part  of  a  series  of  strata  which  he  is  inclined 
to  rank  as  a  distinct  group,  above  the  Hudson-River  group 
proper."  f  We  have  farther  to  mention  in  this  connection 
the  notion  of  Mather,  who  supposed  that  the  crystalline 
rocks  of  western  New  England,  including  the  crystal- 
line limestones,  "and  probably  the  associated  micaceous 
gneiss,  mica-slate,  hornblende-slate,  and  hornblende-rocks 
.  .  .  are  nothing  more  than  the  rocks  of  the  Champlain 
division  greatly  modified  by  metaraorphic  agency."     This 

*  Report  Geol.  Survey  of  Canada,  1857,  p.  117. 
t  Twelfth  Ann.  Kep.  Regents  of  the  University  of  New  York,  1859 ; 
cited  by  Barrande,  Amer.  Jour.  Scl.  (2),  xxxl,,  p.  213. 


OCiV.  ^'^• 

ng  in  itH  upper 
he  only  pttit  (if 
n,  the  luuno  vl 
e,  soon  camo  to 
u-lliver  group; 
laracter,  clearly 
Meanwhile,  the 
ed   stratigrapUi- 
a  of  Eaton,  with 
ia  seen  from  the 
vote  of  the  grap- 
of  Pointo  Levis, 
lorizon,  that  they 
dson-lUver  group 
>n'8  Sparry  lime- 
le   group."     This 

nt  was  also,  at  the 
part  of  the  same 
lall,  in  describing, 
lus  found  in  shales 
Gleorgia,  Vermont, 
vrote,  "  I  liave  the 
the  shales  of  this 
tdson-River  group, 
hich  he  is  inclined 
udson-River  group 
iu  this  connection 
hat  the  crystalline 
uding  the   crystal- 
sociated  micaceous 
d  hornblende-rocks 
of  the  Champhvin 
[lie  agency."     This 

iltyof  New  York,  1859 -, 
p.  213. 


\i. 


Ul'PKIl  TACO.sin  IN  CANADA. 


GOD 


view  was  udoptotl  by  Logan,  and  the  similar  crystalline 
rocks  of  the  (r recn-Mountuin  bolt  in  Canada  were  described 
as  belonging  io  the  iiltered  IIudsoti-Kiver  groU[). 

§  122.  The  Quebec  group,  which,  in  18(J1,  succeeded 
to  the  Iludson-Uivt-r  grouj),  iidieritod  its  traditions,  witli 
a  few  exceptions.  Its  horizon  being  now  cluinged  fr(»ni 
above  to  below  the  Trenton  limestone,  it  could,  of  course, 
no  longer  include  within  its  limits  the  fauna  of  the  Ijoraine 
shales,  belonging  to  the  Second  (xraywacko.  The  greater 
antic^uity  of  the  fauiui  of  the  Red  Sand-rock  of  Wn-mont 
having  in  the  meantime  been  recognized,  these  rocks  were 
assigned,  under  the  name  of  Potsdam,  to  a  position  be- 
neath the  so-called  Quebec  group.  To  this  lower  hori- 
zon, moreover,  Logan,  at  the  same  time,  referred  certain 
black  slates  in  Canada,  which,  though  apparently  under- 
lying the  Graywaoke  series,  have  since  been  found  of 
Ordovician  age  (§  119). 

The  Quebec  group,  as  at  first  defined,  was  nothing  more 
uor  less  than  the  First  Graywacke  of  Eaton,  with  its 
overlying  Sparry  Lime-rock ;  which  latter  is  really  an 
upper  member  of  that  Graywacke  series,  and  was  included 
with  it  by  Emmons  in  his  Upper  Taconic  division. 
Emmons  now  read  aright  the  relations  of  these  rocks,  and 
saw  that  the  sections  in  which  the  limestones  ai)pear  to 
underlie  the  massive  green  sandstones  give  an  inverted 
succession.  Logan,  however,  though  recognizing  therein 
the  existence,  in  many  cases,  of  overturned  anticlinals, 
hiverted  the  whole  series,  and  regarded  the  basal  or  Sillery 
sandstone  as  the  highest  member,  while  the  Levis  lime- 
stones were  made  the  lowest. 

§  123.  This  erroneous  view  as  to  the  succession  of  the 
strata  at  Quebec,  at  first  declared  by  Logan  to  be  merely 
provisional,  was  the  more  acceptable  to  him  for  the  reason 
that  it  could  be  m.ade  to  accord  with  the  hypothesis  that 
the  adjacent  crystalline  schists  were,  as  Mather  had  taught, 
the  altered  equivalents  of  what  was  now  called  the  Quebec 
group.     When,  as  is  sometimes  the  case,  the  Sillery  sand- 


f 


i;ii' 


■    ! 


1 


I 


i 


'tl 


^?  I 


''■■m.l 


\ik< 


1*1 


V     ( 


13  IT 
fiii.il 


610 


THE  TACONIC   QUESTION  IN   GEOLOGY. 


[XI. 


stone  was  found  alone  (as  long  before  described  by  Em- 
mons), resting  upon  the  crystalline  schists,  the  higher  and 
softer  members  of  the  Gray  vvacke  series  having  disappeared, 
Logan  supposed  that  these  schists  were  no  other  than 
shales  of  the  Sillery  (and  Lauzon)  in  an  altered  and  so- 
oulled  metamorphic  condition,  —  which,  according  to  his 
view  of  the  succession,  should  underlie  these  sandstones. 
Hence  it  was  that  the  Huronian  rocks  of  the  Notre  Dame 
range  (the  prolongation  of  the  Green  Mountains)  were 
by  Logan  called  "Altered  Quabec  group,"  long  after  it 
had  been  shown  by  the  present  writer  that  fragments  of 
these  same  eozoic  rocks  occur  in  conglomerates  with  the 
fossil iferous  strata  of  the  Levis  division  near  Quebec. 

§  124.  In  like  manner,  when  the  Sillery  sandstone  was 
found,  farther  southward  along  the  Graywacke-belt,  to 
rest  upon  the  Taconian  marbles  and  slates,  these  were  by 
Logan  declared  to  be  limestones  and  shales  of  the  Levis 
division  in  an  altered  condition  (§  116).  But  this  was 
not  all :  as  the  Levis  beds,  sometimes  through  inverted 
faults,  and  sometimes  through  dislocations,  came  to  be 
placed  beneath  the  Sillery,  so  the  black  Ordovician  slates, 
whether  in  direct  contact  with  the  Cambrian  or  with  the 
older  rocks,  were,  as  the  result  of  similar  accidents,  made 
to  underlie  the  more  ancient  groups  of  strata,  and  were 
believed  by  Logan  to  be  older  than  these.  In  either  case, 
his  argument  was  the  same :  in  the  former,  these  Ordo- 
vician strata  were  Potsdam  beds  passing  beneath  the  un- 
altered Quebec  group ;  and  in  the  latter,  they  were  the 
same  beds  underlying  the  altered  strata  of  the  same  Quebec 
group. 

§  125.  To  complete  this  history,  we  must  recall  the 
fact  that,  not  conicut  with  including  in  the  newly  organ- 
ized Quebec  group,  besides  the  Cambriiin  Gray  wacke  with 
its  limestones,  the  Taconian  and  the  Huronian  of  the 
Atlantic  belt,  Logan  proposed  to  extend  it  to  Lake  Su})e- 
rior.  Assuming  that  the  horizontal  sandstones  there  over- 
lying  unconformably  the  Keweenian  or  Copper-bearing 


ay. 


LXI. 


XL] 


THE  KEWEENIAN   SERIES. 


Gil 


•ibed  by  Ern- 
ie higber  and 
T  disappeared, 
^  other  than 
,tered  and  so- 
jording  to  bis 
se  sandstones, 
le  Notre  Dame 
.untains)  were 
"  long  after  it 
it  fragments  of 
erates  with  the 
jar  Quebec. 
J  sandstone  was 
tywacke-belt,  to 
J,  these  were  by 
,les  of  the  Levis 
,,     But  this  was 
lirough  inverted 
ons,  came  to  be 
)rdovician  slates, 
irian  or  with  the 
accidents,  made 
strata,  and  were 
In  either  case, 
■mer,  these  Ordo- 
g  beneath  the  uu- 
[er,  they  were  the 
£  the  same  Quebec 

must  recall  the 
I  the  newly  organ- 
|n  Gray  wacke  with 

Huronian  of  the 
id  it  to  Lake  Supe- 
[dstones  there  over- 

lor  Copper-bearuig 


series,  were  of  the  age  of  the  Chazy  or  St.  Peter's  sand- 
stone of  the  upper  Mississippi,  Logan  was  led,  in  1861,  to 
assign  tlie  whole  of  this  series  of  20,000  feet  or  moie  to 
the  Quebec  group,  and  thus  to  give  it  a  position  above 
the  horizon  of  the  fossiliferous  Potsdam  sandstone  of  Wis- 
consin and  Minnesota ;  which,  as  seen  on  the  St.  Croix 
River,  and  elsewhere  in  that  region,  is  well  known  to 
overlie  the  Keweeniau  unconformably,  and  is  probably 
separated  from  it  by  a  great  interval  of  time.  This  view 
will  be  found  represented  on  Logan's  small  map  of  Canada, 
dated  1864,  and  also  in  his  larger  map  of  1866.  The  great 
Animilde  or  Tac(jniau  series, —  the  relations  of  which  in 
this  region  we  have  considered  in  §§  89-90,  and  which  had 
been  previously  described  by  Logan  as  the  lower  division 
of  his  Upper  Copper-bearing  series,  —  was  not  distinguished 
from  it  on  the  maps  in  question,  but  was  now  supposed 
to  represent  the  Potsdam. 

§  125  A.  [As  to  the  history  of  our  knowledge  of  the 
Upper  Copper-bearing  or  Keweenian  series  of  Lake  Su- 
perior, it  was  by  Houghton,  in  1841,  regarded  as  more 
ancient  than  the  Potsdam,  and  by  Logan,  in  1846,  as  in- 
ferior to  the  horizontal  sandstones  of  Sault  Ste.  Marie,  then 
supposed  by  him  to  be  Potsdam.  Logan,  in  the  report  of 
the  geological  survey  of  Canada  for  that  year,  included, 
under  the  name  of  "Volcanic  formations,"  two  divisions, 
a  lower  one  of  dark-colored  argillites  and  quartzites, 
which  is  seen  in  a  nearly  horizontal  attitude  on  Thun- 
der Bay  (where  it  was  afterwards  called  the  Animikie 
series  by  the  present  writer),  and  an  upper  division  of 
sandstones,  amygda^oids,  and  trappean  rocks,  regarded  by 
Logan  as  equivalent  to  the  series  bearing  native  copper  on 
the  south  shore,  and  elsewhere  on  the  lake.  Beneath  this 
lower  division  on  Thunder  Bay  were  older  crystalline 
rocks,  then  described  as  greenstones  with  epidotic  rocks 
and  chloritic  slates,  and  noticed  by  Logan,  in  his  report 
for  1846,  as  the  "chloritic  schists  at  the  suuiniit  of  the 
older  rocks  upon  which  the  Volcanic  formations  rest  un- 


^:% 


,;'ii 


V'  41    j^ 


v,l 


rmff 


<B 


t. 


C12 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


conformably,"  *  the  lower  division  of  the  latter  inoludiag, 
in  a  conglomerate  layer,  portions  of  these  older  rocks. 

§  125  B.  [Two  years  later,  however,  in  his  report  for 
1848,  Logan,  overlooking  these  stratigraphical  relations, 
and  led  by  certain  considerations  set  forth  in  that  report, 
attempted  to  establish  a  parr  Uel  between  the  ancient 
greenstone  and  chloritic  group  and  the  so-called  Volcanic 
formations,  considering  "their  positive  or  appi'oxiinate 
equivalence  highly  probable,  if  not  almost  certain."  Much 
stress  was  then  laid  by  him  on  the  fact  that  the  gi-eenstone 
and  chloritic  series  on  the  north  shore  of  Lake  Huron 
(extending  nearly  to  Sault  Ste.  Marie,  and  often  contain- 
ii./  sulphuretted  copper-ores),  and  the  inclined  sandstone 
and  amygdaloid  series  of  Lake  Superior  carrying  native 
copper,  were  alike  found  resting  unconformably  upon  an 
ancient  granitic  series,  and  unconformably  overlaid  by 
similar  horizontal  sandstones,  then  considered  the  equiva- 
lent of  the  New  York  Potsdam.  The  fact  that  what  was 
regarded  by  him  as  the  amygdaloid  and  trappean  series  had 
beneath  it,  on  Thunder  Bay,  the  dark-colored  argillites  and 
quartzites,  which  in  their  turn  rested  unconformably  upon 
a  greenstone  ana  chloritic  series  like  that  of  Lake  Huron, 
was  strangely  overlooked.  This  new  thesis  of  Logan 
was  adopted  by  Rivot  in  1855  and  1856,  and  by  J.  W. 
Dawson  in  1857,  Rivot  e^en  supposing  that  what  had 
been  regarded  as  igneous  rocks  in  the  amygdaloid  and 
trappean  series  were  but  sediments  altered  in  place. 

§  125  C.    [This  view  of  the  equivalence  of  the  two 

*  The  report8  of  the  Canadian  survey  for  1845  ( on  the  Ottawa  val- 
ley) and  for  1846  (on  Lake  Superior)  were  not  published  until  1847.  In 
February  of  the  latter  year,  the  writer  ccmmenced  his  labors  at  Montreal 
as  chemist  and  mineralogist  to  the  geological  survey  of  Canada,  and,  the 
publication  of  these  reports  having  been  delayed,  he  was  thus  enabled  to 
examine  and  describe  the  various  rocks  and  minerals  from  the  region  of 
tlie  Ottawa,  as  well  as  those  from  Lake  Superior,  '  For  the  lithological 
and  mineralogical  notes  and  descriptions  which  occur  in  the  reports  for 
1845  and  1846,  and  in  the  subsequent  publications  of  the  survey  during 
twenty-five  years,  the  present  M'riter  is  responsible,  inasmuch  as  tliey 
were  all  written  by  him  or  under  his  supervision."    Azoic  Kocks,  p.  66. 


',Y. 


XI.] 


THE   KEWEENJAN  SERIES. 


613 


ter  includiag, 
der  rocks. 
.lis  report  for 
ical  relations, 
n  that  report, 
X  the   ancient 
ailed  Volcanic 
r  approximate 
jrtain."    Much 
the  greenstone 
,f  Lake  Huron 
[  often  contain- 
iined  sandstone 
carrying  native 
rmably  upon  an 
bly  overlaid  by 
ered  the  equiva- 
jt  that  what  was 
ippean  series  had 
red  argillites  and 
onformably  upon 
c  of  Lake  Huron, 

thesis  of   Logaii 

6,  and  by  J-  W. 
that  what  had 
amygdaloid  and 

3d  in  place. 

lence  of  the  two 

5  (on  the  Ottawa  val- 
,Ushed  until  1847.  In 
his  labors  at  Montreal 

ev  of  Canada,  and,  the 
he  was  thus  enabled  to 

rals  from  tbe  region  o 
'Forthelithological 

•cur  in  the  reports  for 
s  of  the  survey  during 
ble,  inasmuch  as  they 
Azoic  Rocks,  p.  oo- 


unlike  series  was  disputed  in  1857  by  J.  D.  Whitney,  who 
maintained  the  distinctness  of  the  greenstone  and  chloritic 
group  from  the  cupriferous  amygdaloid  and  trappean 
series  of  the  south  shore  of  the  lake,  and  at  the  same 
time  asserted  that  the  latter  "  cannot  be  separated  from 
the  Potsdam  sandstone  witli  which  it  is  associated ;  neither 
is  there  any  reason  whatever  for  placing  it  in  the  same 
line  with  the  rocks  of  the  north  shore  of  Lake  Huron." 
In  the  "  Geology  of  Canada "  in  1863,  Logan  returned 
to  his  former  view  of  the  distinctness  of  the  greenstone 
and  chloritic  group  (which,  from  its  sulphuretted  copper- 
ores,  he  sometimes  called  the  Lower  Copper-bearing 
group),  to  which,  in  1855,  the  present  writer  had  given 
the  name  of  Huronian.  Logan  now  described  this  as 
*' unconformably  overlaid  by  a  second  series  of  copper- 
bearing  rocks,"  designated  by  him  as  the  Upper  Copper- 
bearing  series,  and  including  the  two  divisions  of  his 
Volcanic  formations  already  distinguished  in  1846.  This 
second  series,  he  however  declared,  in  opposition  to  Whit- 
ney, to  be  distinct  from  the  nearly  horizontal  sandstones 
of  the  east  end  of  the  lake,  which  he  sui)posed,  with 
Houghton,  to  overlie  unconformably  the  Upper  Copper- 
bearing  series.  Already,  however,  in  1861,  Logan  had 
conceived  the  notion  tliat  this  series  might  be  the  strati- 
graphical  equivalent  of  the  First  Gray  wacke  or  Upper  Ta- 
conic,  to  which  he  had  given  the  name  of  the  Quebec 
group.  The  Animikie  or  lower  division  of  liis  Volcanic 
formations,  which  is  often  absent  (the  upper  division  rest- 
ing directly  on  the  Huronian  or  the  ancient  gneiss),  was 
henceforth  called  Potsdam,  and  the  overlying  sandstone, 
now  known  to  be  Cambrian  of  the  Potsdam  period,  was 
supposed  by  Logan  to  be  the  equivalent  of  the  St.  Peter 
or  Chazy  sandstone,  and  thus  of  Ordovician  age. 

§  125  D.  [Notwithstanding  all  this  discussion,  and  the 
conclusions  of  Whitney  and  Logan,  sustained  by  Kimball 
in  1865,  as  to  the  distinctness  of  the  Huronian  from  the 
overlying  Upper  Copper-bearing  series,  Brooks  and  Pum- 


'il 


.1.    !- 


n* 


vm 


i.i  I 


::| 


614 


THE  TACOl.IC  QUESTION  IN   GEOLOGY. 


[XI. 


pelly,  in  1873,  expressed  the  opi:  'on  that  the  latter  was 
"formed  before  the  tilting  o^i  the  Huronian  beds,  upon 
which  it  rests  conformably."  It  rerap.ins  to  be  decided 
whetlier  this  observation  refers  to  the  true  Huronian  or  to 
the  younger  Taconian  series,  so  often  hitherto  confounded 
therewith,  which  itsolf  is  unconformable  with  the  Hu- 
ronian. The  presence,  already  noticed  by  Thomas  Mac- 
farhiiie  and  myself,  of  boulders  of  crystalline  rock  in  the 
conglomerates  of  the  Upper  Copper-bearing  series,  notably 
at  Mamainse,  where  I  had  observed  such  masses  having 
the  characters  alike  of  the  Laurentian,  Huronian,  and 
Montalbiin  series,  was  evidence  of  a  great  stratigraphical 
break  between  these  and  the  former,  and  I  was  led  to 
suppose  that  the  same  sub-aerial  decay  which  had  fur- 
nished these  boulders  had  liberated  the  copper  found  in 
a  metallic  state  in  the  younger  rocks.  Hence,  conceiv- 
ing the  stratigraphical  distinctness  of  the  Upper  Cop- 
per-bearing series,  alike  from  the  Huronian,  from  the 
Potsdam,  and  from  the  so-called  Quebec  group,  to.  be 
unquestioned,  I  ventured  to  propose  for  it,  in  1873,  the 
name  of  the  Keweenaw  group.  Two  years  later,  in  1875, 
Brooks,  having  arrived  at  a  similar  conclusion,  declared 
these  rocks  to  constitute  "a  distinct  and  independent 
series,  marking  a  definite  geological  period,"  and  proposed 
as  a  designation  the  adjective  Keweenawian.  For  this, 
the  writer,  in  1876,  while  recalling  his  own  conclusions, 
and  the  name  of  Keweenaw  series,  already  given  by  him, 
suggested  the  more  euphonious  adjective  Keweenian. 

[This  is  to  be  understood  as  marking  a  period  distin- 
guished by  the  deposition  of  a  great  thickness  of  uncrys- 
talline  sediments,  and  separated,  in  the  Lake  Superior 
region,  by  stratigraphical  breaks  alike  from  the  overlying 
Cambrian  (Potsdam)  and  the  various  underlying  crystal- 
line series  from  the  Laurentian  to  the  Taconian  inclusive, 
upon  each  of  which  it  may  repose  in  turn.  We  shall 
notice  farther  on  its  probable  relations  to  the  Grand 
Canon  group  of  Arizona,  and  the  Llano  group  of  Texa?,  us 


XL] 


AMERICAN   PALEOZOIC   HISTORY. 


615 


suggested  by  Walcott.  Meanwhile  it  is  to  be  remarked 
that  the  Keweeuian,  on  Lake  Superior,  affords  apparent 
traces  of  organisms.  I  quote  from  a  description  in  1878  in 
"Azoic  Rocks,"  p.  237:  There  are  certain  markings  in  the 
Keweenian  which  are  probably  of  organic  origin.  Logan, 
in  1847,  described  the  occurrence  in  some  of  the  earthy 
or  so-called  tufaceous  beds  of  the  series,  of  numerous  slen- 
der vertical  tubes,  filled  with  calcite,  having  a  diameter  of 
about  a  quarter  of  an  inch,  and  a  length,  in  some  cases,  of 
from  eight  to  twelve  inches.  Two  or  iiiore  of  these  tubes 
were  often  found  to  coalesce  in  ascending,  and  they  were 
supposed  by  Logan  to  have  been  formed  by  currents  of 
gas  rising  through  a  pasty  mass  ("  Geology  of  Canada," 
p.  71).  From  the  observations  of  the  writer,  in  1872,  on 
Michipicoten  Island,  where  similar  markings  were  found 
in  an  argillaceous  stratum,  he  was  led  to  compare  them 
with  some  forms  of  so-called  Scolithus,  and  to  regard 
them  as  due  to  the  burrowing  of  annelids.  These  were 
accompanied  by  large  numbers  of  two  curious  forms,  the 
one  club-shaped,  and  the  other  hemispherical  ^v  dome- 
shaped;  each  recalling  some  sponges.  These,  I  ke  the 
tubes,  were  filled  with  calcite,  agate,  or  crystalline 
quartz,  and  sometimes  in  part  with  a  greenish  chloritic 
mineral.] 

VII.  —  PALEOZOIC  HISTORY  OF  EASTERN  NORTH  AMERICA. 

§  126.  To  render  more  intelligiblp  the  relations  of  the 
Taconian,  Cambrian,  Ordovician,  and  Silurian  rocks  of 
eastern  North  America  to  each  other,  and  to  the  older 
Pri  vary  rocks,  we  shall  endeavor  to  present  a  sketch  of 
the  geological  history  of  the  region,  based  upon  the 
facts  already  set  forth.  At  the  beginning  of  Cambrian 
time,  marked  by  the  earliest  known  trilobitic  fauna,  there 
stretched  along  the  eastern  border  of  the  great  paleozoic 
basin,  a  wide  area  of  crystalline  eozoic  rocks ;  the  remains 
of  which  are  now  seen  in  the  Blue  Ridge,  and  its  eastern 
slope,   from   Akbama  to  Virginia,  and  in   their  north- 


'  S'  ii 

i 

iM 

!          1 

■          I 

''1    u 


aL.k ; 


'till 


616 


THE  TACONIC   QUESTION  IN  GEOLOGY. 


tXI. 


eastern  prolongation  through  the  South  Mountain  of 
Pennsylvania,  the  Highlands  of  tlie  Hudson,  the  crystal- 
line rocks  of  NeAV  England  and  of  the  whole  region  of 
Canada  south  and  east  of  the  lower  St.  Lawrence.  To 
the  north  of  the  great  paleozoic  basin  was  a  similar  eozoic 
area,  now  represented  by  the  Laurentides,  stretching 
westward  to  liie  upper  Mississippi,  and  beyond,  and 
connected  by  low-l3ung  portions  with  the  insular  mass  of 
the  Adirondacks.  The  evidences  of  similar  eozoic  islands 
are  seen  in  parts  of  Newfoundland,  northern  Michigan, 
Wisconsin,  Dakota,  Missouri,  Texas,  etc.  These  eozoic 
lands,  alike  on  the  western,  on  the  northci-n,  and  on  the 
eastern  shores  of  this  early  Cambrian  sea,  presented  then, 
as  now,  portions  of  several  great  terranes,  or  series  of 
crystalline  stratified  rocks,  lying  unconformably  upon 
one  another,  or  upon  a  more  ancient  gneissic  floor,  and 
telling  a  long  history  of  successive  depositions,  elevations, 
and  depressions,  sub-aerial  decay  and  erosion.  These 
various  groujjs  we  have  briefly  noticed  in  the  second 
chapter  of  this  essay.     (§  18.) 

§  127.  The  local  geographical  conditions  presented  by 
different  portions  of  northeastern  America  during  the 
long  period  when  the  depression  of  parts  of  the  pre- 
Cambrian  land  permitted  the  deposition  over  its  surface 
of  Cambrian,  Ordovician,  and  Silurian  sediments,  next 
demand  our  attention.  Eaton  had  already,  previous  to 
1832,  divined  that  the  Calciferous  Sand-rock  (whicli, 
underlying  the  Metalliferous  or  Trenton  limestone,  rests 
directly  upon  the  Primitive  gneiss)  along  the  western 
shore  of  Lake  Champlain,  occupies  the  stratigraphical 
horizon  of  the  Sparry  Lime-rock  found  farther  eastward, 
at  the  summit  of  the  First  Graywacke ;  and  consequently 
that  this  great  mass  of  strata,  as  well  as  the  more  ancient 
Transition  Argillite,  and  the  Primitive  Lime-rock  and 
Quartz-rock,  was  absent  along  the  western  side  of  the 
lake.  Emmons,  in  1846,  sought  to  explain  this  deficiency, 
so  far  as  the  First  Graywacke  was  concerned,  by  main- 


XI.l 


AlVrERICAN   PALEOZOIC   HISTORY. 


617 


taining  tliat  tliis  great  group  of  strata,  togetlier  with  its 
overl3'ing  Sparry  Lime-rock,  is  really  the  representative, 
or,  as  he  expressed  it,  is  "  a  protean  devek)pment "  of  the 
Calciferous  Sand-rock.  In  other  words,  this  magnesian 
limestone,  having,  according  to  him,  a  maximum  thick- 
ness of  300  feet  between  the  Trenton  or  Chazy  limestone 
and  the  underlying  gneiss,  on  the  west  side  of  Lake  Cham- 
plain,  Avas  represented  to  the  eastward,  along  tiie  west- 
ern base  of  the  belt  of  Primitive  rocks,  in  New  York,  New 
England,  and  Quebec,  by  a  vast  accumulation  of  sand- 
stones, conglomerates,  argillites,  and  limestones,  to  which 
he  assigned  a  thickness  of  not  less  than  25,000  feet.  Sub- 
sequently, in  1855,  he  supposed  that  portion  of  this  great 
series  which  had  been  known  as  the  Red  Sand-rock  of  Ver- 
mont, to  be  the  representative  of  the  Potsdam  sandstone ; 
which  latter  he  had  jn-eviously  found  to  underlie,  in  some 
p;;rts  on  the  west  side  of  the  lake,  the  Calciferous  Sand- 
rock  of  his  Champlain  division. 

§  128.  These  conclusions  of  Emmons  as  to  the  strati- 
graphical  relations  of  the  First  Graywacke  —  called  by 
him  Upper  Taconic  —  to  the  New  York  paleozoic  system, 
were,  as  we  have  seen,  adopted,  in  18G1,  by  the  officers  of 
the  geological  survey  of  Canada;  who  then  gave  to  the 
Graywacke  series  the  name  of  the  Quebec  group,  and 
maintained,  on  paleontological  grounds,  that  it  might  also 
represent  the  Chazy  limestone,  and  thus  con-espond  to  the 
period  between  the  Trenton  limestone  and  the  Potsdam 
sandstone.  It  was  evident  that  these  great  differences  of 
thickness,  and  in  lithological  characters,  between  the 
equivalent  rocks  in  the  two  areas  above  referred  to,  must 
have  been  the  result  of  widely  unlike  geographical  condi- 
tions in  the  adjacent  regions.  Along  the  eastern  border 
of  the  Cambrian  sea,  great  subsidence  and  frequent 
changes  permitted  the  deposition  of  a  series  of  sediments 
variously  estimated  at  from  10,000  to  25,000  feet  in  thick- 
ness, presenting  an  abundant  and  diversified  fauna,  with* 
great  variations  in  mineral  character,  often  due  in  part 


;i.!. 


I'       'i: 


I  iSSIil.;:: 


G18 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


to  the  materials  derived  from  the  contiguous  Huronian, 
Muntalban,  and  Taconian  rocks. 

§  129.    Meanwhile,  it  is  apjiarent  that  over  the  more 
btable  areas  to  the  westward,  along  the  base  of  the  Adiron- 
dack?  md  br-rvec  1  these  mountains  and  the  Laurentides 
to  the      ri  .,  uhere  was,  during  a  great  part  of  the  period, 
dry  laii  i. .  ;io-i    ubsequently  a  region  of  shallow  water,  in 
which  th      ,ii^  je'Uments  were  the  silicious  sands  derived 
from  the  adjacent   .  urentian,  or  perhaps  Taconian  rocks; 
giving  rise  to  the  Potsdam  sandstone,  with   its  ri2)ple- 
marks,  its  tracks  of  crustaceans,  and  its  very  scanty  fauna. 
To  this  succeeded  lagoons  in  which  were  deposited  the 
dolomites  of  the  so-called  Calciferous  Sand-rock,  holding 
bitterns,  and  occasionally  gypsum.     This  deposit  rests,  in 
some  parts,  on'  the  sandstone,  and  in  others  directly  upon 
the   ancient  gneiss.     The  united  thickness  of  the  infra- 
Trenton    members    of    the   Champlain   division  in   this 
region,  even  including  the  Chazy  limestone,  to  be  men- 
tioned below,  will  not  exceed  1000  feet,  and  is  generally 
much  less.     The  time  occupied  in  the  deposition  of  these, 
however,  was  but  a  small  portion  of  the  great  Cambrian 
period.     The  so-called  Lower  Potsdam  beds  of  the  latter, 
from  Troy  to  Newfoundland,  not  to  mention  the  still  more 
ancient  Menevian  (Paradoxides)  beds  of  eastern  Massa- 
chusetts, southern  New  Brunswick,  and  Newfoundland  — 
are  known  by  paleontologists  to  mark  an  earlier  period 
than  the  typical  Potsdam  of  the  Champlain  and  Ottawa 
basins.     The  fauna  of  the   Levis   limestone,  which  was 
Eaton's   Sparry   Lime-rock,  according   to   Billings  (who 
rightly  regarded  it  as  the  summit  of  the  Quebec  group), 
belongs  to  a  horizon  superior  to  that  of  the  typical  Calcif- 
erous Sand-rock.      From  all  of  these  facts  we  conclude 
that  the  original  Potsdam   and  Calciferous  subdivisions 
are  but  local'and  partial  representatives,  alike  clironologi- 
cally  and  paleontologically,  of  the  great  Cambrian  Gray- 
wacke   period,   anterior  to   the   time    of   the   deposition 
of  the   Ordovician   (Trenton)    limestones.      [See  for  a 


XL] 


AMERICAN  PALEOZOIC   IIISTOUY. 


619 


more  recent  discussion  of  the  American  Cambrian  strata 
§§  127  A-127  B.] 

§  130.  The  fauna  of  the  intermediate  and  non-mag- 
nesian  Cliazy  limestone,  as  has  been  shown  by  Billings, 
serves  to  connect  that  of  the  Levis  limestone  with  the 
fauna  of  the  Trenton.  This  Chazy  limestone  is  absent  in 
some  localities  in  central  New  York,  where,  according  to 
Hall,  the  Trenton  rests  directly  upon  the  Calciferous,  as 
it  does  elsewhere,  in  the  absence,  of  this,  upon  pre-Cam- 
brian  rocks.  The  deposition  of  the  Chazy  in  the  Otta^ 
valley  is  distinctly  marked  as  a  period  of  disturbance 
since  it  presents  at  its  base  a  limestone-conglomer  e, 
resting  on  the  Calciferous,  and  followed  by  about  ft^ 
fef)t  of  sandstones  and  shales ;  to  which  succeed  t*  • 
fossiliferous  beds  of  pure  limestone,  sometimes  with 
dolomitic  layers,  which  constitute  the  typical  Ch  Lit 
the  Ottawa  basin.*  The  above  facts  with  regard  to  the 
Chazy  are  additional  evidences  of  the  period  of  distur- 
bance which,  as  already  set  forth,  marked  the  close  of  the 
Cambrian  period,  and  brought  in  the  Ordovician.  The 
continental  movements  of  that  time,  while  they  plicated 
and  uplifted  the  previously  deposited  fossiliferous  strata 
along  the  southeastern  border  of  the  Cambrian  area, 
caused  elsewhere  a  subsidence  which  allowed  the  Ordo- 
vician sea  to  spread  far  and  wide  to  the  north,  depositing 
its  nearly  pure  limestones,  with  a  thickness  of  600  feet  or 
more,  along  the  St.  Lawrence  valley,  not  only  over  the 
Cambrian  beds,  but  over  the  eozoic  land. 

§  131.  To  the  south  and  east,  however,  the  uplifted 
and  eroded  Cambrian  strata,  with  their  adjacent  eozoic 
rocks,  the  Taconian  included,  formed  the  eastern  shores 
of  the  Ordovician  sea,  approaching  which,  as  we  have 
already  seen  (§  111),  the  massive  limestones  of  that 
period  become  thinner  and  disappear;  being  apparently 
replaced  by  the  black  shaly  beds,  which,  at  various  points, 
are  found  lying  among  the  older  rocks.  How  far  the 
*  Azoic  Rocks,  pp.  124,  13e. 


!  :li 


^r 


;^l  I 

1  •*     i; 


■\ 


H 


620 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


subsequent  movement  —  which,  as  has  been  shown,  dis- 
turbed and  eroded  the  Trenton  limestone  in  the  Ottawa 
valley  before  the  deposition  of  the  Loraine  shale  (§  110) 
—  was  felt  in  this  eastern  region,  is  uncertain.  It  is  also 
a  question  how  far  the  higher  strata,  known  as  the  Oneida 
sandstone,  were  laid  down  in  this  region  over  the 
Loraine  shale.  This  latter  is  found  preserved  from  de- 
nudation in  regions  to  the  east  of  Lake  Champlain,  along 
the  lines  of  dislocation  which  have  brought  up  on  its  east- 
ern side  the  underlying  Cambrian  strata;  and  it  is  not 
improbable  that  portions  of  the  upper  sandstone  of  the 
Second  Graywacke  may,  as  some  have  supposed,  there  be 
found  in  the  vicinity  of  the  First  Graywacke. 

§  132.  We  have  already  noticed  the  subsequent  inva- 
sion of  the  Silurian  sea,  depositing  its  limestones  over  the 
lower  levels  from  central  New  York  northward  and  east- 
ward as  far  as  Gasp6  and  Newfoundland.  Thus  it 
happens  that  we  find  portions  of  these  limestones  over- 
lying alike  Ordovician,  Cambrian,  Taconian,  and  still 
older  strata,  and  involved  with  all  of  these  by  subsequent 
movements  of  the  strata.  As  a  result  of  tiiese  geological 
accidents,  successive  observers  have  been  led  into  many 
errors.  Thus,  the  Taconian  marbles  have,  within  the 
last  generation,  been,  by  different  geologists,  declared  to 
be  of  Cambrian,  of  Ordovician,  of  Silurian,  and  even  of 
Devonian  age ;  while  similar  views  have  been  maintained 
with  regard  to  the  geological  horizon  of  the  still  older 
crystalline  schists  of  the  region,  of  which  we  have  already 
given  examples  (§§  121,  123). 

§  133,  The  statement  which  has  been  made,  and  often 
repeated,  that  in  Cambrian  and  Ordovician  times  the 
rocks  of  the  Green  Mountains  were  laid  down  as  sedi- 
ments beneath  the  sea,  and  that  at  the  close  of  this  latter 
period,  these  were  hardened,  crystallized,  and  uplifted  as 
a  mountain-range,  is  seen,  from  what  has  been  set  forth, 
to  be  a  fiction  based  upon  the  hypothesis,  first  clearly 
formulated  by  Mather,  and  repeated  by  his  successors, 


XI.] 


AMEIUCAN    rALKOZOIC   HISTOUY. 


021 


(including,  during  many  years,  the  present  writer),  that 
the  rocks  of  this  mountain-range  are  altered  paleozoic 
strata.  Of  this  there  is  no  evidence,  while,  on  the  con- 
trar}',  the  relations  of  the  paleo  c  strata  to  these  crystal- 
line rocks  throughout  the  Atlantic  belt,  and  the  })resence 
of  fragments  of  these  in  the  paleozoic  conglomerates, 
demonstrate  their  greater  antiquity.  The  same  consider- 
ations apply,  a  fortiori^  to  the  similar  hypothesis  of  the 
crystallization,  folding,  and  uplifting  of  Silurian  and 
Devonian  rocks  at  the  close  of  paleozoic  time,  to  form 
the  White  Mountain  range. 

§  134.  Ihe  Wiiito  Moui^tains,  the  Green  Mountains, 
the  Taconic  Hills,  the  Highland  range,  and  in  fact,  all 
the  crystalline  stratified  rocks  of  the  Atlant'c  region,  are 
parts  of  the  great  eozoic  land  which  bounded,  to  the 
south  and  east,  the  Cambrian  sea  of  North  America.  The 
same  groups  of  rocks  then,  as  now,  moreover,  stretched 
along  the  northern  and  western  borders  of  that  vast  sea, 
which  deposited  its  sediments  alike  over  them  all. 

[Considerations  set  forth  farther  on,  in  §  137  B,  show 
that  the  Keweenian  rocks  of  Lake  Supeiior,  and  the 
similar  strata  beneath  the  Cambrian  in  central  Texas  and 
in  Arizona,  mark  a  period  in  which,  over  the  more 
western  portions  of  our  continent,  a  vast  accumulation  of 
sediments  took  place  between  the  time  of  the  Taconian 
and  that  of  the  deposition  of  the  Upper  Cambrian.  These 
Keweenian  sediments,  though  so  far  as  we  know  distinct 
from  the  Cambrian,  are,  by  their  un crystalline  character, 
more  closely  related  to  it  than  to  the  Taconian.] 

§  135.  The  successive  movements  of  the  earth's  crust, 
with  foldings,  often  with  inversions  and  with  dislocations, 
which  have  at  intervals  affected  the  paleozoic  rocks  in 
the  eastern  portion  of  this  great  basin,  in  proximity  to  the 
Atlantic  belt,  throughout  its  entire  length,  have,  it  is  true, 
been  attended  with  uplifts  of  the  strata  on  the  eastern 
side  of  the  dislocations;  which  have,  to  some  extent, 
compensated  for  the  loss  of  substance  £rom  these  ancient 


•'Ml' I 


k^ 


622 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


i!' 


crystalline  roclca  by  sub-acrial  decay  and  erosion.  These 
movements,  us  we  have  had  occasion  to  sliow  in  the  pre- 
ceeding  pages,  have  in  many  cases  involved  in  their  folds 
the  superincumbent  paleozoic  strata,  thus  giving  rise  to  a 
deceptive  appearance  of  infraposition  of  these  newer 
rocks.  The  fractures  which  often  accompany  these 
folds  still  afford  passage,  in  some  cases,  to  thermal 
waters;  and  such  waters,  in  past  times,  by  their  action 
upon  the  strata  along  their  course,  have  produced  local 
changes,  by  the  development  of  crystalline  minerals ;  a 
phenomenon  which  has  been  invoked  in  support  of  the 
paleozoic  age  of  the  crystalline  schists.  The  discussion 
of  the  evidences  of  this,  and  of  various  questions  which 
arise  in  this  connection,  as  well  as  that  of  the  different 
hypotheses  which  have  been  put  forth  with  regard  to  the 
age  of  the  Taconian  rocks,  will  be  tak  n  up  in  succeeding 
chapters. 

VIIT.  —  THE  TACONIC  HISTORY  REVIEWED. 

§  186.  In  reviewing  the  preceding  account  of  the 
Taconic  question  it  is  proposed  to  notice,  in  the  first 
place,  some  of  the  characteristic  differences  of  the  Cam- 
brian Of  Upper  Taconic  rocks  as  seen  in  different  parts  of 
North  America,  to  follow  the  results  of  paleontological 
investigation  from  thte  distuibed  region  in  eastern  Canada 
southward  into  Vermont  and  New  York,  and  thus  to 
prepare  the  way  for  a  consideration  of  the  varying  and 
contradictory  hypotheses  which  have  been  from  time  to 
time  put  forth  as  to  the  age  of  both  the  Upper  and  Lower 
Taconic  series. 

§  137.  The  Cambrian  rocks  of  New  York,  as  originally 
described  by  its  geological  survey,  were  known  only  in 
the  stable  and  little  disturbed  region  around  the  Adiron- 
dack Mountains,  including  the  area  west  of  Lake  Cham- 
plain  and  a  part  of  the  Ottawa  basin,  where  the  series  is 
represented  by  the  qiiartzites  and  magnesian  limestones 
of  the  Potsdam  and  Calciferous  subdivisions,  which  are 


XI.] 


THE  TACONIC    HISTORY    REVIEWED. 


C23 


sliiillow-wnter  doposits,  corresponding,  apparently,  to 
snmll  portions  only  of  Canihriaii  time.  The  conditions 
of  the  Mississippi  area  are  similar  to  those  of  the  Adiron- 
dack region.  In  Wisconsin,  where  the  Potsdam  beds 
rest  in  a  nearly  horizontal  position  npon  highly  distnrbed 
strata,  often  of  Keweenian  age,  these  sandstones  and  mag- 
nesian  limestones  of  the  Cambrian,  lying  in  nndistnrbed 
succession,  have  about  1000  feet  in  thickness,  and  are 
overlaid  by  the  St.  Peter  sandste'"^,  which  divides  them 
from  ♦he  succeeding  Trenton,  and  may  itself  be  regarded 
as  the  base  of  the  Ordovician.  When,  however,  we 
reach  the  (yordilleras,  we  find  a  great  augmentation  in 
the  thickness  of  th^se  lower  rocks.  In  the  Eureka  dis- 
trict of  Nevada,  according  to  the  late  studies  of  Arnold 
Hague  and  Walcott,  the  fauna  of  the  so-called  Lower 
and  Upper  Potsdam  ranges  through  more  than  7000  feet 
of  strata,  and  is  succeeded  by  that  of  the  Chazy  and  Tren- 
ton subdivisions. 

I  137  A.  [In  the  Wasatch  range  in  Utah  there  are 
known  to  be  not  less  than  12,000 -feet  of  conformable 
Cambrian  strata,  wliile  in  the  Eureka  district  of  Nevada 
7700  feet  have  been  observed,  there  overlaid  by  Ordo- 
vician, and  including  at  their  base  1700  feet  of  the  upper 
part  of  the  Wasatch  section,  so  that  by  combining  these 
two  sections  we  have  in  the  great  American  basin  not 
less  than  18,000  feet  of  fossiliferous  Cainbrian  rocks.  Wal- 
cott, who  has  carefully  studied  the  very  extcr  sive  fauna  of 
this  central  region,  and  has  compared  il,  w'th  that  of  the 
east,  divides  the  American  Cambrian  into  three  parts. 
The  Lower  Camlnan,  as  far  as  )'et  known,  is  confined  to 
the  Atlantic  coast .  and  represented  by  the  small  areas  in 
Massachusetts,  New  Brunswick,  and  the  island  of  New- 
foundland, being  the  St.  John's  group  of  Ilartt  and  Bill- 
ings, which  we  have  in  the  present  essay  spoken  of  as 
Menevian,  and  which,  including  the  Menevian  horizon  of 
Wales,  corresponds  to  the  lowest  Cambrian  of  Europe. 

[The  Cambriun  i.'cks  within  our  great  continental  area 


:".H. 


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THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


aie  by  Wulcott  iuclucled  in  his  middle  and  upper  divis- 
ions. Tlie  first  of  these  is  the  so-called  Lower  Potsdam 
of  Billings,  which  is  traced  from  the  strait  of  Bellisle 
along  the  valleys  of  the  St.  Lawrence,  Lake  Cham- 
plain,  and  the  Hudson,  and  thence  southward  along  the 
great  Appalachian  valley,  embracing  a  large  part  of  tlie 
Upper  Taconic  of  Emmons.  The  upper  division  of 
the  Cambrian  includes  the  typical  Potsdam  of  the  Adir- 
ondack area  and  of  the  upper  Mississippi  valley,  in  both 
of  which  regions  the  Middle  Cambrian  is  unknown.  The 
Middle  and  Upper  Cambrian  appear  together  in  the  sec- 
tions in  Utah  and  Nevada,  where  the  latter  is  succeeded, 
as  in  the  more  eastern  areas,  by  rocks  carrying  the  second 
fauna  of  Barrande,  which  Walcott,  following  Lapworth 
and  the  present  writer,  designates  as  Ordovician  (§  17). 
This,  it  will  be  remembered,  is  synonymous  with  the 
Lower  Silurian  of  Murchison,  and  with  the  Upper  Cam- 
brian of  Sedgwick,  which  is  thus  distinct  from  and  supe- 
rior to  the  Upper  Cambrian  of  Walcott. 

§  137  B.  [Ill  the  Grand  Canon  of  the  Colorado  River 
1000  feet  of  Upper  Cambrian  ov  Potsdam  strata,  locally 
known  as  the  Tonto  group,  rest  uuconformably  upon  a  great 
body  of  strata  described  by  Powell  as  the  Grand  Canon 
series,  divided  by  him  into  the  Grand  Canon  and  Chuar 
groups,  and  having  an  observed  thickness  of  about 
13,000  feet.*  In  like  manner,  a  series  of  Cambrian  sand- 
stones and  limestones,  about  900  feet  in  thickness,  closely 
resembling  those  of  the  Tonto  group,  and  affording  a 
abundant  Potsdam  fauna,  already  made  known  by  Shu- 
mard,  occur  in  central  Texas,  where  they  are  overlaid  by 
Ordovician.  Here,  as  in  the  Grand  Canon  of  the  Colo- 
rado, the  Upper  Cambrian  strata  rest  unconfcjrniably 
upon  a  series  of  uncrystalline  sandstones,  shales,  and  lime- 
stones, several  thousand  feet  in  thickness,  which  are  well 
seen  in  Llano  county,  and  have  -n  by  Walcott  called 
the  Llano  group.     These,  according   to  him  were  pene- 

,  *  Powell,  Amor.  Jour.  Science,  1883,  xxvi.,  437. 


3GY.  ^^'• 

i  upper  divis- 
ower  Potsdam 
lit  of  BelUsle 
,   Lake   Cham- 
ard  along  the 
i-ge  part  of  the 
)QV   division  of 
im  of  the  Adir- 

valley,  in  both 
unknown.  The 
ither  in  the  sec- 
ter  is  succeeded, 
L-ying  the  second 
>wing  Lapwovth 
dovician  (§  l'^)- 
lymous  with  the 

the  Upper  Cam- 
it  from  and  supe- 

le  Colorado  Hivev 
am  strata,  locally 
..ably  upon  a  great 
Ithe  Grand  Canon 
"anon  and  Chuar 
clcness   of    about 
,f  Cambrian  sand- 
thickness,  closely 
I,  and   affording  a 
.e  known  by  Shu- 
jy  are  overlaid  by 
^anon  of  the  Colo- 
^t    unconformaijly 
E,  shales,  and  lime- 
iss,  which  are  well 
Iby  Walcott  called 
0  him  were  pene- 
Lxvi.,  431. 


XI.] 


THE  TACONIC   HISTORY  KEVIEVVED. 


625 


trated  by  granites  befoie  the  deposition  of  the  Pots- 
dam.* This  great  series  of  uncrystalline  sediments,  found 
alike  in  the  Grand  CaSon  and  in  Texas,  is  by  Walcott 
compared  with  the  Keweenian  series  of  Lake  Superior, 
and  regarded  as  belonging  to  a  Keweenian  area  of  conti- 
nental extent,  over  the  upturned  and  eroded  edges  of 
which  the  Cambrian  was  laid  down  alike  in  Michigan  and 
Minnesota,  in  Texas  and  in  Arizona.  Some  evidences  of 
organic  remains  have  been  observed  by  Walcott  in  these 
lower  rocks  in  the  Grand  CaRon,  and  we  have  elsewhere 
noticed  such  evidences  in  tlie  Keweenian  of  Lake  Superior 
(ante,  page  615).  For  the  present,  we  agree  with  Pow- 
ell and  with  Walcott  in  regarding  these  lower  rocks 
provisionally  as  pre-Cambrian.]  f 

§  138.  A  similar  great  development  of  Cambrian  rocks 
exists  in  mnthwestern  Newfoundland,  where,  from  his 
studies  of  their  organic  remains,  the  late  Mr.  Billings  was 
led  to  admit  a  succession  of  over  9000  feet  of  paleozoic 
strata  below  the  Trenton  horizon.  The  subdivisions  there 
recognized  by  him,  in  ascending  order,  were :  1.  Lower  Pots- 
dam ;  2.  Upper  Potsdam;  3.  Lower  Calciferous;  4.  Upper 
Calciferous ;  5.  Levis ;  and  6.  Phyllograptus  beds.  The 
second  and  third  of  these  were  regarded  by  Billings  as  the 
representatives  of  the  Adirondack  Potsdam  and  Calcifer- 
ous, while  the  Phyllograptus  beds  at  the  summit  were  con- 
sidered the  equivalent  of  the  Welsh  Arenig,  which  belongs 
to  the  base  of  the  Bala  group,  or  the  second  fauna.  It  is 
evident,  as  Billings  declared,  that  we  have,  in  this  great 
thickness  in  northwestern  Newfoundland,  a  nuich  more 
complete  sequence  than  in  the  Adirondack  region,  where 
the  Upper  Potsdam,  Calciferous,  and  Chazy  subdivisions 
represent  the  whole  succession  from  the  ancient  gneiss  up 
to  the  Trenton  limestone. 

•  Walcott,  ibid.,  xxviii.,  431. 

t  For  these  geneiiilizations  by  Walcott  as  to  the  American  Cambrian, 
I  am  Indebted  to  a  yet  unpubiisherl  paper  read  by  him  before  the  National 
Academy  of  Scioiirps  at  Washington,  April  23^  1880,  and  to  his  private 
communicatious. 


¥  I. 


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II 


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626 


THE  TACONIC  QUESTION   IN  GEOLOGY. 


§  139.  Keeping  in  view  the  great  development  of  the 
Cambrian  alike  in  the  Cordilleras  and  in  Newfoundland, 
as  compared  with  the  Cambrian  of  the  Adirondack  and 
Mississippi  areas,  we  are  better  prepared  to  understand  the 
remarkable  type  assumed  by  this  series  in  the  Appalachian 
area,  on  the  eastern  margin  of  the  American  paleozoic 
basin,  from  near  the  Gulf  of  Mexico  northeastward  to  the 
Gulf  of  St.  Lawrence,  and  to  Newfoundland,  along  the  west- 
ern base  of  the  Atlantic  or  Appalachian  belt.  These  Cam- 
brian rocks  throughout  this  extent,  wherever  preserved, 
are  characterized  by  great  thickness  and  considerable 
diversities  in  composition,  due  to  the  acfumulation  of 
mechanical  sediments  <'"rived  from  tlie  di.  integration  and 
decay  of  the  various  groups  of  pre-Cuinbrian  rocks  which 
made  up  the  .-djacent  eozoic  land.  To  this,  and  to  re- 
peated nujvemeuts  of  the  land  during  and  jifter  the  Cam- 
brian period,  they  owe  their  complex  constitution,  their 
great  volume,  tlieir  disturbed  and  faulted  condition,  and 
tlieir  unconformities.  All  of  these  characters  serve  to 
distinguish  them  widely  from  the  horizontal  and  compara- 
tively thin  quartzites  and  magnesian  limestones,  their 
representatives  along  the  northern  border  of  the  great 
basin,  as  seen  in  the  Adirondack  and  Mississippi  areas. 
It  is  this  Appalachian  Cambrian,  many  thousand  feet  in 
thickness,  which,  as  we  have  already  seen,  constitutes  the 
First  Graywacke  and  the  Sparry  Lime-rock  of  Eaton,  the 
Upper  Taconic  of  Emmons,  the  Quebec  and  Potsdam 
groups  of  Logan,  and  a  large  part  of  the  original  Hudson- 
River  group. 

§  140.  That  the  Levis  limestones  and  Phyllograptus 
shales,  found  at  the  summit  of  this  series,  mark  the  begin- 
nings of  the  second  fauna  has  already  been  noticed,  as 
well  as  the  fact  that  still  higher  strata,  of  Ordovician  and 
Silurian  ages,  are  found  over  portions  of  this  Appalachian 
Cambrian  series,  among  the  strata  of  which  they  have 
sometimes  been  involved  by  subsequent  movements.  It 
will  also  be  borne  in  mind :  first,  that  this  great  mass  of 


:  w  '4 


3Y. 


IXI. 


XI.] 


THE  TACONIC   HISTORY   REVIEWED. 


G27 


praent  of  the 
ewfoundland, 
irondack  and 
iiderstand  the 
3  Appalachian 
can  paleozoic 
astward  to  the 
along  the  west-  . 

;.    These  Cam- 
(ver  preserved, 
\    considerable 
3cumulation   of 
.utegratiou  and 
tan  rocks  which 
this,  and  to  re- 
[  i,i'ter  theCam- 
nstitution,  their 
i  condition,  and 
racters  serve  to 
tal  and  compara- 
limestones,  their 
Lcr  of  the   gveat 
,Iississippi  areas, 
thousand  feet  in 
a,  constitutes  the 
,ck  of  Eaton,  the 
|ec   and   Potsdam 
original  Hudson- 
id  Phyllograptus 
mark  the  begin- 
been   noticed,  as 


)f  Ordovician 


and 


this  Appalachian 
which  they  have 
it  movements.     It 
this  great  mass  of 


10,000  feet  or  more  of  diversified  and  folded  Cambrian 
strata  is  exchanged  in  the  Adirondack  and  Mississippi 
areas  for  a  far  more  simple  type  of  horizontal  strata,  but 
a  few  hundred  feet  in  thickness;  and,  secondly,  that  ero- 
sion has  removed  this  great  series  wholly  or  in  part  from 
over  large  portions  of  its  original  area. 

§  141.  With  these  explanations  before  us,  we  are  now 
prepared  to  consider  the  relations  of  the  Cambrian  and 
Ordovician  series,  in  their  two  unlike  types  of  the  Appa- 
lachian and  Adirondack  areas,  to  the  Lower  Taconic 
limestones.  It  has  already  been  shown  that  Emmons,  in 
1842,  in  his  final  report  on  the  geology  of  the  Northern 
district  of  New  York,  defined,  with  the  present  names, 
the  lower  subdivisions  of  the  New  York  paleozoic  system, 
from  the  Potsdam  to  the  Oneida  sandstone,  both  inclusive, 
to  which  he  gave  the  collective  appellation  of  the  Cham- 
plain  division. 

[He  at  the  same  time  proposed  for  the  Primitive 
Quartz-rock,  the  Primitive  Lime-rock,  and  the  Tran- 
sition Argillite  of  Eaton,  together  with  the  First  or 
Transition  Gray wacke  —  called  by  Emmons  the  Taconic 
slates  —  and  the  Sparry  Lime-rock  of  Eaton,  the  general 
name  of  the  Taconic  system.  The  Taconic  slates  were 
then  described  by  him  as  a  great  mass  of  argillites  with 
interbedded  limestones  and  coarse  sandstones,  limited  on 
the  east,  in  his  original  section,  by  the  Sparry  Lime-rock 
at  the  base  of  the  Taconic  hills,  and  on  the  west  by  "  the 
Loraine  or  Hudson-River  shales,"  bv  which  the  Taconic 
slates  were  declared  to  be  undoubtedly  overlapped,  al- 
though the  line  of  junction  on  the  west  was  said  to  be  ob- 
scure. This  intermediate  mass,  whose  limits  were  thus 
clearly  defined  to  the  west  of  the  Taconic  hills  in  1842, 
was  farther  said  in  1846  to  have  an  immense  thickness, 
and,  in  the  typical  section  in  Rensselaer  County,  a  breadth 
of  not  less  than  twenty  miles. 

[All  of  these  divisions  from  the  Primitive  Quartz-rock 
of  Eaton  to  the  Sparry  Lime-rock,  both  included,  were, 


I.  ;■     t. 


I'    ■     ;  1 


f>'  n 


'^i.. 


i!  i 


I      I. 


i,(!Mti 


i 


rb 


0J8 


THK  TACONIC  QUESTION  IN  GEOLOGY. 


vm 


by  Emmons,  in  1842,  included  in  what  he  called  the 
Taconic  system,  and  described  as  "the  rocks  lying  be- 
tween the  upper  members  of  the  Champlain  group  and  the 
Jloosic  Mountain."  They  were  then  regarded  "  as  inferior 
to  the  Potsdam  sandstone,  or  as  having  been  deposited  at 
an  earlier  date  than  the  lowest  members  of  the  New  York 
Transition  system."  The  precise  relation  of  this  system  to 
the  Silurian  and  Cambrian  systems,  and,  indeed,  the  limits 
of  these  in  England,  were  not  at  that  date  clearly  defined, 
but  Emmons  then  supposed  that  the  Taconic  rocks  in  part 
might  "be  equivalent  to  the  Lower  Cambrian  of  Sedg- 
wick,"—  "the  upper  portion  being  the  lower  part  of 
the  Silurian  system,"*  to  which  the  Middle  and  Upper 
Cambrian  of  Sedgwick  were  then,  on  the  authority  of 
Muxchison,  very  generally  referred.] 

§  142.  In  1843  appeared  the  final  report  by  Mather 
upon  the  geology  of  the  Southern  district  of  New  York, 
in  which  he  rejected  entirely  the  notion  of  the  Taconic 
system,  and  the  whole  teaching  of  Eaton,  asserting  that 
the  Taconic  was  nothing  more  than  a  in<';Ii'ied  funn  of 
the  Champlain  division  of  Emmons.  The  Granular 
Quartz-rock  of  the  Taconic ''c  declared  to  be  Potsdam; 
the  Granular  L^ne-rock,  xiie  (  ilciferous  Sand-rock  with 
the  succeeding  Chazy  ami  Ti_  ..ton  limestones;  while  the 
overlying  strata,  including  the  Taconic  slates  or  First 
Graywacke,  were  the  Utica  and  Loraine  shales.  A  simi- 
lar suggestion  had  been  put  forth  by  Messrs.  H.  D.  and 
W.  B.  Rogers,  in  1841,  for  the  like  rocks  in  New  Jersey  and 
Pennsylvania,  and  was  cited  by  Mather  in  support  of  his 
view.  When,  later,  in  1858,  H.  D.  Rogers  publislied  his 
final  report  on  the  geology  of  Pennsylvania,  the  Lower 
Taconic  rocks  of  Massachusetts  had  been  by  Emmons 
traced  south  westward  through  Pennsylvania,  in  the  great 
Appalachian  valley,  and  the  adjacent  and  subordinate 
Lancaster    valley.      These    rocks,    under  the   names   of 

*  Eraiu'^ns,  Geology  of  the  Northern  District  of  New  Yorlc,  1842,  pp. 
1-iO,  144,  163. 


XL] 


lY. 


[XI. 


THE  TACONIC   HISTORY  REVIEWED. 


629 


e   called  the 
ks  lying  be- 
yroup  and  the 
d  "  as  inferior 
a  deposited  at 
the  New  York 
this  system  to 
Loed,  the  limits 
ilearly  defined, 
Lc  rocks  in  part 
brian  of  Sedg- 
lower   part   of 
.die  and  Uppe^' 
.16  authority  of 

port  by  Mather 
t  of  New  York, 
of  the  Taconic 
1,  asserting  that 
o-Jl'-led  form  of 
The    Graiiular 
to  be  Potsdam; 
Sand-rock  with 
[tones;  while  the 
slates   or  First 
shales.      A  simi- 
^essrs.  H.  D.  ana 
n  New  Jersey  and 
in  support  of  his 
ers  published  lus 
vania,  the  Lower 
,een  by  Emmons 
ania,  in  the  great 
and  subordinate 
[er  the   names   of 
If  New  York,  1842,  pp. 


Primal,  Auroral,  and  Matinal,  were  now  described  by 
H.  D.  Rogers  as  local  modifications  of  the  Champlain  series, 
—  the  great  Auroral  limestone  being  assumed  to  be  the 
representative  of  the  Calciferous,  the  Chazy,  and  the  so- 
called  Birdseye  and  Black-River  subdivisions,  while  the 
Matinul  slates  were  supposed  to  represent  the  upper  part  of 
the  Trenton,  with  the  Utica  and  the  Loraine  shales.  For 
many  details  with  regard  to  the  facts  noticed  in  this  para- 
graph, and  for  other  points  in  the  Taconic  history,  the 
reader  is  referred  to  the  author's  volume  on  "Azoic 
Rocks."     8ee  also  ante,  pp.  533-535. 

§  143.  Coupled  with  this  , . ow  of  Mather  was  that  of  a 
progressive  alteration  of  these  uncrystalline  rocks  of  the 
Champlain  division,  supposed  to  be  traced  through  the 
Taconic  strata  into  the  crystalline  schists  of  western  New 
England,  designated  by  Mather  as  Metamorphic  rocks; 
between  which  and  the  Taconic,  it  was  said  by  him,  "no 
well  marked  line  of  distinction  can  be  drawn,  as  they 
blend  into  each  other  by  insensible  shades  of  difference." 
He  was  at  length  led  to  extend  this  same  hypothesis  to 
the  more  massive  gneisses  and  crystalline  limestones  of 
southern  New  York,  and  to  conclude  that  these  also  were, 
wholly  or  in  great  part,  but  altered  rocks  of  the  Cham- 
plain division,  —  a  notion  which  has  lately  found  an  advo- 
cate in  Dana,  who  has  also  revived  Mather's  view  of  the 
Champlain  age  of  the  Taconic  quartz-rock  and  granular 
limestone,  as  will  be  noticed  farther  on. 

§  144.  [As  we  have  already  seen,  Eaton  had  long 
before  announced  the  existence  of  a  stratigraphic  break 
at  the  base  of  his  First  Graywacke,  —  being  the  great 
group  of  strata  called  by  Emmons  the  Taconic  slatt  in 
1842,  when  he  already  recognized  its  distinctness  iu)m 
the  underlying  portions  of  his  Taconic  system,  and  as- 
serted that  it  was  '-the  lower  part  of  the  Silurian," — that 
is  to  say,  of  the  Silurian  system  as  then  defined  by 
Murchison.  This  '-upper  portion"  of  the  Taconic  sys- 
tem, including  the  First  Graywacke  and  the  Sparry  lime- 


I        !' 


?i 


1)30 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


(XL 


stone,  Emmons  had  found  to  be  fossiliferous,  in  1844,  and 
in  1846  declared  it  to  be  the  stratigraphical  equivalent  of 
the  Calciferous  Sand-rock  of  the  Champlain  division,  of 
which  he  regarded  it  as  a  great  and  "protean  development," 
and  "ncluded  with  it  the  Red  Sand-rock  of  Vermont,  which 
he  supposed  to  represent  the  Potsdam.  It  was  not,  how- 
ever, until  1855  that  Emmons  gave  to  this  paleozic  fossili- 
ferous upper  portion  of  his  original  Taconic  system  the 
name  of  Upper  Taconic,  but  meanwhile  the  whole  of  what 
was  afterwards  called  Lower  Taconic,  —  including  the 
Primitive  Quartz-rock,  the  Primitive  Lime-rock,  and  the 
Transition  Argillite,  —  was  assigned  a  position  beneath 
the  base  of  the  New  York  system.] 

§  145.  The  above  conclusion  as  to  the  age  of  the  Red 
Sand-rock  of  Vermont  was  opposed  by  C.  B.  Adams  and 
by  W.  B.  Rogers.  The  former  maintained,  in  1846,  after 
this  announcement  by  Emmons,  the  opinion  that  this 
saiid-rpck  was  newer  than  the  Champlain  division,  and 
refcred  it  to  "the  period  Oj.  the  Medina  sandstone  and 
tlio  Clintcn  group,"  while  W.  B.  Rogers,  in  1851,  discuss- 
ing the  same  subject,  conceived  that  the  reddish  limestones 
which,  near  Burlington,  Vermont,  are  associated  with  this 
sand-rock,  were  probably  "a  peculiar  development  of  the 
upper  p«jrtion  of  the  Medina  group."  As  regards  the 
relations  of  this  Red  Sand-rock  and  its  succeeding  lime- 
stone to  the  granular  quartz-rock  and  granular  lime- 
rock  of  the  Lower  Taconic,  Adams  maintained  that  "the 
Tatojuc  quartz-rock  was  probably  but  a  metamorphic 
ec<nivai3nt  of  the  Red  Sand-rock,"  and  ascribed  the 
change  to  a  supposed  "igneous  agency."  He  farther  con- 
ceived thu  the  granular  lime-rock,  "or  dlockbridge  lime- 
tstoiie  <'f  fiii  Taconic  system  is  the  equivalent  of  tlie 
calt'veius  rocks  which  overlie  the  Red  Sand-rock,  rather 
"■han  at  of  ihe  lower  limestones  of  the  Cham])lain  divis- 
ion, a  has  bjen  commonly  supposed."  Allusion  is  licie 
made  '  Adams  to  the  views  of  Mather  and  the  brothers 
Rogers,  wlio,  as  already  seen,  had  supposed  this  same 


XI.] 


THE  TACONIC   HISTORY  Ki-,VIEWED. 


6.31 


Hine.stoii3  to  be  the  equivalent  of  the  Calciferous,  Cliazy, 
and  Trenton.  T!us  oniriior.  of  Adams,  which,  in  1851, 
was,  as  we  have  shown,  supported  by  W.  B.  Rogers,  was 
again  maintained  by  the  latter  in  1860,  when,  after  the 
reading  of  an  essay  by  C.  II.  Hitchcock  before  the  Boston 
Society  of  Natural  History,  Rogers  cited  from  his  paper 
of  1851  the  conclusions  above  mentioned,  and  announced 
his  opinion  "  that  there  is  no  foundation  for  what  Mr. 
Emmons  called  his  Taconic  system  —  a  mixture  of  Silu- 
rian and  Devonian  — and  that  the  Dorset  limestone  (tlie 
Stockbridge  limestone  of  the  Lower  Taconic)  is  newer 
than  the  Lower  Silurian,  and  probably  Upper  Silurian  or 
Devonian.* 

§  146.  The  explanation  of  this  new  opinion  as  to  the 
horizon  of  the  Lower  Taconic  limestone  is  made  apparent 
by  reference  to  the  report  on  the  geology  of  Vermont, 
then  in  process  of  publication  by  the  Messrs.  Hitchcock. 
Therein  Dr.  Edward  Hitchcock  writes,  with  regar J  to  the 
limestone  in  question,  then  named  by  him  Eolian  lime- 
stone, and  said  to  be  best  displayed  in  Dorset  Mountain : 
*'  We  have  found,  mostly  in  strata  from  below  the  middle 
of  the  limestones,  fossils  which,  though  obscure  from 
metamorphism,  are  clearly  referable  to  genera  character- 
istic of  Devonian  rocks,  viz :  Euomphalus,  Stromatopora, 
Zaphrentis,  Chaetetes,  and  encrinal  stems."  "Nor  is  it  at 
all  improbable,  as  we  shall  shortly  show,  that  the  Eolian 
limestone  may  be  as  recent  as  the  Carboniferous  rocks."  f 
Accompanying  this  statement  is  a  notice  of  these  organic 
forms  as  determined  by  Prof.  James  Hall,  wlio  declared 
them  to  be  of  Upper  Silurian  and  Devonian  types.  They 
are  compared  by  Hitchcock  to  those  found  to  the  east  of 
the  Green  Mountains,  in  the  valley  of  Lake  Memphrema- 
gog,  the  horizon  of  which  is  well  known. 

§  147.  We  have  already  noticed  the  occurrence  of  out- 
liers   of    Lower    Helderberg    limestone   on   St.    Helen's 

*  Proc.  Bost.  Soc,  Nat.  Hist.,  vii.,  238. 

t  Geology  of  Vermont,  18G1,  pp.  421,  and  418,  419. 


G32 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


txi. 


Island,  near  Montreal,  and  on  Beloeil  Mountain,  a  few 
miles  farther  east ;  in  the  first  locality  resting  unconform- 
ably  upon  Ordovician  strata,  and  in  the  second  upon  a 
mass  of  eruptive  rock  which  breaks  through  similar  strata 
(§  117).  In  this  connection  may  be  recalled  the  like 
occurrence  at  Becraft's  Mountain,  near  the  town  of 
Hudson,  on  the  east  side  of  tht  Hudson  River  long 
known,  and  lately  re-examined  by  W.  M.  Davis.  Here, 
resting  upon  shales  referred  to  the  Hudson-River  group 
and,  from  the  locality,  probably  of  Loraine  age,  there  is 
found,  in  a  small  synclinal  area,  a  mass  of  contorted 
strata,  including  150  feet  or  more  of  fossiliferous  Lower 
Helderberg  limestones  overlaid  by  as  great  a  thickness 
of  Cauda-galli  shales,  to  which  succeed  a  few  feet  of 
cherty  limestone  regarded  as  the  equivalent  of  the  Corni- 
ferous  or  Upper  Helderberg.*  In  all  of  tliese  localities, 
as  well  as  at  Rondout,  also  re-examined  by  Davis,  we  note 
the  absence,  beneath  these  Silurian  strata,  of  the  great 
mass  of  mechanical  sediments,  including  the  Oneida  and 
Medina  sandstones,  which,  farther  west,  are  so  conspicu- 
ous in  the  lower  part  of  the  Silurian  series,  and  belong  to 
the  Second  Graywacke  of  Eaton. 

[The  late  observations  of  Dwight,  Smock,  and  Darton 
(§  90  A),  showing  the  existence  of  portions  of  Silurian 
(Lower  Helderberg)  limestones,  and  even  of  Devonian 
sandstones,  in  the  Green-Pond  Mountain  area  in  New 
Jersey  and  southeastern  New  York  furnish  farther  illus- 
trations of  the  eastward  extent  of  these  higher  paleozoic 
sediments.]  • 

§  148.  As  already  mentioned  in  §  118,  Augustus  Wing 
having  detected  in  Vermont  fossiliferous  limestones  of 
Trenton  age,  the  locality  was  examined  by  Billings  In 
a  section  eastward  from  Crown  Point,  in  New  York,  the 
latter  found  what  was  described  as  tht;  Red  Sand-rock, 
with  Olenellus,  brought  up  by  a  fault  on  the  east  side  of 
the  Loraine  shales,  and  followed  eastward  by  strata  carry- 
*  Amer.  Jour.  Science,  xxvi.,  381  and  389. 


rY.  l^^- 

itain,  a  few 
f  unconforra- 
oiul  upon  a 
iimilar  strata 
led  the  like 
the    town   of 

River  long 
3avis.  Here, 
i-River  group 

age,  there  is 

of  contorted 
[ferous  Lower 
it  a  thickness 
1,  few   feet   of 

of  the  Corni- 
hese  localities, 
Davis,  we  note 
I,  of  the  great 
le  Oneida  and 
•e  so  conspicu- 

and  belong  to 

[ik,  and  Darton 
ns  of  Silurian 
of  Devonian 
area  in  New 
farther  illus- 
"■her  paleozoic 

\ngustusWing 
limestones  of 
y  Billings^  In 
New  York,  the 
Red  Sand-rock, 
,he  east  side  of 
by  strata  carry- 

38'J. 


XI.] 


THE   TACONIC    HISTORY   TvEVIEWED. 


633 


ing  the  fauna  of  the  Calciferous  Sand-rock,  succeeded  by 
some  forms  of  the  Levis,  and  then  by  the  Chazy  and 
Trenton  ;  to  the  east  of  which  another  dislocation  brings 
up  again  a  limestone  abounding  in  the  typical  fauim  of 
the  Levis  limestone.  The  close  association  of  the  latter 
witli  the  white  marbles  quarried  in  this  region,  led  Bill- 
ings to  refer  these  to  the  Levis  horizon.*  It  is  worthy  of 
notice  that  it  was  in  the  same  vicinity  which  furnished 
Billings  with  Calciferol  Levis,  Chazy,  and  Trenton 
forms,  that  the  organic  remains  had  been  found  which 
were  referred  by  Hall  to  the  Niagara  and  still  higher 
horizons,  and  had  caused  Edward  Hitchcock  and  W.  B. 
Rogers  to  conjecture  that  the  marbles  of  this  region 
juight  be  of  Devonian  age  or  younger.  So  perplexing 
were  these  facts  to  Wing,  that  we  find  him  led  to  the 
conclusion,  announced  in  a  letter  to  J.  D.  Dana  in  1875, 
and  recently  cited  with  approval  by  the  latter,!  that  "the 
Eolian  limestone  of  the  Vermont  geological  report  em- 
braced not  only  the  Trenton  and  the  Hudson-River  beds, 
hut  all  the  formations  of  the  Lower  Silurian  as  well,  and 
even  limestones  and  dolomites  of  the  Red  Sand-rock 
(Potsdam  sandstone)  series." 

§  149.  Another  h3^pothesis  touching  the  age  of  the 
Taconic  marbles  was  now  offered  to  the  perplexed  geolo- 
gist, and  this  time  by  the  geological  survey  of  Canada. 
We  have  already  shown  that,  forced  by  the  paleontological 
evidence  which  liad  previous!}^  been  lu-ged  by  Eannons, 
Logan,  in  1861,  adopted  the  views  of  the  latter  as  regards 
the  horizon  of  the  Upper  Taconic,  long  before  traced  from 
New  York  beyond  Quebec  on  the  St.  Lawrence.     This, 

*  Hunt,  On  Some  Points  in  the  Geology  of  Vermont,  1868,  Amer. 
Jour.  iScience,  xlvi.,  pp.  222,  229.  This  paper,  from  data  furnished  by 
Lilllngs,  was  written  while  the  writer  still  accepted  the  untenable  view  of 
Logan,  from  the  first  opposed  by  Billings,  which  assigned  the  Levis  or 
Spariy  limestone  to  a  position  near  the  base  of  the  Cambrian  series,  in- 
stead of  its  summit. 

t  Dana,  The  Age  of  the  Taconic  System,  Quar.  Geological  Journal, 
xxxviii.,  402. 


'i 


r 

il 

^1 

/  : 
'  ,1 

I 

G34 


THE  TACONIC   QUESTION   IN   GEOLOGV. 


[XT. 


iij  acctii'diince  with  the  conclusions  of  Mather,  and  the 
earlier  published  view  of  Emmons,  had  been  described  by 
Logan  as  consisting  of  the  Hudson-River  group  with  the 
addition  of  the  Oneida  sandstone.  The  study  of  its  fossils 
by  Billings  now  led  Logan  to  see  that  its  position  was 
really  below  and  not  above  the  Trenton  limestone ;  but 
instead  of  adopting  Emmons'  later  name  of  Upper 
Taconic,  he  gave  to  the  series,  as  seen  near  Quebec,  the 
name  of  the  Quebec  group,  then  described  by  Logan  as  a 
stratigraphical  equivalent  of  the  Calciferous  Sand-rock. 
Taking  as  a  type  the  well  known  section  there  displayed 
upon  the  St.  Lawrence,  he  called  the  ap})arently  super- 
posed sandstone  the  Sillery,  and  the  underlying  fossil- 
iferous  limestones  and  shales  (the  Sparry  Lime-rock  of 
Eaton)  the  Levis  division.  This  was  a  reversal  of  the 
order  described  by  former  observers,  and  there  can  be  no 
doubt  that  the  section  at  Quebec  is  really  an  inverted 
one,  the  Sillery  sandstone  being  the  oldest  and  not  the 
youngest  member  of  the  series  as  there  displayed.  This 
history  has  already  been  given  at  length,  in  chapter  vi. 
of  this  essay. 

§  150.  We  have  there  also  explained  how  Logan's  view 
of  the  position  of  the  Sillery  sandstone  was  made  to 
support  the  notion  that  the  crystalline  schists  which  iuive 
been  found  to  underlie  it  were  the  altered  representatives 
of  the  sedimentary  strata  found  between  the  Sillery  uad 
the  Levis,  which  he  had  called  the  Luuzon  division. 
Following  the  r  jcks  of  his  Quebec  group  southward  into 
Vermont  until  he  met  the  granular  marbles  of  the  Lower 
Taconic,  Logan  was  led  to  include  these  also  in  the 
Quebec  group,  and  to  regard  them  as  the  Levis  limestone 
in  an  altered  condition.  This,  as  already  set  forth  in 
§§  115-116,  is  seen  in  his  large  geological  map  of 
Canada  and  the  Northern  States,  published  in  186G,  after 
he  had  spent  some  time  in  tracing  these  rocks  through 
western  Vermont  and  Massachusetts  into  eastern  New 
York.     Therein  the  Lower  Taconic  limestone  in  Massa- 


JGY.  ^•^'■ 

ither,  and  tlio 
1  described  by 
rroup  with  the 
Idy  of  its  fossils 
,s  position  wiis 
limestone;  but 
ame    of   Upper 
>ar  Quebec,  the 

by  Logan  as  a 
lous  Sand-rock. 

there  disphiyed 
pparently  super- 
mderlying  fossil- 
ry  Lime-rock  of 

reversal  of  the 

there  can  be  no 
.ally  an  inverted 
dest  and  not  the 
.displayed.  This 
th,  in  chapter  \i. 

how  Logan's  view 
ue   was   made    to 
chists  which  have 
ad  representatives 
u  the  Sillery  and 
Luuzon  division. 
^,  soutliward  into 
bles  of  the  Lower 
these   also   in  the 
le  Levis  limestone 
veady  set  forth  in 
eologioal    map    ot 
,hed  in  186G,  after 
,ese  rocks  through 
into  eas^^rn   New 
imestoue  in  Massa- 


XI.] 


THE  TACONIC   IIISTOUY   liEVIliWED. 


Olio 


chusetts  is  represented  as  an  uninterrupted  continuation 
of  tlie  Levis  limestone  from  the  province  of  Quebec, 
brought  up  along  an  anticlinal,  and  having  on  both  sides 
overlying  it,  successively,  ti>»-  Lauzon  and  Sillery  divis- 
ions,— these,  on  the  west  side  of  the  anticlinal,  having  the 
ordinary  type  of  the  uncrystalline  First  Grayvvacke  or 
Upper  Taconic,  but  being  represented  on  the  east  side  by 
the  crystalline  schists  of  the  Green  Mountain  range,  their 
supposed  e(iuivalents.  Few  will  now  question  that  Logan 
was  wrong  in  this  latter  point,  or  will  doubt  the  greater 
anti(iuity  of  these  crystalline  rocks.  On  the  other  hand,  it 
is  to  be  noted  that,  in  thus  asserting  the  infraposition  of 
the  Lov/er  Taconic  marbles  to  tiie  First  Graywacke  or 
Upper  Taconic  series,  Logan  but  confirmed  the  older 
ob  irvations  of  Eaton  and  Ennnons,  and  only  erred  in 
having,  by  a  false  interpretation  of  the  succession  of  the 
latter  series  near  Quebec,  assigned  the  Levis  limestone  to 
its  base,  by  which  he  was  led  to  confound  ii  vyith  the 
Lower  Taconic  limestone.  In  either  view,  he  placed  the 
latter  below  the  series  of  several  thousand  feet  of  sand- 
stones, conglomerates,  and  shales,  which  constitute  the 
First  Graywacke  of  Eaton  and  the  Upper  Taconic  of 
Emmons. 

§  151.  We  have  already  seen  that  Emmons,  as  early  as 
1846,  had  recognized  the  fossiliferous  character  of  the 
First  Graywacke,  which  he  afterwards  called  Upper 
Taconic ;  that  he  described  and  figured,  in  184G,  trilobitic 
forms  found  therein,  and  did  not  hesitate,  in  1860,  to 
declare  that  it  corresponded  with  the  Primordial  zone  of 
Barrande.*  Thus  it  happened  that  Barrande,  Marcou, 
and  after  him  Perry,  assumed  the  Taconic  system  to  be 
the  equivalent  of  the  Primordial  zone  or  Cambrian  of 
Great  Britain,  Bohemia,  and  Spain,  —  they  having  failed 
to  recognize  the   distinction   which  Emmons  had  made, 

*  See,  In  this  connection,  Barrande  and  Marcou  on  the  Primordial 
Fauna  and  the  Taconic  System ;  Froc.  Boston  Soc.  Nat.  Hist.,  Dec, 
1860,  vol.  vii.,  pp.  369-382. 


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636 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


tXI. 


as  early  as  1842,  between  the  lower  and  upper  divisions 
of  his  original  Taconic,  when  he  referred  the  upper  por- 
tion to  wliat  he  then  called  the  Silurian  system.  In  1867, 
J.  B.  Perry  described  the  Taconic  system  of  Vermont  as 
composed  of  three  parts :  1.  Lower,  consisting  of  quartz- 
ites,  marbles,  and  talcoid  schists,  the  Lower  Taconic  of 
Emmons;  2  and  3.  Middle  and  Upper,  including  the  un- 
crystalline  fossiliferous  Scranton  and  Georgia  slates,  and 
the  overlying  Red  Sand-rock,  which  he  regarded  as  the 
equivalent  of  Potsdam.  The  succeeding  graywacke,  con- 
stituting a  great  part  of  the  Upper  Taconic  of  Emmons, 
was  by  Perry  supposed  to  be  separated  by  an  unconformity 
from  the  Red  Sand-rock,  and  he  was  disposed  to  divide 
it  from  the  Taconic  and  connect  it  with  the  Champlain 
division.* 

§  152.  Still  more  recently  Marcou  has  given  us  his 
own  later  views  of  these  rocks  in  Vermont.  The  true  or 
typical  Taconic  is,  according  to  him,  the  Upper  Taconic 
of  Emmons,  and  rests  unconformably  upon  the  Lower 
Taconic.  This  upper  series  he  divides  into  four  parts, 
in  ascending  order,  designated  the  St.  Albans,  Georgia, 
Phillipsburg,  and  Swanton  groups.  In  these  are  found, 
besides  the  Primordial  fauna,  fossils  of  i'le  second  fauna 
in  included  limestones,  a  fact  which  he  explains  as  indi- 
cating centres  of  creation  in  which  the  forms  of  the  second 
fauna  first  made  their  appearance ;  the  whole  of  these 
being,  according  to  him,  below  the  horizon  of  the  Red 
Sand-rock,  which  he  supposes  to  overlie  unconformably 
the  Upper  Taconic.f  That  the  forms  of  the  second  fauna 
found  in  portions  of  this  region  belong  to  a  lower  hori- 
zon than  the  Potsdam,  is  in  discordance  alike  with  the 
facts  of  paleontology  and  of  stratigraphy,  and  is  opposed 
to  the  conclusions  of  all  other  observers  in  that  region, 
including  alike  Emmons,  Logan,  and  Perry.     Marcou's 

*  The  Red  Sand-rock  of  Vermont,  etc.,  J.  B.  Perry  ;  Proc.  Bost.  See. 
Nat.  Hist.,  1867,  vol.  xi. 

t  Marcou,  Bull.  Soc.  G^ol.  de  France  1880  (3),  Ix.,  pp.  lcS-46. 


LOGY. 


[XI. 


vXL] 


THE  TACONIC   HISTORY   KEVIEW3D. 


63T 


upper  divisions 
the  upper  por- 
stem.    In  1867, 
1  of  Vermont  as 
isting  of  quartz- 
ovver  Taconic  of 
icluding  the  un- 
;orgia  slates,  and 
regarded  as  the 
y  graywacke,  con- 
mic  of  Emmons, 
r  an  unconformity 
Lisposed  to  divide 
h  the  Champlain 

has  given  us  his 
out.     The  true  or 
le  Upper  Taconic 
upon  the  Lower 
8  into  four  parts, 
Albans,  Georgia, 
these  are  foiuid, 
ciie  second  fauna 
3  explains  as  indi- 
'orms  of  the  second 
he  whole  of  these 
orizon  of  the  Red 
•lie  un conformably 
f  the  second  fauna 
g  to  a  lower  hori- 
ice  alike  with  the 
hy,  and  is  opposed 
ers  in  that  region, 
Perry.     Marcou's 

Iperry  ;  Proc.  Boat.  Soc. 
,  ix.,  pp.  18-46. 


conclusions  would  seem  to  be  based  on  some  of  the  fre- 
quent cases  of  inversion  of  strata,  or  of  dislocation  and 
upthrow,  to  wbich  we  have  elsewhere  alluded,  and  which 
led  Logan  to  place  the  Levis  limestone  near  Quebec 
at  the  base  of  his  Quebec  group,  and  to  represent  the 
Taconic  marbles  of  southern  Vermont  as  passing  below 
the  crystalline  schists  of  the  Green  Mountain  range. 

It  should,  however,  here  be  said,  at  the  same  time,  that 
in  a  disturbed  region  like  eastern  Vermont,  where  areas 
of  the  higher  rocks  of  the  second  fauna  exist,  and  have 
probably  at  one  time  been  more  widely  spread  than  now, 
it  is  not  impossible  that  there  may  be  outliers  of  a  sand- 
stone of  Oneida  or  Medina  age,  such  as  in  Pennsylvania 
we  have  described  as  overlying  unconformably  Lower 
Taconic  rocks,  and  also  that  such  higher  sandstones 
may  have  been  confounded  with  the  older  Cambrian  or 
Potsdam  sandstone,  and  thus  afford  a  seeming  justifica- 
tion for  the  strange  hypothesis  advanced  by  Marcou,  that 
the  whole  of  the  Appalachian  Cambrian  in  Vermont  is 
older  than  the  Lower  Potsdam.  [The  late  discovery 
in  the  Green-Pond  Mountain  range,  in  New  Jer.sey,  in 
close  association  with  older  sediments,  of  •Silurian  lime- 
stones and  Devonian  sandstones,  as  mentioned  in  §  148, 
is  significant  in  this  connection.] 

§  153.  The  studies  of  the  last  few  years  have  thrown 
much  light  on  the  character  of  the  lower  portions  of  the 
Cambrian  in  its  development  to  the  east  and  southeast  of 
the  Adirondack  area.  It  has  been  noticed  tliat  the  Red 
Sand-rock  and  its  accompanying  slates  and  limestones 
near  Burlington,  Vermont,  referred  by  Emmons  to  the 
Potsdam,  but  by  Adams  and  W.  B.  Rogers  to  the  Medina, 
and  by  Logan  to  the  summit  of  the  Hudson-River  groUp, 
were  subsequently  by  Billings  called  Lower  Potsdam,  to 
indicate  that  the  fauna  of  these  rocks  belongs  to  a  some- 
what lower  horizon  than  the  typical  Potsdam  of  tlie  New 
York  system.  The  later  studies  of  Logan  in  western 
Vermont,  as  given  by  him  in  1863,  showed  that  these 


:!:>sr' 


i:l:^'iil 


fl-'i   n 


638 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


tXI. 


ancient  rocks  are  brought  up  by  a  north  and  south  dislo- 
cation, with  an  upthrow  on  the  east,  from  beneath  rocks 
of  Trenton,  of  Chazy,  or  of  Levis  age,  which  latter  here 
occupy  their  natural  position  at  the  summit  of  the  Upper 
Taconic  or  First  Graywacke  group.*  Billings,  also,  in 
1868,  as  already  pointed  out,  had  shown  that  farther 
southward  in  Vermont  the  Red  Sand-rock,  or  Lower 
Potsdam,  is  in  like  manner  brought  up  by  a  dislocation, 
80  as  to  overlie  on  the  east  the  Loraine  shales. 

§  154.  It  was  now  clear  to  all,  that  much  of  what  had 
been  called  Hudson-River  group  to  the  east  of  the  Hud- 
son valley  and  of  Lake  Champlain,  consisted,  not,  as 
taught  by  Mather  and  his  followers,  of  disturbed  and 
altered  strata  newer  than  the  Trenton  limestone,  and  of 
the  age  of  the  Loraine  shales,  but  of  older  rocks,  carrying, 
in  part,  at  least,  the  forms  of  the  first  fauna.  We  have 
already  seen  (§  112)  how,  in  view  of  these  facts.  Hall 
expressed  his  opinion,  in  1862,  as  to  the  relations  of  these 
newer  strata  to  the  older  ones.  In  1877,  he  returned  to 
the  subject,  and,  after  retracing  the  history  of  investiga- 
tion, concluded  that  "we  now  know  approximately  the 
limits  between  the  newer  and  the  older  formations,  and 
there  is  now  no  longer  any  question  that  the  newer  series, 
or  the  rocks  above  the  Trenton  limestone,  do  occupy  both 
sides  of  the  Hudson  River  for  nearly  one  hundred  miles, 
and  continue  along  the  valley  for  many  miles  farther 
towards  Lake  Champlain.  The  term  Hudson-River 
group  has,  therefore,  a  definite  signification,  from  abso- 
lute knowledge  of  superposition  and  fossil  remains.  The 
error  lay  in  extending  the  term  to  rocks  on  the  eastward, 
at  a  time  when  their  fossil  contents  had  not  been  studied, 
and  were,  in  fact,  unknown,  and  their  geological  position 
had  not  been  determined  by  critical  examination."  f  The 
distinction  between  the  two  had  however  been  clearly 
pointed  out  by  Emmons  as  early  as  1842  (awfe,  p.  586.)  We 

*  Geology  of  Canada,  cliap.  xxii.,  pp.  844-800.  , 

t  Hall,  Proc.  Amer.  Assoc.  Adv.  Science,  1877,  p.  263. 


XL] 


THE  TACONIC   HISTORY   REVIEWED. 


639 


have  already  shown  in  §§  13-14  how  Vanuxem  had  de- 
vised this  term  to  include,  besides  the  true  Loraine  shales, 
other  disturbed  and  apparently  non-fossiliferous  rocks  of 
controverted  age,  which  he  supposed  might  be  included 
with  the  former,  and  thus  introduced  much  of  that  con- 
fusion which  has  prevailed  in  the  use  of  the  name  of 
Hudson-River  group  as  the  equivalent  to  Loraine  shales. 

§  155.  The  eastern  limit  of  the  rocks  of  the  second 
fauna,  along  the  Hudson  valley,  being  defined  as  stated 
by  Hall,  and  as  already  shown  by  him  for  that  region  on 
Logan's  geological  map  previously  published,  it  was  im- 
portant to  determine  the  age  of  the  uncrystalline  rocks 
along  their  eastern  border,  and  to  decide  whether  these 
were  (as  mapped  by  Logan)  portions  of  the  so-called 
Quebec  group,  or  of  the  still  older  Potsdam  which  had 
been  found  in  this  position  at  several  points  in  Vermont. 
Nothing  has  contributed  more  to  the  solution  of  this 
problem  than  the  careful  studies  of  Mr.  S.  W.  Ford,  who, 
in  1871,  discovered  the  existence  of  fossiliferous  rocks  of 
this  lower  horizon  at  Troy,  New  York,  and,  following  up 
his  investigations,  showed  that  these  strata,  containing  an 
abundant  fauna  of  Lower  Potsdam  age  (corresponding  to 
the  Olenellus  slates  of  Georgia,  Vermont,  and  to  the  beds 
at  Bic,  Quebec,  and  at  the  Strait  of  Bellisle,  in  Labrador), 
are  at  Troy  broug]it  up  on  the  eastern  side  of  a  fault, 
against  the  Loraine  shales.*  Continuing  his  studies.  Ford 
has  recently  traced  these  Lower  Potsdam  rocks,  under 
similar  conditions,  through  various  parts  of  Columbia  and 
Dutchess  Counties,  the  stratigraphical  break  and  the  up- 
throv  of  the  Cambrian  strata  on  its  eastern  side  being 
well  defined.  He  does  not  attempt  to  estimate  the  thick- 
ness of  this  series  of  Cambrian  sandstones,  shales,  con- 
glomerates, and  limestones,  but  says  that  it  "  is  manifestly 
very  great  in  eastern  New  York,"t  Emmons  having 
already  in  1846  declared  its  volume  to  be  probably  equal 

*  Amer.  Jour.  Science,  1873,  vl.,  p.  135. 

t  Amer.  Jour  Science,  1884,  xxviii.,  pp.  35  and  206. 


>M  :':■: 


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640 


THE  TACONIC   QUESTION  IN   GEOLOGY. 


[XI. 


to  thai  of  all  the  members  of  the  New  York  system  in 
their  ordinary  development  (ante,  p.  586). 

§  156.  It  is  hardly  necessary  to  mention  that  this 
series  of  Cambrian  fossiliferous  rocks,  traced  by  Ford 
through  Rensselaer,  Columbia,  and  part  of  Dutchess  Coun-. 
ties,  along  the  eastern  side  of  a  belt  of  Loraine  shales, 
is  a  part  of  the  First  Graywacke  belt  of  Eaton,  tlie 
Upper  Taconic  of  Emmons,  which  Logan,  after  his  ex- 
amination of  the  region  with  Hall,  in  1863,  described 
and  subsequently  mapped  as  Quebec  group.  These  ob- 
servers, as  has  been  already  stated  (§  115),  and  as  may 
be  seen  on  Logan's  map  of  1866,  then  traced  a  narrow  buL 
persistent  belt  of  Loraine  shales  along  the  eastern  side  of 
the  Hudson,  from  Washington  County  southward  to  a 
point  a  little  above  Hyde  Park,  where  they  found  the 
boundary  between  these  shales  and  the  older  group  to 
cross  to  the  west  side  of  the  Hudson.  The  accuracy  of 
this  delineation  is  confirmed  by  Ford,  who,  while  remark- 
ing that  the  distribution  of  the  upper  rocks  might  entitle 
them  to  be  called  the  Hudson-River  group,  suggests,  in 
view  of  the  perplexities  which  have  attended  its  use,  that 
it  would  be  better  "  to  discard  altogether  the  designation, 
and  go  back  to  the  old  term,  Loraine  shales."  Ford 
farther  speaks  of  the  "great  dislocation,"  which,  at  so 
many  points  from  western  Vermont  to  the  Hudson  in 
Dutchess  County,  brings  up  the  Cambrian  rocks  against 
newer  strata  of  Ordovician  age.  A  reference  to  the  sec- 
tions of  Logan  and  Billings,  already  cited,  will,  however, 
show  the  existence,  not  of  a  single  dislocation,  but  of 
parallel  dislocations,  with  upthrows  on  the  east  side, 
towards  the  barrier  of  older  rocks.  Of  such  parallel 
faults  we  find,  in  fact,  repeated  examples,  not  only  east  of 
the  Hudson,  but  farther  southward  in  many  places,  along 
the  eastern  border  of  the  Appalachian  valley,  as  already 
pointed  out,  in  §  101. 

§  157.  The  one  continuous  break,  with  an  upthrow,  on 
the  south  and  east,  of  7000  feet,  extending  from  Gasp^  to 


lY. 


IXI. 


XI.] 


THE  TACONIC   HISTORY   REVIEWED. 


641 


)rk  system  in 

ion  that    this 
iced  by  Ford 
)utchess  Coun-, 
Loraine  shales, 
of    Eaton,   the 
n,  after  his  ex- 
1863,  described 
Lip.      These  ob- 
5),  and  as  may 
ed  a  narrow  but 
J  eascern  side  of 
southward  to  a 
they  found  the 
older  group  to 
The  accuracy  of 
10,  while  remark- 
pks  might  entitle 
roup,  suggests,  in 
[nded  its  use,  that 
the  designation, 
,  shales."      Ford 
,n,"  which,  at  so 
b  the  Hudson  in 
[ian  rocks  against 
grence  to  the  sec- 
;ed,  will,  however, 
islocation,  but  of 
fn  the   east    side, 
,0f    such  parallel 
s,  not  only  east  of 
tany  places,  along 
valley,  as  already 

Ith  an  upthrow,  on 
ling  from  Gasp6  to 


Alabama,  imagined  by  Logan,  was  required  in  his  struc- 
tural scheme,  because  he  had  assumed  the  Levis  limestone, 
(which  near  Quebeo  is  brought  to  adjoin  the   Loraine 
shales),  to  occupy  a  position  at  the  base  of  his  Quebec 
group,   and  to  have   been   originally  buried    7000    feet 
beneath  the  Loraine  shales,  in  a  great  conformable  series. 
The  strata  along  the  west  side  of  these  dislocations  in 
Canada  and  in  Vermont  are,  according  to  Logan,  either 
Levis,  Chazy,  Trenton,  or  Loraine,  the  Lower  Potsdam 
being  on  the  east  side.      In  a  section  described  by  Bill- 
ings, and  already  noticed  (§  148),  where  the  first  disloca- 
tion brings  up  the  Lower  Potsdam  —  which  is  successively 
overlaid  by  Calciferous,  Levis,  Chazy,  and   Trenton  — 
against  the  Loraine,  a  second  parallel  fault,  a  little  farther 
to  the  east,  brings  up  the  Levis  against  the  Trenton.    We 
see,  from  the  late  studies  of  Ford,  that  the  great  belt 
along  the  eastern  border  of  the  Loraine  shales,  which 
Logan  described  and  mapped  as  Quebec  group,  is  iu  large 
part  Lower  Potsdam.     The  whole  series  must  now  be 
farther  studied  in  the  present  light :    we  must  know  the 
real  thickness  of  the  Cambrian  in  the  region  in  question  ; 
the  interval  therein  which  separates  the  Lower  Potsdam 
from  the  Levis  fauna;    and  how  much  of  the  Quebec 
group  of  Logan  is  to  be  included  in  the  Potsdam. 

§  158.  As  regards  the  relations  of  the  Cambrian  and 
Ordovician  rocks  over  this  area,  we  have  already  shown 
that  there  is  every  reason  to  believe  that  there  exists  a 
stratigraphical  break  between  them  (as  is  alsb  the  case 
between  the  Lower  Taconic  and  Cambrian)  and  farther, 
that  the  lower  members  of  the  Ordovician  series  (tlie 
limestones  of  the  Trenton  group)  thin  out  and  present, 
irregularities  to  the  south  and  east.  Although  to  Hall 
and  Logan  it  appeared  that  the  line  between  the  Loraine 
shales  and  the  inferior  series  passed  from  the  east  to  the 
west  bank  of  the  Hudson  near  Hyde  Park  in  Dutchess 
County,  subsequent  studies  *  have  shown  the  existence  of 
*  Amer.  Jour.  Science,  xvii.,  57. 


U 


'f:       ■■! 


it 


mm 


642 


THE  TACONIO  QUESTION  IN  GEOLOGY. 


[XI. 


the  higher  strata  farther  southward,  on  the  east  bank. 
Dale,  in  1877,  found  fossils  of  the  Loraine  period  in  shales 
at  Poughkeepsie,  and  Dwight  soon  after  detected  abun- 
dant forms  of  Trenton  age  in  the  limestone  of  the  Wap- 
pinger  valley,  a  little  farther  south,  as  well  {is  at  Newburg 
on  the  west  bank  of  the  Hudson.  These  discoveries  were 
soon  followed  by  that  of  a  remarkable  fauna  of  Calcifer- 
ous  age  in  other  limestones  in  the  Wappinger  valley,  thus 
showing  the  presence  here,  as  in  Vermont,  to  the  east  of 
the  outcrop  of  the  Cambrian,  of  strata  carrying  the  fossils 
of  the  Calciferous,  the  Trenton,  and  the  Loraine  subdi- 
visions. These  observations  by  Dwight  were  made  in 
1877-1880,*  and  joined  to  those  of  Dale,  and  those  of 
Ford,  show  the  existence,  in  what  has  there  been  called 
both  Hudson-River  group  and  Quebec  group,  of  fossil- 
iferous  strata  ranging  from  the  Lower  Potsdam  to  the 
Loraine,  both  inclusive, —  a  result  identical  to  that  already 
arrived  at  in  Canada  for  the  area  which  had  been  succes- 
sively mapped  as  Hudson-Rivrr  group  and  Quebec  group. 

§  159.  Having  thus  recalled  the  latest  results  of 
paleontological  research  among  the  so-called  Upper 
Taconic,  and  shown  the  association  of  areas  of  Ordovi- 
cian  rocks  with  the  predominant  Cambrian,  we  may  pro- 
ceed to  notice  the  views  of  Prof.  J.  D.  Dana  on  the 
Taconic  question.  He,  in  1872  and  1873,  published  an 
extended  series  of  papers  on  the  rocks  of  the  Taconic 
range,  as  seen  in  Berkshire  County,  Massachusetts,  and 
reasoning  from  the  organic  forms  found  in  association 
with  similar  limestones  in  Vermont,  reached  the  conclu- 
sion that  the  Stockbridge  limestone  "  is  mainly  Trenton," 
the  overlying  schists  being  of  the  Hudson-River  group.f 
This  latter  statement,  supported  by  a  stratigraphical  argu- 
ment, may  be  found  in  his  paper  on  The  Geological  Age 
of  the  Taconic  System. 

§  160.    [In  the  paper  just  named   (communicated  to 

*  Amer.  Jour.  Science,  xvii.,  389;  xix.,  50;  xxi.,  78;  and  xxvii.,  249. 
t  Ibid.,  vL,  274. 


OGY. 

the  east  bank, 
period  in  shales 
detected  abun- 
le  of  the  Wap- 
L  as  at  Newburg 
discoveries  were 
iina  of  Calcifer- 
nger  valley,  thus 
t,  to  the  east  of 
.rrying  the  fossils 
e  Loraine  subdi- 
ht  were  made  in 
ale,  and  those  of 
there  been  called 
3  group,  of  fossil- 
,r  Potsdam  to  the 
[cal  to  that  already 
1  had  been  succes- 
land  Quebec  group, 
latest    results    ot 
so-called    Upper 
,f  areas  of  Ordovi- 
brian,  we  may  pvo- 
D.  Dana  on  the 
x873,  published  an 
sks  of  the  Tacomc 
Massachusetts,  and 
und  in  association 
reached  the  conclu- 
is  mainly  Trenton, 
ddson-River  group-t 
stratigraphical  argu- 

The  Geological  Age 

(communicated  to 
^.,18;  andxxvll.,249. 


XI.] 


THE  TACONIO  HISTORY  REVIEWED. 


643 


the  Geological  Society  of  London  in  1882),*  Dana  pro- 
poses to  limit  the  question  to  the  Taconic  hills,  and  the 
area  originally  described  by  Emmons.  He  claims  that 
the  "  true  original  Taconic  schists "  are  those  of  the  Ta- 
conic range,  extending  north  and  south  along  the  boundary 
between  Massachusetts  and  New  York,  including  the 
counties  of  Rensselaer  and  Columbia  in  the  latter  State, 
to  which  he  adds  Dutchess  County  on  the  south.  In  the 
centre  of  the  range  are,  according  to  him,  these  "Taconic 
schists,"  having  on  the  east  the  Stockbridge  limestone 
(the  latter  being  three  times  repeated,  with  intervening 
Granular  Quartz-rock  and  the  Magnesian  slates  of  Em- 
mons), and  on  the  west  the  Sparry  limestone  or  Sparry 
Lime-rock  of  Eaton,  all  the  strata  having  a  general  eastern 
dip.  Dana  declares  that  these  three  rocks  —  by  which  he 
means  the  Stockbridge  limestone,  the  Magnesian  slate, 
and  the  Sparry  Lime-rock,  neglecting  the  Granular 
Quartz-rock  —  "are  all  that  need  be  considered,"  and  that 
the  only  question  is  whether  these  limestones  are  the 
same  rock,  repeated,  with  alterations  in  character,  to  the 
eastward,  or  whether  the  Sparry  Lime-rock,  which  seems 
to  dip  beneath  all  the  others,  is  a  newer  rock  or  an  older 
rock  than  they.  Emmons,  in  1842,  was  perplexed  by  the 
continuous  eastern  dip  of  the  strata  across  a  great  breadth 
of  country,  and  expressed  doubts  on  this  point,  which  he 
was,  however,  enabled  to  solve  before  1846,  and  to  assure 
himself  that  the  position  of  the  Sparry  limestone  was 
younger  than  the  Stockbridge  limestone,  or  the  Magnesian 
slate  which  overlies  this  last,  while  Professor  Dana  con- 
tinues to  cherish  the  contrary  opinion.  That  the  Sparry 
Lime-rock  is  not  only  younger  than  the  Stockbridge  or 
Lower  Taconic  limestone,  but  belongs  at  the  summit  of 
the  First  Graywacke,  had  been  clearly  pointed  out  by 
Eaton,  in  1832. 
§  160  A.    [In  an  ideal  section  given  in  1846  to  show 

*  Quar.  Jour.  (Jeol.  Soc,  xxxviii.,  397,  and,  in  abstract,  Amer.  Jour. 
Science,  xxiv.,  291. 


ji  M 


r- 


II 


i  h 


644 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


PL 


their  supposed  order  of  deposition,  Emmons  thus  arranges 
the  members  of  the  Taconic  system:  —  1.  Granular 
Quartz-rock ;  2.  Stockbridge  limestone ;  8.  Magnesian 
slate ;  4.  Sparry  limestone ;  5.  Roofing  slate ;  6.  Coarse 
sandstones ;  7.  Taconio  slate ;  8.  Black  slate.  In  a  com- 
panion section,  showing  the  apparent  succession  of  these 
in  the  Taconic  region,  from  east  to  west,  he  gives :  1.  2.  3, 
successive  alternations  of  the  Granular  Quartz-rock, 
Stockbridge  limestone,  and  Magnesian  slate;  4.  Sparry 
limestone,  followed  by  the  higher  members  already  noticed, 
and  unconforraably  overlaid  on  the  west  by  the  Loraine 
shales.  These  numbers,  5-8,  we  are  told,  "refer  to  the 
Taconic  slate  in  its  subordinate  beds."  *  This  name  of 
'*  Taconic  slate  "  was,  in  fact,  already  employed  by  Em- 
mons, in  1842,  to  designate  the  whole  group  of  strata  lying 
west  of  the  Sparry  Lime-rock,  and  between  it  and  the 
Loraine  shales  (^ante,  p.  586).  The  name  of  "Taconic 
schists,"  employed  by  Dana,  serves  only  to  confuse  his 
readers,  and  was  not  used  by  Emmons,  who  called  the 
schistose  strata  of  the  Lower  Taconic  simply  talcose  slate, 
or  Magnesian  slate,  and  gave  to  the  great  mass  oi  sedi- 
mentary strata  of  the  Upper  Taconic  the  collective  name 
of  the  Taconic  slate.  The  various  subdivisions  of  this 
Taconic  slate  group  are  given  by  Emmons  farther  on  (loc. 
cit.,  pp.  66-67)  as  coarse  greenish  sandstones,  gray  sand- 
stones, red  and  chocolate-colored  slates,  green  and  black 
flinty  slates,  blue  compact  limestones,  and  gray  silicious 
limestones,  all  of  them  lying  to  the  we^t  of  "  the  great 
mass  of  the  Sparry  limestone."  The  order  of  these  is 
variable,  and  the  observer  "  will,  in  the  space  of  fifteen  or 
twenty  miles,  pass  several  times  over  the  same  beds,  which 
are  brought  up  by  many  successive  uplifts "  with  a  seem- 
ing thickness  of  25,000  feet  (loc.  cit.,  p.  67).  The 
nature  of  these  movements  of  dislocation,  by  which  the 
subdivisions  of  the  Taconic  slates  are  thus  repeated,  is 
farther  shown  by  an  ideal  section  in  1855.  At  the  same 
•  Agriculture  of  New  York,  i.,  pp.  60-61. 


XL] 


THE  TACONIC  HISTORY  REVIEWED. 


645 


)GY.  l^'"'* 

thus  arranges 
^1.  Granular 

3.  Maguesiau 
ite ;  6.  Coarse 
,te.  In  a  com- 
ession  of  these 
3  gives :  !■  2.  o, 
r  Quartz-rock, 
ate;  4.  Sparry 
already  noticed, 

by  the  Loraine 
I,  "refer  to   the 
This  name  of 
aployed  by  Em- 
ip  of  strata  lying 
ween  it  and  the 
me  of  "Taconic 
y  to  confuse  his 
.   who  called  the 
nply  talcose  slate, 

eat  mass  ol  sedi- 

coUective  name 

^divisions  of  this 

iis  farther  on  (loc. 

stones,  gray  sand- 

,  green  and  black 
>nd  gray  silicious 

Lt  of  "the  great 

order  of  these  is 
space  of  fifteen  or 
5  same  beds,  which 

lifts"  with  a  seem- 
lit.,  p.  67).      The 
ion,  by  which  the 
thus  repeated,  is 
155.    At  the  same 
).  60-61. 


time  the  real  order  of  succession  in  the  Upper  Taconic 
was  declared  to  be,  —  greenish  chloritic  sandstones  at  the 
base,  followed  upward  by  a  great  mass  of  various  colored 
sUvtes  and  sandstones,  and,  towards  the  top,  by  the  Sparry 
limestone,  with  quartzose  and  conglomerate  beds,  black 
shaly  limestone,  and  fine  black  slates.* 

§  161.  [Nothing  of  all  tiiis  can  be  gathered  from 
Dana's  statements.  In  his  latest  communication  on  the 
subject,  read  to  the  American  Association  for  the  Ad- 
vancement of  Science,  in  August,  1885,f  he  refers  to 
Emmons's  description  of  the  Taconic  system  in  1855, 
wherein,  he  would  have  us  believe,  the  Sparry  Lime-rock 
is  made  a  part  of  the  Lower  Tacc^^ic.  By  referring 
thereto,!  we,  however,  find  it  to  consist  of:  A,  Granular 
Quartz-rock,  with  repeated  interstratifications  of  so-called 
talcose  slate ;  B,  Stockbridge  limestone,  and,  C,  overlying 
talcose  or  Magnesian  slate,  with  included  roofing-slate,  2000 
feet  thick.  These  "form  by  themselves  a  distinct  physical 
group,"  in  the  Taconic  range,  about  5000  feet  thick,  and 
Emmons  adds :  "  the  sequence  of  the  Lower  Taconic  rocks, 
which  has  been  stated  and  illustrated  in  the  foregoing 
pages,  is  essentially  the  same  from  Maine  to  Georgia." 
No  mention  is  there  made  of  "  the  Sparry  limestone,  with 
its  associated  slates,"  which  Dana  seems  to  say  are  included 
by  Emmons  in  his  Lower  Taconic,  and  the  only  apparent 
ground  for  this  interpolation  is  the  statement  of  Emmons 
that  the  Stockbridge  limestone  "  is  seamy  and  sparry,"  or, 
as  he  elsewhere  says,  "  occasionally  sparry,"  a  fact  which, 
he  tells  us,  had  led  others  to  mistake  it  for  the  Sparry 
limeatone  of  Eaton  (awie,  p.  585).  No  place  is  left  for 
the  Sparry  limestone  in  the  Lower  Taconic,  and  in  the 
Upper  Taconic  this,  as  well  as  the  other  limestone- 
masses  and  fossiliferous  slates,  is  placed  towards  the  sum- 
mit, and  not  at  the  base.    This  is  in  complete  accord  with 

•  American  Geology,  il.,  p.  49,  13. 

t  Amer.  Jour.  Science,  1886,  xxxi.,  p.  241. 

t  American  Geology,  ii.,  pp.  15-20. 


646 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


■'■■■{ 

11 

m,'  I 


:i:W 


the  remarkable  section  at  Quebec,  as  interpreted  by  Bill- 
ings and  myself,  as  well  as  by  James  Hall,  who,  in  1857, 
spoke  of  the  graptolitic  shales  of  that  vicinity  as  being 
near  the  Sparry  Lime-rock  of  Eaton,  towards  the  summit 
of  the  Hudson-River  group,  as  it  was  then  called  (^ante^ 
p.  587).  Tiie  horizon  of  this  was  declared  by  Billings 
to  be  considerably  higher  than  that  of  the  New  York  Cal- 
ciferous,  and  at  the  base  of  the  second  fauna  of  Barraude 
(aw^e,  p.  625).  The  recently  announced  discovery  by 
Messrs.  Ford  and  Dwight,  of  organic  forms,  believed  by 
them  to  be  of  Trenton  age,  in  the  Sparry  limestone  found 
in  the  Upper  Taconic  area,  in  Canaan,  New  York,*  is  only 
another  instance  of  the  fact,  so  often  insisted  upon  in 
these  pages,  of  the  recurrejice  of  Ordovician  strata  at 
many  points  along  this  great  Gray wacke  belt  from  Quebec 
to  Pennsylvania.] 

§  161  A.  [That  the  Sparry  limestone  was  regarded 
by  Emmons  as  related  to  the  Taconic  slate  group,  or  rather 
a  subordinate  part  thereof,  is  evident  from  his  descrip- 
tions in  1846.  After  noting  that  this  limestone,  while 
generally  persistent  in  its  extent  throughout  the  counties 
of  Dutchess,  Columbia,  Rensselaer,  and  Washington,  in 
New  York,  seems  in  parts  of  its  distribution  to  be  "en- 
gulfed, pinched  out,  or  lost,"  for  short  distances,  he 
farther  tells  us  that,  though  the  principal  mass  of  this 
limestone  occurs  on  the  eastern  border  of  the  Taconic 
slate  group,  similar  masses,  often  thinner,  are  found  farther 
westward  in  the  sections,  and  that,  while  some  of  these 
"  are,  undoubtedly,  mere  repetitions  of  the  same  mass  "  of 
Sparry  limestone,  others  are  distinct.  He  conjectures, 
therefore,  that  the  production  of  limestones  of  this  type 
"  occurred  at  intervals  during  the  whole  period  of  the  de- 
position of  the  Taconic  slate,"  thus  clearly  showing  that, 
in  his  opinion,  it  belongs  to  the  Taconic  slate  group  or 
Upper  Taconic,  and  not,  as  Dana  imagines,  to  the  Lower 
Taconic.  Emmons  at  the  same  time  informs  us  that  he 
*  Amer.  Jour.  Science,  1886,  zxxi.,  p.  240. 


XI.] 


THE  TACONIC   HISTORY  REVIEWED. 


647 


had  found  organic  remains  (including  trilobites  and 
graptolites)  in  three  of  the  subordinate  nienibors  of  tlie 
Taconio  shite  group,  namely,  the  green  sandstones,  the 
green  slates,  and  the  black  slates,  and  remarks,  with  regard 
to  the  Sparry  limestone,  "  no  fossils  have  yet  been  dis- 
covered in  this  rock,  though  it  must  be  confessed  sufficient 
examination  has  not  been  made  for  microscopic  bi- 
valves." * 

[The  conjecture  of  Emmons  as  to  the  recurrence  of  sim- 
ilar limestones  at  different  periods  during  the  deposition 
of  the  Taconic  slate  group  is  so  far  true  that  there  are 
many  bands  of  limestones,  both  pure  and  magnesian, 
among  the  shales  in  the  upper  portion  of  the  group. 
This  is  well  shown  in  the  section  at  Pointe  Levis,  near 
Quebec,  where  numerous  bands  of  this  kind  were  mapped 
by  Logan  in  1861.  Of  these  repeated  interstratifications 
of  pure  limestones,  dolomites,  sandstones,  and  argillaceous 
shales  of  Pointe  Levis  the  author  had  already  written 
in  1856:  "Both  limestones  and  dolomites  are  very 
irregular  and  interrupted  in  their  distribution,  the  beds 
sometimes  attaining  a  considerable  volume  while  at  other 
times  they  thin  out  or  are  replaced  by  sandstones."  Some 
of  these  were  then  described  as  forming  masses  many 
feet  in  thickness,  of  pure  limestone,  without  visible  marks 
of  stratification,  and  without  organic  remains,  and  were 
compared  to  travertines,  while  others  were  granular  and 
fossiliferous,  more  or  less  magnesian,  frequently  conglom- 
erate, and  passing  into  dolomites  and  dolomitic  sandstones. 
In  this  section  "other  organic  forms,  obscure  and  un- 
determined, occur  in  the  calcareous  beds  both  above  and 
below  "  the  belt  of  graptolitic  shales.f 

§  162.  The  different  views  with  regard  to  the  geolog- 
ical horizon  of  the  Lower  Taconic  or  Stockbridge  lime- 
stones of  Emmons  —  the  Granular  Lime-rock  of  Eaton  — 
may  be  resumed  as  follows :  — 

*  Agriculture  of  New  York,  vol.  I.,  pp.  68-74. 
t  Azoic  Rocks,  pp.  101-104,  106,  133. 


648 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


l|.« 

f^'^^m 

:^^4  ,■  ■ 

» '  .v^'HSfll^l 

^kjt 

^c^^^^tl 

1^ 

PI 
Iff 

5  ''   1 

4  (    ■ 

mam 
11 

I.  That  they  are  pre-Cambrian,  and  occupy  a  position 
below  the  Potsdam  sandstone  or  Red  Sand-rock,  and  the 
Quebec  group  of  Logan,  which  together  constitute  the 
First  or  Cambrian  Graywacke  of  Eaton  and  the  Upper 
Taconic  of  Emmons,  as  shown  in  the  table,  §  18.  (Eaton, 
Emmons,  Perry.  Marcou.) 

II.  That,  although  lying  beneath  the  greater  part  of 
this  Graywacke  series,  they  are  not  distinct  therefrom, 
but  are  the  altered  representative  of  the  Levis  limestone 
or  Sparry  Lime-rock,  imagined  by  Logan  to  lie  between 
the  Red  Sand-rock  below  and  the  chief  part  of  the  Quebec 
group  above.     (Logan,  in  his  geological  map  of  1866.) 

III.  That  they  are  the  altered  representatives  of  the 
whole  of  the  limestones  which,  in  the  New  York  system 
as  seen  in  the  Adirondack  area,  appear  between  the  Pots- 
dam sandstone  and  the  Utica  slate.  (Mather,  H.  D.  and 
W.  B.  Rogers,  J.  D.  Dana.) 

IV.  Allied  to  the  last  is  the  view  expressed  by  Wing, 
in  1875,  that  they  include  the  representatives  of  the  lime- 
stones of  the  Potsdam  and  Quebec  groups  of  Logan, 
together  with  the  Trenton  and  the  Loraine  or  Hudson- 
Ri^^er  group,  or,  in  other  words,  the  whole  of  the  Cham- 
plain  division  of  the  New  York  system,  from  the  Potsdam 
to  the  base  of  the  Oneida. 

V.  That  they  belong  to  a  horizon  above  the  Champlain 
division,  and  are  true  Silurian  and  Devonian.  (C.  B. 
Adams,  Ed.  Hitchcock,  W.  B.  Rogers.) 

§  163.  We  have  already  briefly  set  i'orth  the  arguments 
on  which  these  various  and  contradictory  hypotheses 
have  been  ?  ised.  While  the  fifth  supposes  the  Lower 
Taconic  limestone  to  hold  a  position  above  the  Oneida 
sandstone,  and  consequently  superior  to  the  Second  Gray- 
wacke, the  third  was  devised  at  a  time  before  the  existence 
of  the  First  Graywacke  (maintained  by  Eaton  and  Emmons, 
but  denied  by  Mather)  had  been  again  brought  into  favor 
uy  the  conversion  of  Logan  to  the  teaching  of  Emmons,  and 
by  his  farther  admission  that  the  Lower  Taconic  limestones 


iGY. 


CZX. 


XI.] 


THE  TACONIC  HISTORY  REVIEWED. 


649 


ipy  a  position 
■rock,  and  the 
jonstitute  the 
nd  the  Upper 
§  18.    (Eaton, 

rreater  part  of 
net  therefrom, 
.evis  limestone 
to  lie  between 
b  of  the  Quebec 
ap  of  1866.) 
ntatives  of  the 
sw  York  system 
tween  the  Pots- 
ither,  H.  D.  and 

ressed  by  Wing, 
ives  of  the  lime- 
•oups  of  Logan, 
aine  or  Hudson- 
le  of  the  Cham- 
■om  the  Potsdam 

the  Champlain 
svonian.     (C.  B. 

bh  the  arguments 
ftory  hypotheses 
Lses  the  Lower 
bove  the  Oneida 
Lhe  Second  Gray- 
fore  the  existence 
[ton  and  Emmons, 
[rought  into  favor 
Ig  of  Emmons,  and 
Faconic  limestones 


in  Vermont  and  Massachusetts  are  inferior  to  a  great 
mass  of  sandstones,  conglomerates,  and  shales  many  thou- 
sand feet  in  thickness,  constituting  what  he  called  the 
Lauzon  and  Sillery  divisions  of  the  Quebec  group. 

§  164.  It  was  not  until  after  his  change  of  view  as  to 
the  geological  horizon  of  this  great  sedimentary  or  Gray- 
wacke  series,  or,  in  other  words,  after  he  had  recognized 
the  fact  that  its  place  is  below  and  not  above  the  Trenton 
limestone,  that  Logan  began  to  examine  the  Lower  Taconic 
rocks  in  western  New  England.  Having  then,  by  a  mis- 
conception, placed  the  Levis  or  Sparry  Lime-rock  at  tho 
base  instead  of  the  summit  of  the  Graywacke,  and  still 
holding  to  the  notion  of  Mather  that  the  crystalline  rocks 
along  the  eastern  border  of  the  great  Appalachian  valley 
are  but  a  portion  of  the  paleozoic  strata  in  a  so-called 
metamorphic  condition,  Logan  was  led  to  look  upon  the 
Lower  Taconic  limestone  as  an  altered  representative  of 
the  Levis  limestone,  and  its  underlying  quartzite  as 
Potsdam  ;  the  immediately  overlying  schists,  and  the  suc- 
ceeding sandstones,  conglomerates,  and  shales  of  the  Gray- 
wacke series,  being  referred  to  the  Lauzor  and  Sillery 
divisions  of  his  Quebec  group.  Hence  the  wide  difference 
between  the  view  of  Logan,  given  under  IL,  and  that  of 
Mather  and  his  followers,  which  we  have  numbered  HI. 
While  both  would  place  the  Lower  Taconic  limestones 
above  the  Potsdam  and  below  the  Oneida,  Mather  imag- 
ined the  slates  and  sandstones  overlying  them  to  be  Ordo- 
vician  and  Silurian  (that  is,  Utica,  Loraine,  and  Oneida) 
or  the  Second  Graywacke  of  Eaton.  Logan,  on  the  other 
hand,  conceived  the  same  overlying  beds,  as  seen  by  him 
in  Vermont,  Massachusetts,  and  New  York,  to  belong  to 
the  Cambrian  or  First  Graywacke.  The  error  of  Mather 
and  of  H.  D.  Rogers  was  that  both  failed  to  recognize  the 
distinctness  of  this  great  series  of  sandstones,  conglomer- 
ates, and  slates,  which  are  so  conspicuous  in  the  Appala- 
chian valley,  and  confounded  them  with  the  Second  Gray- 
wacke.   This  error  it  was  which  completely  misled  the 


i 

r 

;| 

■' 

I 
1 

iti 

i 

■i' 
■  \ 

1 

1 

t 

5 

:J:! 

ti 

\ 

1 

1 

^lif 


650 


THE  TACONIO  QUESTION  IN  GEOLOGY. 


[XL 


'hi 

mm 


geological  survey  of  Canada  up  to  1861,  and  continues  to 
obscure  the  subject  in  the  minds  of  many  American  geo- 
logists to  the  present  time. 

§  165.  It  should  be  remembered  that,  as  already  pointed 
out  in  chapters  ii.  and  iii.,  the  overlying  Graywacke  or 
Upper  Taconic  does  not  include  the  schistose  rocks  imme- 
diately above  the  Lower  Taconic  limestone,  but  that  a 
considerable  amount  of  crystalline  schists  and  argillites 
occurs,  both  interstratified  with  and  overlying  this  lime- 
stone, and  forming  an  integral  part  of  the  Lower  Taconic 
series.  We  have,  moreover,  set  forth  in  chapter  v.  evi- 
uencfcs  of  the  distinction  between  the  Upper  and  Lower 
Taconic,  ax^d  have  shown  that  the  latter  is  not  limited  to 
the  great  Apptvlachian  valley,  which  confines  the  former, 
but  is  met  with  in  more  or  less  interrupted  belts  lying 
upon  the  crystalline  rocks  of  the  Atlantic  region  south 
and  east  of  the  great  valley,  from  New  Brunswick  to 
Georgia.  Thus  in  North  Carolina  not  less  than  four  dis- 
tinct and  separate  parallel  bands  of  the  Lower  Taconic 
are  met  with  between  that  of  the  great  v  illey  and  the 
overlying  tertiary  strata  of  the  coast,  while  similar  narrow 
bands  of  the  same  rocks  are  found  in  southern  New  York 
and  New  Jersey,  lying  upon  the  ancient  gneisses.  With 
none  of  these  Lower  Taconic  belts  outside  of  the  great 
valley,  so  far  ag  1^;  known,  is  the  Upper  Taconic  to  be 
found,  its  absence  being  due  either  to  erosion,  or,  more 
probably,  as  suggested  by  Emmons,  to  the  elevation  of 
these  areas  above  the  sea  during  Cambria',  time. 

§  166.  On  the  other  hand,  it  has  been  shown  in  chap- 
ter vi.  that  what  Mathev  regarded  as  a  continu<'.tion  of 
the  great  Graywacke  series  from  the  east  of  the  Hudson 
extends  south-westv; ard  across  Orange  County  and,  ac- 
cording to  Horton.,  there  rests,  with  a  high  eastern  dip,  on 
the  northwest  side  of  the  gneissic  belt  of  the  Highlands. 
From  central  "^'ermont,  northeastward  along  the  great 
valley,  to  the  St.  Lawrence  below  Quel^ec,  the  Lower 
Taconic  is  not  known,  and  the  Upper  Taconic  or  Gray- 


XI.] 


THE  TACONIO  HISTORY  REVIEWED. 


651 


iontin\ies  to 
lerican  geo- 

jady  pointed 

raywacke  or 
rocks  imme- 

,  but  tliat  a 

ind  avgilUtes 

ng  this  lirae- 

ower  Taconic 

tiapter  v.  evi- 

31  and  Lower 

aot  limited  to 

es  the  former, 

ed  belts  lying 

e  region  south 
Brunswick  to 
than  four  dis- 

Lower  Taconic 
V  lUey  and  the 

i  similar  narrow 

liern  New  York 
nieisses.  With 
de  of  the  great 
Taconic  to  be 
irosion,  or,  more 
ihe  elevation  of 

.  time. 

shown  in  chap- 
continu.'.tion  of 
of  the  Hudson 
County  and,  ac- 
]h  eastern  dip,  on 
I  the  Highlands, 
.along  the   gi-eat 
|el>ec,  the  Lower 
'aconic  or  Gray- 


waeke  series  rests  directly  upon  older  crystalline  schists, 
as  in  Orange  County,  New  York.  The  same  condition  of 
things  is  again  seen  in  Newfoundland.  These  facts, 
already  given  in  detail,  serve  to  show  the  distinctness  and 
independence  of  the  crystalline  Lower  Taconic  from  the 
uncrystalline  Upper  Taconic  or  Cambrian  series,  which 
two  were  probably  separated  by  a  considerable  interval  of 
time,  corresponding  to  the  stratigraphical  break,  long 
since  pointed  out  by  Eaton,  at  the  base  of  the  First  or 
Transition  Graywatjke. 

§  167.  The  student  wLo  refers  to  Dana's  paper  of  1882, 
already  noticed,  on  "The  Age  of  the  Taconic  System," 
will  obtain  no  light  on  the  question  of  this  Graywacke 
series,  nor,  indeed,  any  evidence  that  the  author  has  ever 
seriously  studied  the  literature  of  the  subject,  or  compre- 
hended its  relation  to  the  complex  problem  before  us. 
He  will  get  no  notion  of  the  two  opposing  vie'vs  as  to 
this  series  of  rocks,  or  its  position  as  above  or  below  the 
Trenton  limestone,  or  even  of  its  existence  as  a  great  suc- 
cession of  uncrystalline  sediments,  many  thousand  feet  in 
thickness,  and  distinct  from  the  Lower  '"^.aconic  limestones, 
as  maintained  alike  by  Eaton,  by  Emmons,  by  Mather, 
and  by  Logan,  and  as  set  forth  in  the  preceding  chapters. 

§  168.  The  hypothesis  of  Mather  and  H.  D.  Rogers  as 
to  the  Lovver  Taconic  rocks  was  devised  at  a  time  when 
the  progress  of  geology  in  New  York  had  made  known, 
in  the  Northern  district  of  that  State,  a  great  series  of 
nearly  horizontal  fossiliferous  strata  resting  upon  the  up- 
turned granitoid  gneiss  of  the  Adirondacks  and  includ- 
ing certaixi  familiar  subdivisions  of  the  paleozoic,  from 
the  Potsdam  sandstone  upwards.  The  relations  and  suc- 
cession of  these  various  rocks  were  simple  and  evident. 
To  the  east  and  southeast  of  this  region,  however,  beyond 
Lake  Champlain  and  the  Hudson  River,  there  were  found 
other  crystalline  rocks,  unlike  the  ancient  gneiss,  and  other 
uncrystalline  sediments  very  different  in  physical  character 
and  in  stratigraphical  attitude  from  the  paleozoic  strata  of 


^fil 


652 


THE  TACONIO  QUESTION  IN  GEOLOGY. 


[XL 


the  Northern  district  of  New  York.  The  question  then 
arose  as  to  the  correlation  of  these  unlike  rocks  in  the 
two  regions.  Amos  Eaton,  by  a  grand  generalization, 
had  already  arrived  at  a  system  of  classification  in  which 
he  recognized  the  existence  in  the  eastern  or  Appalachian 
region  of  types  of  Primitive  crystalline  rocks  other  than 
the  granitoid  gneiss,  and  of  great  masses  of  sedimentary 
strata  to  which  nothing  similar  was  found  in  the  contem- 
porary series  in  the  Adirondack  region. 

§  169.  Rejecting  the  teachings  of  Eaton,  and  falling 
back  on  the  metamorphic  doctrine,  which  was  then  so  gen- 
erally received,  Mather  maintained,  in  1843,  that  whatever 
to  the  east  of  the  Hudson  differed  lithologically  from  the 
ancient  gneiss,  on  the  one  hand,  and  from  the  paleozoic 
rocks  of  the  New  York  system,  as  seen  in  the  Adirondack 
region,  on  the  other,  could  be  nothing  else  than  these 
same  paleozoic  rocks  folded  and  subjected  to  successive 
stages  of  so-called  metamorphism,  as  seen  in  the  Lower 
Taconic  quartzites  and  marbles  and  the  crystalline  schists 
which  accompany  them,  as  well  as  those  others  that  succeed 
them  farther  to  the  east.  All  of  these  were,  according  to 
Mather,  nothing  but  the  more  or  less  altered  equivalents 
of  the  members  of  the  New  York  system,  from  the  Potsdam 
sandstone  to  the  Loraine  shales,  both  inclusive ;  while  the 
great  Graywacke  belt,  extending  along  the  east  side  of 
the  Hudson  from  Dutchess  County  northward  through 
Vermont  was  declared  to  be,  not,  as  maintained  by  Eaton, 
older  than  the  Trenton  limestone,  but  newer  than  the 
Loraine  shales. 

§  170.  The  considerations  which  lent  probability  to 
tliis  scheme  were,  first,  the  general  resemblance  of  this 
Graywacke  series  to  the  Oneida,  Clinton,  and  Medina 
subdivisions  of  the  New  York  s}  ^tem,  to  which  it  was  by 
Mather  referred ;  and,  secondly,  the  fact  that  the  argillites 
with  unctuous  schists,  granular  limestones,  and  granular 
quartzite,  which  he  agreed  with  Eaton  and  Emmons  in 
placing  below  the  adjacent  Graywacke,  presented  a  certain 


GY. 


XL] 


THE  TACONIO  HISTORY  REVIEWED. 


658 


question  then 
;  rocks  in  the 
generalization, 
ition  in  which 
r  Appalachian 
;ks  other  than 
)£  sedimentary 
in  the  contem- 

)n,  and  falling 
ras  then  so  gen- 
,,  that  whatever 
jically  from  the 
n  the  paleozoic 
the  Adirondack 
else  than  these 
id  to  successive 
n  in  the  Lower 
-ystalline  schists 
lers  that  succeed 
jre,  according  to 
jred  equivalents 
:om  the  Potsdam 
usive ;  while  the 
the  east  side  of 
thward  through 
.ained  by  Eaton, 
newer  than  the 

probability  to 

mblance  of  this 

;on,  and  Medina 

which  it  was  by 

_;hat  the  argillites 

les,  and  granular 

and  Emmons  in 

•esented  a  certain 


resemblance  to  the  Loraine  and  Utica  shales,  the  Trenton 
and  Chazy  limestones,  the  so-called  Calciferous  Sand-rock, 
and  the  underlying  Potsdam  sandstone.  This  general 
parallelism  from  the  top  of  the  Graywacke  downward, 
which,  to  the  mind  of  Eaton,  suggested  only  the  great  law 
of  cycles  in  sedimentation  (since  generally  recognized), 
was  accepted  by  H.  D.  Rogers  and  by  Mather  as  a  proof 
of  identity.  In  fact,  the  Lower  Taconic,  as  seen  along 
the  Appalachian  region,  in  its  regular  succession  of  gran- 
ular quartzites  with  granular  limestones  and  intervening 
and  overlying  soft  schists  and  argillites,  presents,  notwith- 
standing its  many  mineralogical  differences,  its  crystalline 
character,  and  its  great  thickness,  a  general  parallelism 
to  the  Champlain  division,  like  that  so  often  remarked  in 
groups  of  sedimentary  strata  at  very  various  geological 
horizons.  It  is  thus,  in  certain  respects,  more  like  the 
Adirondack  Cambrian  and  Ordovician,  with  which  it  has 
been  confounded,  than  their  Appalachian  representatives. 
These  resemblances  were  coupled  with  the  fact  that  along 
the  base  of  the  South  Mountain,  in  Pennsylvania,  this  suc- 
cession is  found  lying  between  the  ancient  granitoid  gneiss 
beneath,  and  the  Oneida  sandstone  above,  precisely  as  the 
Potsdam-Loraine  succession  in  northern  New  York  inter- 
venes between  the  same  gneiss  and  the  same  sandstone. 

§  171.  It  was  not,  therefore,  surprising  that  the  geolo- 
gists then  engaged  in  the  study  of  Pennsylvania,  New 
Jersey,  and  southern  New  York,  should  have  accepted 
this  plausible  and,  at  first  sight,  natural  explanation  of 
the  apparent  lithological  parallelism  presented  between 
these  regions  and  northern  New  York,  or  that  Mather 
endeavored  to  extend  it  to  the  rocks  east  of  the  Hudson. 
This  attempt  led  him  to  assign  to  the  great  G;aywacke 
series  which  we  now  know  to  be  of  Cambrxcin  age,  a 
position  above  the  Loraine  shales,  or,  in  other  words,  to 
thus  to  mistake  the  First  for  the  Second  Graywacke  of 
confound  it  with  the  Oneida,  Medina,  and  Clinton  subdi- 
visions of  northern  New  York  and  of  Pennsylvania,  and 


I     ,1 
if 

•   i 


I  -  ii  • 


654 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


CZI. 


m 

mm 

H 

mm 

fBBmBBsSB 

m 

Itfll 

Eaton,  and,  in  fact,  to  deny  the  existence  of  the  former  as 
a  great  series  lying  above  the  Lower  Taconic  and  below 
the  horizon  of  the  Trenton  limestone.  The  two  brothers 
Rogers,  with  Mather,  forty  years  since,  reasoning  from  the 
paleozoic  succession  as  displayed  in  the  Adirondack  area, 
were  not  prepared  to  admit  that,  in  a  region  so  near  as 
the  great  Appalachian  valley,  the  paleozoic  sediments 
beneath  the  Trenton  horizon  could  assume  a  type  so 
unlike  the  well  known  Potsdam  and  Calciferous  subdivis- 
ions of  the  Northern  district  of  New  York,  or  that  these 
subdivisions  could  be  represented  in  the  Appalachian  area 
by  the  vast  and  lithologically  unlike  series  of  the  First 
Graywacke,  which  Eaton  had  already,  ten  years  before, 
assigned  to  its  true  position  below  the  horizon  of  the 
Trenton  limestone.  Hence  came  the  great  mistake  in 
American  stratigraphy,  the  denial  by  Mather  and  his 
followers  of  the  distinctness  of  the  First  Graywacke  of 
Eaton,  and  the  assertion  of  its  identity  with  the  Second 
Graywacke  of  the  same  author.  So  long  as  this  false 
position  was  maintained,  there  was  a  plausible  argument 
to  be  made  for  the  original  hypothesis  of  the  brothers 
Rogers  and  Mather  as  to  the  age  of  the  Lower  Taconic 
series ;  but  with  the  recognition  of  the  correctness  of 
Eaton's  view  of  the  First  Graywacke,  the  fallacy  of  this 
hypothesis  became  obvious,  and  those  who  would  still 
advocate  it  can  only  do  so  by  rejecting  the  results  alike  of 
stratigraphical  and  paleontological  study  for  the  last  gen- 
eration. 

IX.  —  THE  METAMORPHIC  HYPOTHESIS. 

§  172.  The  absence  from  the  granular  quartz-rock,  the 
granular  marbles  and  their  intercalated  and  conformably 
overlying  schists  and  argillites  of  the  Lower  Taconic 
series,  of  the  organic  remains  of  the  various  members  of  the 
Champlain  division,  or,  indeed,  of  any  organic  form  save 
the  peculiar  Scolithus  of  the  granular  quartz-rock  already 
noticed  (§  23),  was  explained  by  those  who  maintained 


the  former  as 
c  and  below 
two  brothers 
ling  from  the 
L-ondack  area, 
on  so  near  as 
)ic   sediments 
ne  a  type  so 
irons  subdivis- 
or  that  these 
palachian  area 
8  of  the  First 
.  years  before, 
lorizon  of  the 
;at  mistake  in 
ather  and  his 
Graywacke  of 
ith  the  Second 
g  as  this  false 
sible  argument 
»f  the  brothers 
Lower  Taconic 
correctness  of 
fallacy  of  this 
'ho  would  still 
results  alike  of 
lor  the  last  gen- 

Ihesis. 

luartz-rock,  the 
id  conformably 
^ower  Taconic 
I  members  of  the 
Irani  c  form  save 
rtz-rock  already 
^ho  maintained 


xi.i 


THE  METAMORPHIC   HYPOTHESIS. 


655 


the  paleozoic  age  of  the  series  by  the  convenient  hypoth- 
esis of  a  chemical  change,  attended  by  crystallization  or 
so-called  metamorphism,  which  was  supposed  to  have 
effaced  the  original  characters  of  the  sediments,  and  oblit- 
erated their  organic  remains.  In  accordance  with  this 
hypothesis,  it  was  believed  that  great  series  of  strata 
might,  within  short  distances,  assume  a  new  aspect,  not 
through  any  original  differences  in  the  sediments,  but 
from  transformations  wrought  in  these  after  deposition, 
in  virtue  of  which  fossiliferous  and  earthy  limestones, 
losing  all  traces  of  their  organic  remains,  could  be  con- 
verted into  granular  limestones  containing,  instead,  only 
crystalline  silicates  —  while  ordinary  sandstones  and  argil- 
lites  might  become  micaceous,  chloritic,  or  hornblendio 
schists,  and  even  gneisses  and  granite-like  rocks. 

§  173.  These  views,  a  development  of  the  Huttonian 
school  in  geology,  were,  as  is  well  known  to  students, 
accepted  a  generation  since  by  a  large  number  of  geolo- 
gists, both  in  Europe  and  America,  and  were  carried  to 
an  extreme  in  America.  Mather,  in  his  final  renort  on  the 
geology  of  the  Southern  district  of  New  Yor..,  declared 
that  "  the  Taconic  rocks  are  of  the  same  age  with  those 
of  the  Champlain  division,  but  modified  by  metamorphic 
agency  and  by  the  intrusion  of  plutonic  rocks."  They 
were,  however,  designated  by  him  as  "  imperfectly  Meta- 
morphic rocks,"  while  the  various  crystalline  schists  of 
New  York  and  western  New  England,  included  by  him  in 
his  group  of  proper  Metamorphic  rocks,  were  declared  to 
be  the  same  series  in  a  still  more  highly  altered  condition 
(§  121).  Respecting  these,  he  asserted  that  where  the 
Taconic  and  Metamorphic  rocks  come  together,  "  no  well 
marked  line  of  distinction  can  be  drawn,  as  they  pass  into 
each  other  by  insensible  shades  of  difference."  Mather 
was  disposed  to  admit,  in  addition  to  these,  an  older  or 
so-called  Primary  series  of  crystalline  rocks  in  the  High- 
lands of  the  Hudson,  but,  in  the  course  of  his  report, 
ended  by  declaring  that  the  Primary  limestones  of  south- 


656 


THE  TACONIO  QUESTION  IN  GEOLOGY. 


[XL 


em  New  York  and  northern  New  Jersey,  with  their  asso- 
ciated granitic  and  hornblendic  rocks,  were  nothing  more 
than  modifications  of  the  members  of  the  Champlain  divis- 
ion. He  had  been  led  to  believe  that  the  Primary  lime- 
stones in  question  "  can  be  easily  traced  through  all  the 
changes  from  a  fossiliferous  to  a  crystalline  white  lime- 
stone, containing  crystallized  minerals  and  plumbago." 
From  the  interstratification  of  these  crystalline  lime- 
stones, supposed  by  him  to  be  paleozoic,  with  gneissic  and 
hornblendic  rocks,  he  was  brought  to  maintain  the  paleo- 
zoic age  of  these,  and  thus  to  doubt  whether  a  portion,  at 
least,  of  what  he  had  called  Primary  gneiss  was  not  also 
paleozoic. 

§  174.  Apart  from  the  crystalline  rocks  of  the  High- 
land or  South  Mountain  belt,  whose  primary  character 
was  in  part  questioned  by  Mather,  the  great  area  of  crys- 
talline rocks  lying  to  the  south  and  east  of  this  range  in 
New  York,  comprising  those  of  Westchester  and  New 
York  Counties,  and  embracing  Manhattan  Island,  was  by 
him  included,  with  the  adjacent  rocks  of  western  New 
England,  in  his  Metamorphic  series,  and  declared  to  be 
"nothing  more  than  the  rocks  of  the  Champlain  division, 
modified  greatly  by  metamorphic  agencies  and  by  the 
intrusion  of  granitic  and  trappean  aggregates."  In  this 
area  of  southern  New  York  he  noticed  hornblendic  rocks, 
gneiss,  mica-schists,  and  crystalline  limestones,  besides 
granite,  syenite,  and  serpentine,  the  latter  three  being 
regarded  by  him  as  intrusive  rocks.* 

§  175.  The  doctrine  of  the  Metamorphic  school  of  forty 
years  since,  as  then  resumed  and  formulated  by  Mather, 
was  briefly  as  follows:  The  different  groups  of  crystal- 
line stratified  rocks  in  southeastern  New  York  and  west- 
ern New  England  (with  the  doubtful  exception  of  the 


♦Tor  the  details  of  these  views  see  Mather's  Geology  of  the  Southern 
District  of  New  York,  1843,  paaaim.  A  summary  of  Mather's  somewhat 
diffuse  statements  will  be  found  in  the  author's  volume  on  Azoic  Bocks, 
pp,  38-42. 


Y. 


[XI. 


XI.] 


THE  METAMORPHIC   HYPOTHESIS. 


657 


1  their  asso- 
)thing  more 
nplain  divis- 
limary  linie- 
3Ugh  all  the 
white  lime- 
plumbago." 
talline    lime- 
i  gneissic  and 
in  the  paleo- 
•  a  portion,  at 
was  not  also 

of  the  High- 
lary  character 
,  area  of  crys- 
this  range  in 
3ter  and  New 
Jsland,  was  by 
western  New 
ieclared  to  be 
plain  division, 
a  and  by  the 
es."     In  this 
blendio  rocks, 
tones,  besides 
r  three  being 

school  of  forty 
ed  by  Mather, 
ups  of  crystal- 
ork  andwest- 
ception  of  the 

.y  of  the  Southern 
-lather's  somewhat 
le  on  Azoic  Rocks, 


gneissic  belt  which  he  had  designated  Primary),  including 
the  Lower  Taconic  series,  the  series  of  micaceous  gneisses 
and  mica-schists,  as  well  as  the  massive  granitoid  and 
hornblendio  gneisses  with  tlieir  crystalline  limestones,  all 
belong  to  one  and  the  same  geological  period,  and  are 
contemporaneous  in  age  with  tb^  paleozoic  rocks  of  the 
Champlain  division  of  northern  ^low  York,  from  the  Pots- 
dam sandstone  to  the  Loraine  shales,  both  inclusive. 
These  various  and  unlike,  though  coiitiguous  groups  of 
crystalline  rocks  were,  according  to  Mather,  all  produced 
from  the  same  uncrystalline  Cambrian  and  Ordovician 
sediments,  through  a  mysterious  process  of  transforma- 
tion, by  what  he  called  "  metamorphic  agencies,"  and  the 
intrusion  of  igneous  rocks,  in  which  category  he  included 
not  only  the  interbedded  serpentines,  but  apparently, 
under  the  name  of  granites,  much  of  the  granitic  gneiss, 
which  characterizes  large  areas  of  the  region,  as  well  as 
the  abundant  endogenous  granitic  veins,  —  true  intrusive 
or  exotic  granites  being  rare  in  the  region.  In  Mather's 
cosmogony  there  was  nothing  in  the  geological  sequence, 
at  least  in  northeastern  America,  between  the  New  York 
paleozoic  series,  as  seen  in  the  Adirondack  area,  and  the 
fundamental  Laurentian  gneiss  which  there  underlies  it. 
Consequently  all  crystalline  rocks  which  could  not  be 
referred  to  the  latter  were,  unless  plutonic,  the  result  of 
some  unexplained  transformation  of  this  lower  part  (ji.  the 
paleozoic  column,  known  as  the  Champlain  division. 

§  176.  This  hypothesis,  extravagant  as  it  now  seems, 
was,  during  the  next  few  years,  accepted  by  many  geolog- 
ical students  on  the  authority  of  Mather  and  the  brothers 
H.  D.  and  W.  B.  Rogers.  These  latter,  in  1846,  extended 
this  view  of  Mather  to  the  White  Mountains  of  New 
Hampshire,  and  suggested  that  the  gneissic,  hornblendic, 
and  micaceous  rocks  of  this  series,  since  named  Montal- 
ban,  instead  of  belonging,  as  hitherto  believed,  to  the 
"so-called  Primary  periods  of  geological  time,"  were  prob- 
ably altered  paleozoic  strata  of  Silurian  age,  including  the 


I 


..m,  ^ 


^1'i|' 


M  n 


>(ii 


; :  1' 


ill  ! 


058 


THE  TACONIC  QUESTION   IN  OEOLOOV. 


IXI. 


Oiiekla,  Medina,  and  Clinton  subdivisions  of  tho  New 
Yorlc  system.  These  observers  then  proceeded  to  name 
many  species  f)f  characteristic  organic  forms  of  the  Silu- 
rian i)eriod,  'which  they  thought  to  recognize  in  certain 
crystalline  aggregates  in  the  mica-schists  of  the  region. 
In  1847,  however,  the  same  observers  announced  that 
they  no  longer  considered  these  forms  of  organic  origin,  * 
and,  while  they  did  not  then  formally  retract  their  opin- 
ion as  to  the  paleozoic  ago  of  tho  gneisses  and  mica-schists 
of  the  White  Mountains,  are  known,  from  their  subse- 
quent writings,  to  have  abandoned  it  as  unfounded, 
although  it  was  for  some  years  afterward  maintained, 
with  some  variations,  by  Logan,  Lesley,  and  the  present 
writer.! 

§  177.  As  regards  the  ancient  crystalline  series  of  the 
Highlands  of  the  Hudson  and  of  New  Jersey,  which 
differs  in  lithological  characters  from  the  last,  we  find 
that  H.  D.  Rogers,  while  he  did  not  accept  the  notion  of 
Nuttall  and  of  Mather  that  its  gneisses  are  altered  paleo- 
zoic sediments,  im"  'fined  the  crystalline  limestones,  whicli 
are  really  interstratified  with  them,  to  be  portions  of  a 
younger  limestone,  altered  by  supposed  igneous  agencies. 
In  the  words  of  Lesley,  Rogers,  while  maintaining  the 
Primary  age  of  the  Highland  gneisses,  "  mistook  the  crys- 
talline limestone  engaged  among  the  Highlands  for  meta- 
morphosed synclinal  outliers  of  No.  II.,  as  at  Franklin,"  in 
New  Jersey,  whereas  Cook  has  since  shown  that  the  hori- 
zontal strata  of  this  later  period  overlie  the  upturned 
crystalline  limestones  of  Franklin.:):  As  a  consequence 
of  this,  H.  D.  Rogers  was  quoted  by  Mather  as  support- 
ing the  extreme  notions  of  metamorphism  maintained  l)v 
Nuttall  in  1824,  which  Mather  himself  accepted,  and 
which,  as  I  have  elsewhere  said,  "  were  adopted  by  H.  D. 

*Amer.  Jour.  Science  [2],  L,  411,  and  v.,  116. 

t  See,  for  historical  notes.  Hunt,  Amer.  Jour.  Science,  vol.  1.,  84;  also 
Azoic  Rocks,  pp.  62,  181,  182. 

X  Lesley,  Amer.  Jour.  Science,  1865,  xxxix.,  222. 


QY. 


ixi. 


XI.] 


THE  METAMORPHIC    HVPOTIIESIS. 


O.V.) 


II ; 


of  the  New 
iiled  to  name 
J  of  t\ie  Silu- 
ize  iu  certain 
)f  the  region, 
uounced  that 
ganic  origin,* 
vet  thoir  opin- 
iid  mica-schists 
xn  their  suhse- 
as  unfounded, 
rd  maintained, 
,nd  the  present 

ne  series  of  the 
'   Jersey,  which 
^e  last,  we  find 
pt  the  notion  of 
re  altered  paleo- 
imestones,  which 
he  portions  of  a 
gueous  agencies, 
'maintaining  the 
mistook  the  crys- 
[hlands  for  nieta- 
i  at  Franklin,"  iu 
^vn  that  the  hovi- 
[ie  the   upturned 
u  a  consequence 
[ather  as  support- 
Im  maintained  V)y 
klf  accepted,  and 
\dopted  by  H.  D. 


IciencC; 


vol.1..  84;  also 


R«)gers,  as  far  as  regards  the  crystalline  limestones  of  the 
Highlands  in  New  Jersey,"* — while  he  soon  after  ap- 
plied the  same  doctrine,  in  its  fullest  extent,  to  the  great 
gneissic  series  of  the  White  Mountains. 

§  178.  To  sum  up  in  a  few  words  the  views  of  the 
Metamorphic  school  forty  years  since  (1840-184(3),  we 
find  that  11.  I),  and  W.  B.  Rogers  then  maintained  the 
paleozoic  age  of  the  Lower  Taconic  series,  of  the  White 
Mountain  gneisses  and  mica-schists,  and  also  of  the  crys- 
talline limestones  found  among  the  gneisses  of  the  New 
York  and  New  Jersey  Highlands,  though  admitting  the 
primary  age  of  these  Highland  gneisses.  Mather,  again, 
while  holding,  in  like  manner,  to  the  paleozoic  age  of  the 
Lower  Taconic,  was  not  acquainted  with  the  White 
Mountain  series,  but  maintained  that  the  whole  o'"  the 
gneisses,  mica-schists,  and  crystalline  limestones  of  south- 
eastern New  York,  with  the  possible  exception  of  the 
Highland  belt,  were  paleozoic,  and  of  one  age  with  the 
Taconic  series.  It  is  worthy  of  note  that  on  the  geologi- 
cal map  of  the  State  of  New  York,  published  in  1842,  ''by 
legislative  authority,"  of  which  the  Southern  district  was 
prepared  by  Mather  himself,  there  is  no  distinction  of 
color  between  the  gneissic  rocks  of  the  Highlands  and 
those  adjacent  to  them  on  the  south  and  east,  described 
by  him  in  his  final  report,  in  the  following  year,  as  meta- 
morphic paleozoic  strata.  The  serpentine  of  the  region, 
as  seen  in  Staten  Island,  is  colored  on  the  map  like  the 
adjacent  intrusive  triassic  diabase,!  but  no  attempt  is 
there  made  to  designate  other  eruptive  rocks  than  these. 

§  179.  In  opposition  to  the  views  of  this  Metamorphic 
school,  there  were  not  wanting  some,  like  Emmons  and 
Charles  T.  Jackson,  who  maintained  the  Primitive  age  of 
the  whole,  or  a  part,  of  these  crystalline  rocks  of  New 
England,  though  recognizing,  as  Eaton  had  done,  their 

*  Hunt,  Azoic  Rocks,  p.  41. 

t  See,  for  details  witli  regard  to  this  and  the  other  serpentines  of  the 
region,  ante,  pp.  435-442. 


iU 


1 1 


III, , 

I..      .  ,  ^h 


I 


II  'i 


Ih 


6(30 


THE  TACONIC  QUI«TtON  IN  QEOLOCJY. 


[XL 


lithological  distinctness  from  the  gneiss  of  the  Adiron- 
ducks  and  of  the  Ilighhinds  of  the  Iludsun.  Already, 
moreover,  in  1824,  Bigsby  had  discovered,  around  Luke 
Superior  and  beyond,  the  existence  of  two  series  of  crys- 
tal lino  rocks,  and  distinguished  the  younger  of  these  as 
beh)nging  to  the  Transition  series.  More  than  twenty 
years  hiter,  the  geoh)gical  survey  of  Canada,  while  adopt- 
ing for  the  crystalline  rocks  of  New  England,  and  their 
extension  into  ('anada,  the  hypothesis  of  their  i)aleozoic 
age,  re-examined  these  Transition  crystalline  schists  of 
Bigsby,  as  seen  both  on  Lakes  Superior  and  Huron,  and 
on  the  upper  Ottawa,  and  described  them  as  forming  a 
distinct  group  between  the  base  of  the  paleozoic  series 
and  the  ancient  gneiss,  upon  which  it  was  found  to  rest 
unconformably.  This  intermediate  series,  first  described 
in  1847,  was  by  the  present  writer  designated,  in  1855,  by 
the  name  of  ;iuronian,  —  the  underlying  gneissio  series 
having,  in  1854,  received  the  name  of  Laurontian.  With 
the  Huronian,  as  we  have  endeavored  to  show  (^ante,  pp. 
414,  581),  have  since  been  included,  in  the  region  of  the 
great  lakes  and  elsewhere,  areas  of  Taconian  rocks. 

§  180.  In  1858  appeared  the  final  Report  of  H.  D. 
Rogers  on  the  geology  of  Pennsylvania,  in  which  we  find 
no  recognition  of  the  extreme  doctrines  of  metamorphism 
maintained  by  Mather  in  1843,  and  by  W.  B.  Rogers  and 
himself  in  1846.  Not  having  come  to  an  understanding 
of  the  question  of  the  P'irst  Graywacke,  H.  D.  Rogers 
regarded  the  Lower  Taconic  series  in  Pennsylvania  as  an 
altered  form  of  the  Champlain  division,  and  considered 
the  granular  quartz-rock  with  Scolithus  to  be  the  equiva- 
lent of  the  New  York  Potsdam  sandstone.*  The  charac- 
teristic crystalline  rocks  of  western  New  England  and 
southeastern  New  York,  described  by  Mather  as  altered 
paleozoic,  pass  beneath  the  mesozoic  sandstone  in  New 

*  For  Lesley's  doubts  as  to  the  precise  equivalence  of  the  Primal 
quartzite  of  Pennsylvania  and  the  New  York  Potsdam,  see  Aiuer.  Jour. 
Science,  18d5,  xxxix.,  223. 


I 


Y. 


pa. 


the  AtUron- 

IX.     Alremly, 

wound  Lake 

nieft  of  cvys- 

i-  of  tliese  as 

than  twenty 
while  tttlopt- 

ind,  and  then- 

lieir  paleozoic 

ine  sciiista  of 

id  Huron,  and 

I  as  forming  a 

,aleozoic  series 
found  to  rest 

first  described 

;etl,  in  1855,  by 
gneissio  series 

rentian.     With 

show  iante,  pp. 

le  region  of  the 

^an  rocks, 
iport  of  H.  D. 
which  we  find 
metamorphism 
B.  Rogers  and 
understanding 
„  H.  D.  Rogers 
nsylvania  as  an 
and  considered 
be  the  equiva- 
,  *     The  charac- 
w  England  and 
lather  as  altered 
ndstone  in  New 

Lnce  of  the  Trimal 
kam,  see  Aiuer.  Jour. 


XL] 


THE  METAMOIIPHIC    HVPOTHK8I8. 


fiOl 


Jersey  and  re-appear  in  sontheastern  Pennsylvania.  Those 
rocks  were  now,  in  1858,  describeil  by  II.  1).  Ilogcis  us 
forming  two  greiit  gronps,  an  older  or  so-called  llvjinzoio 
gneiss  system,  and  a  younger  one  of  crystalline  scliists, 
which  he  called  Azoic  and  placed  beneath  the  horizon  of 
the  Scolithus  sandstone.  The  views  of  H.  D.  Rogers,  in 
1858,  with  r»'gard  to  the  crystalline  rocks  of  the  Atlantic 
belt,  were  thns,  as  I  have  elsewhere  said,  "a  retnrn  to 
those  held  by  Eaton  and  by  Emmons,  but  were  in  direct 
02)position  to  that  maintained  by  Mather,  which  bad  been 
adopted  at  that  time  by  Logan  and  by  the  jjresent  writer" 
(ante,  p.  40G),  and,  so  far  as  regards  the  White  Moun- 
tains, were  nuiintained  by  the  Messrs.  Rogers  themselves, 
in  1846. 

§  181.  Henry  D.  Rogers  died  in  1867,  but  his  venera- 
ble brother,  William  li.  Rogers,  survived  till  1882,  and 
fully  shared  the  views  set  forth  by  the  former  in  1858,  as 
to  the  pre-paleozo'ic  age  of  the  great  groups  of  crystalline 
rocks.  His  careful  and  extended  studies  in  Virginia  dur- 
ing many  years  had  convinced  him  of  the  fallacy  of  the 
metamorphic  hypothesis  of  Mather.  In  a  sketch  of  the 
geology  of  that  state,  contributed  by  him  as  late  as  1878 
to  James  Macfarlane's  "Geological  Railroad  Guide," 
Rogers  makes  it  plain  that  the  crystalline  rocks  of  tliat 
region  are  all  pre-paleozoic,  and  older  than  what  he  calls 
the  Primal  or  Potsdam  group.  This  he  describes  as  lying 
on  the  western  slope,  and  in  the  west-flanking  hills  of  the 
Blue  Ridge,  "  often  by  inversion  dipping  to  the  southeast, 
in  seeming  conformity,  beneath  the  older  rocks  of  the 
Blue  Ridge,  but  often,  also,  resting  unconformably  upon 
or  against  them."  These  older  rocks,  he  tells  us,  "com- 
prise masses  referable  probably  to  Huronian  and  Lauren- 
tian  age,"  and,  farther,  he  informs  us  that  the  letters,  A, 
B,  C,  and  D,  used  in  his  tabular  view,  "  mark  four  rather 
distinct  groups  of  Archean  rocks  found  in  Virginia,  of 
which  the  first  three  may  probably  be  referred  to  the 
Laureutian,   Huronian,   and    Montalban   periods,   respec- 


n 


it: 


662 


THE  TACONIC  QUESTION   IN  GEOLOGY. 


IXI. 


tively,  and  the  fourth  to  an  intermediate  stage,  —  the 
Norian  or  Upper  Laurentian." 

§  182.  It  should  here  be  remarked  that  this  Primal 
group  of  the  valley  of  Virginia,  also  called  by  Rogers 
Lower  Cambrian,  is  no  other  than  the  base  of  the  Lower 
Taconic  series,  which  he  continued  to  regard  as  in  some 
sense  the  representative  of  the  Cambrian  Potsdam  of  the 
Adirondack  region.  Li  this  connection,  as  showing  the 
relations  of  this  group  to  the  crystalline  rocks,  and  the 
apparent  inverted  succession,  I  venture  to  make  the  fol- 
lowing extracts  from  a  letter  from  W.  B.  Rogers,  written 
to  me  in  1877,  for  publication  in  the  volume  on  Azoic 
Rocks,  after  an  examination  with  him  of  some  forty 
unpublished  transverse  sections,  made  across  the  Blue 
Ridge  during  his  geological  survey  of  Virginia.  In  many 
of  these  sections  "  illustrating  the  position  of  the  Lower 
Cambrian  (our  Primal  conglomerate,  etc.),  in  their  con- 
tact with  the  crystalline  and  metamorphic  rocks  of  the 
Blue  Ridge  in  Virginia,"  "  the  unconformity  of  the  Cam- 
brian upon  and  against  these  crystalline  and  metamor- 
phic rocks  is  unmistakable  and  conspicuous;  the  lower 
members  of  the  Primal  being  seen  to  rest  upon  the  slope 
of  the  Ridge,  with  northwest  uiidulating  dips,  on  the 
edges  of  the  steeply  southeastward-dipping  older  rocks.  lu 
other  cases,  the  Primal  beds,  thrown  into  southeast  dips 
in  the  hills  which  flank  the  Blue  Ridge,  are  made  to 
underlie,  with  more  or  less  approximation  to  conformity, 
the  older  rocks  forming  the  central  mass  of  the  mountain." 
Here  follow  details  aa  to  localities,  for  which  the  reader 
is  referred  to  the  letter  as  published.  * 

§  183.  While,  therefore,  tlie  brothers  Rogers  held,  and 
odiers  still  hold,  to  the  paleozoic  age  of  the  Lower 
Taconic  rocks,  the  view  put  forward  by  Mather,  that  the 
great  region  of  gneisses  and  crystalline  schists  with  lime- 
stones, lying  to  tiie  east  of  these,  consists  of  more  highly 
altered  paleozoic  strata,  had  become  discredited.     It  was, 

'  *  Hunt,  Azoic  liocks,  p.  198. 


•GY. 


IXI. 


XI.] 


THE   METAMORPHIC   HYPOTHESIS. 


663 


stage,  —  the 

t  this  Primal 
ed  by  Rogers 
of  the  Lower 
rd  as  in  some 
otsdam  of  the 
s  showing  the 
rocks,  and  the 
make  the  fol- 
Rogers,  written 
lume  on  Azoic 
of  some   forty- 
cross  the   Blue 
rinia.    In  many 
n  of  the  Lower 
.),  in  their  con- 
YLG  rocks  of  the 
lity  of  the  Cam- 
e  and  metamor- 
,ous;  the  lower 
upon  the  slope 
g   dips,  on   the 
older  rocks.    In 
,  southeast  dips 
re,  are  made  to 
fi  to  conformity, 
if  the  mountain." 
vhich  the  reader 

JRogers  held,  and 

of    the    Lower 

("Mather,  that  the 

schists  with  \wc- 

of  more  highly 

n-edited.    It  was, 


as  we  have  seen,  abandoned  by  H.  D.  Rogers  for  Pennsyl- 
vania, in  1858,  and  by  W.  B.  Rogers  for  Virginia,  where 
he  recognized  in  the  pre-Taconian  rocks  the  same  great 
divisions  which  I  had  elsewhere  pointed  out.  The  history 
of  the  studies  of  Tlionias  Macfarlane,  ard  my  own,  wliich 
showed  conclusively  the  pre-paleozoic  age  of  the  exten- 
sion of  the  New  England  crystalline  schists  i'.ito  the 
Province  of  Quebec,  has  already  been  told  elsewhere.* 

§  184.  It  was,  therefore,  with  some  surprise  that  geo- 
logical stu'.lents  found  J.  D.  Dana,  in  1880,  attemi)ting  to 
resuscitate,  in  its  completeness,  the  discarded  view  of 
Mather.  In  an  elaborate  paper  on  "  Tlie  Geological  Rela- 
tions of  the  Limestone  Belts  of  Westchester  County,  New 
York,"  which  appeared  that  year,  Dana,  following  up  the 
reasoning  already  noticed  (§  161),  by  which  he  sought  to 
sustain  the  paleozoic  age  of  the  Lower  Taconic  rocks, 
proceeds  to  assume  that  the  crystalline  marbles  enclosed 
in  the  gneisses,  as  well  as  the  gneisses  and  crystalline 
schists  of  the  region  named,  are  altered  rocks  of  paleozoic 
age.  To  quote  his  conclusions :  "  The  limestone  of  West- 
chester County  and  of  New  York  Island,  and  the  con- 
formably associated  metamorphic  rocks,  are  of  Lower 
Silurian  age,"  and,  farther,  "  the  limestone  and  the  con- 
formably associated  rocks  of  the  Green  Mountain  region, 
from  Vermont  to  New  York  Island,  are  of  Lower  Silurian 
age."  f  His  argument  in  favor  of  these  assumptions 
appears  to  be,  briefly,  this :  —  That  the  crystalline  lime- 
stones of  the  gneissic  series,  the  granular  Lower  Taconic 
marbles,  and  the  fossiliferous  Cambrian  and  Ordovician 
limestones  found  among  the  uncrystalline  sediments  of 
the  Appalachian  valley,  along  the  western  flank  of  the 
crystalline  helt  north  of  the  Highlands,  are  but  three  dif- 
ferent conditions  of  one  and  the  same  calcareous  series, 
and,  lience,  that  the  great  area  of  crystalline  rocks  south 
of   the    narrow   range    of  the    Highlands    (of  which   ho 

*  Hunt,  Azoic  Rocks,  pp.  182-188,  and  ante,  pp.  406,  407. 
t  Amer.  Jour.  Science,  18S0,  xx.,  455. 


664 


THE  TACONIC  QUESTION   IN  GEOLOGY. 


[XI. 


Vif'" 


admits  the  eozoic  age)  consists  of  paleozoic  strata,  Cam- 
brian or  Ordovician  in  age. 

§  185.  Dana,  having  announced  his  conclusions  as 
above,  adds :  "  The  evidence  which  has  been  adduced, 
though  then  but  partly  discerned,  led  Profs.  W.  B.  and 
K,  D.  Rogers,  and  Prof.  W.  W.  Mather,  nearly  to  i:.e 
results  here  reached."  In  support  of  this  assertion,  he 
refers  to  Mather's  report  of  1843,  in  which,  as  we  have 
seen,  the  hypothesis  was  advanced,  and  also  under  the 
head  of  "  Professors  Rogers,"  to  a  paper  by  them  in  1841, 
in  the  Proceedings  of  the  American  Philosophical  Society. 
as  well  as  to  a  statement  in  the  American  Journal  of 
Science  for  1872  (vol.  iv.,  p.age  363).  Tliis  the  reader 
will  find  to  be  nothing  more  than  Dana's  assertion  that 
the  Messrs.  Rogers,  in  that  same  paper  of  1841,  main- 
tained the  Champlain  age  of  the  Lower  Taconic  series,  — 
a  view  which,  as  we  all  are  aware,  one  of  them,  some 
years  later,  abandoned  for  that  of  its  Devonian  age. 
These  eminent  geologists  did,  for  a  time,  put  forward  the 
view  (afterwards  relinquished)  that  the  gnel^^sic  series  of 
the  White  Mountains  consists  of  altered  Silurian  (Oneida- 
Clinton  strata),  and  Mather,  in  his  argument,  made  the 
most  of  the  error  of  H.  D.  Rogers,  who  mistook,  in  1840, 
certain  interstratified  crystalline  limestones  among  the 
Primary  gneisses  of  New  Jersey  for  superincumbent 
limestones  in  an  altered  condition;  but  Dana  fails  to  show 
that  the  Messrs.  Rogers  ever  maintained  the  paleozoic  age 
of  the  great  series  of  crystalline  rocks  in  southeastern 
New  York,  as  he  would  have  his  readers  infer.  When,  in 
1858,  H.  D.  Rogers  had  occasion,  in  his  final  report  on  the 
geology  of  Pennsylvania,  to  describe  the  continuation  of 
these  same  rocks  into  that  State,  he  distinctly  assigned 
them  to  a  horizon  below  the  base  of  his  paleozoic  series, 
proposing,  at  the  same  time,  a  Hypozoic  and  an  Azoic 
sj-stem  to  include  them. 

§  186.  The  Highland  range  en  the  east  side  of  the 
Hudson  traverses  Putman  County,  and,  passing  southwest- 


Y.  t^- 

strata,  Cam- 

iclusions  as 
en  adduced, 
3.  W.  B.  and 

learly  to   tLe 
assertion,  he 
1,  as  we  have 
30  under  the 
;hem  in  1841, 
,hical  Society. 
,n  Journal  of 
us  the  reader 
assertion  that 
if  1811,  maui- 
jonic  series, — 
L)f  them,  some 
Devonian   age. 
it  forward  the 
eissic  series  of 
urian  (Oneida- 
ent,  made  the 
Istook,  in  1840, 
es  among  the 
uperincumbent 

a,  fails  to  show 

le  paleozoic  age 

n  southeastern 

Ifer.     When,  in 

il  report  on  the 

jontinuation  of 

[inctly  assigned 

[aleozoic  series, 

and  an  Azoic 

ist  side  of  the 
tsing  southwest- 


XI.] 


THE  METAMOKPHIC   HYPOTHESIS. 


665 


ward  to  the  river,  occupies  but  a  small  area  in  the  north- 
west corner  of  Westchester  County.  Along  its  southeast 
base,  at  Annsville,  and  at  Oregon,  is  met  a  narrow  belt  of 
scarcely  crystalline  limestone,  accompanied  by  an  argillite 
or  talcoid  slate,  and  resting  unconformably  upon  the 
ancient  gneiss.  This  belt,  apparently  a  Lower  Taconic 
outlier,  is  regarded  by  Dana  as  partially  altered  Lower 
Silurian,  and  "the  grade  of  metamorphism  "  is  declared 
by  him  to  become  more  intense  to  the  south  and  east, 
giving  rise  to  the  whole  gueissic  area  of  Westchester  and 
New  York  Counties.  The  gneisses  and  conformably 
interstratified  crystalline  limestones  of  this  large  area  are, 
as  we  have  seen,  supposed  by  Dana  to  be  metamorphosed 
Lower  Silurian,  though  they  are  really  undistinguishable 
from  the  rocks  of  the  adjacent  Highland  range,  which  he 
admits  to  be  Archeun  or  Primary.  In  support  of  his 
startling  proposition,  Dana  might  be  expected  to  point 
out  some  distinctions  between  the  rocks  of  the  two  areas. 
He  begins  by  suggesting  certain  differences  as  to  more  or 
less  micaceous  or  hornblendic  gneisses  in  the  two  regions 
in  question,  but  confesses  that  "there  are  gradations 
between  tut  two,  in  both  respects,  which  make  the  appli- 
cation of  a  lithological  test  very  perplexing,"  *  and  admits 
that  "  the  lithological  evidence  of  diversity  of  age  is 
weak,"  a  criticism  which  is  equally  applicable  to  Dana's 
stratigraphical  argument. 

I  am  familiar  with  the  rocks  of  many  parts  of  West- 
chester County,  and  since  the  publication  of  Dana's  paper 
in  1880  have  taken  repeated  opportunities  to  examine 
the  rocks  called  by  him  Metamorphic  Lower  Silurian,  in 
various  localities,  as  at  Sing  Sing,  Tarrytown,  Yonkers, 
Spuyten  Duyvil,  and  Kingsbridge,  along  the  Hudson.  I 
have  also  studied  the  same  rocks  farther  to  the  east,  along 
the  River  Bronx  and  the  Harlem  Railroad,  to  Pleasant- 
vale,  as  well  as  between  this  line  and  the  Hudson,  and 
have  crossed  eastward  to  Long  Island  Sound,  and  examined 
*  Amer.  Jour.  Science,  1880,  xx.,  373. 


( 

(_i 

iiii 

II       ' 

wtk 

\ 

11 

w 

1! 

ti' . 

1         1 
'1        i 

i 

i. 

me 


THE  TACONIC   QUESTION  IN  GEOLOGY. 


[XI, 


(Vii 


i4ti 


1 1' 


the  exposures  on  the  shore  at  and  near  New  Roehelle. 
Being  already  familiar  with  the  Laurentian  rocks  through- 
out Canada,  as  well  as  in  parts  of  the  Adirondacks,  and  in 
the  Highlands  from  Putman  County,  New  York,  through 
New  Jersey  and  Pennsylvania  to  the  Schuykill,  and 
beyond,  I  do  not  hesitate  to  say  that  the  gneisses  and 
their  associated  crystalline  limestones  of  Dana's  so-called 
Metamorphic  Lower  Silurian,  in  Westchester  County, 
cannot  be  distinguished  from  the  typical  Laurentian.  I 
believe  that  tlie  judgment  of  an  impartial  observer  would 
be  that  the  notion  of  any  difference  between  the  Lauren- 
tian gneisses  and  limestones  of  the  areas  mentioned,  and 
the  gneisses  and  their  interstratified  limestones  of  West- 
chester County,  has  no  foundation  in  fiict. 

§  187.  Passing  now  from  Westchester  County  to  the 
adjacent  Manhattan  Island,  the  same  Laurentian  gneiss  is 
seen  in  its  northern  portion,  between  Seventh  and  Eighth 
Avenues,  especially  in  a  cutting  at  One  Hundred  and 
Fortv-fifth  Street,  and  thence  in  a  ridge  some  distance 
farther  south,  the  strata  being  nearly  vertical  and  of 
grayish  hornblendic  gnei&s,  and  a  band  of  crystalline  lime- 
stone appearing  a  little  farther  to  the  east,  on  Harlem 
River.  A  quarter  of  a  mile  to  the  west  of  tl  is  ridge,  in 
Mount  St.  Vincent,  is  seen  a  distinct  type  of  highly  mica- 
ceous gneiss,  and  mica-schists,  and  similar  rocks  are 
exposed  at  intervals  in  the  western  part  of  the  island,  as 
far  south  as  Fifty-ninth  Street.  Farther  eastward,  in  tiie 
southern  part  of  Central  Park,  just  above  Fifty-ninth 
Street,  the  numerous  rock-exposures  are  all  of  similar 
mica-schists,  and  micaceous  gneisses,  often  at  moderate 
angles.  They  include  endogenous  granitic  veins,  occa- 
sionally presenting  in  their  structure  a  marked  bilateral 
symmetry,  ond  sometimes  tranverse,  but  at  other  times 
interbedded.  Several  perched  blocks  here  found  are  of 
similar  endo-renous  granite,  and  are  apparently  boulders 
of  decomposition,  left  in  the  sub-aerial  decay  of  the  rocks 
of  the  region.     These  micaceous  rocks  are  unlike  those  of 


Y. 


[XI 


XI.] 


THE   METAMORPHIC   HYPOTHESIS. 


667 


\v  Rochelle. 
;ks  througli- 
acks,  and  in 
jrk,  through 
luykill,   autl 
Tueisses  and 
Ill's  so-called 
ter    County, 
lurentian.     I 
server  woukl 
the  Lauren- 
jiitioned,  and 
nes  of  West- 

lounty  to  the 
itian  gneiss  is 
h  and  Eighth 
Hundred  and 
some  distance 
rtical  and  of 
ystalline  lime- 
,t,  on  Harlem 
tV.is  ridge,  in 
f  highly  mica- 
ar  rocks    are 
the  island,  as 
Isi-ward,  in  the 
re    Fifty-ninth 
[all   of  similar 
li  at  moderate 
[c  veins,  occa- 
irked  bilateral 
tt  other  times 
found  are  of 
[ently  boulders 
ly  of  the  rocks 
inlike  those  of 


Laurentian  areas,  but,  on  the  contrary,  closely  resemble 
those  of  the  White  Mountains,  and  of  Pliiladelphia,  which 
I  have  called  Montaibau,  and  are  like  tlie  younger  gneissic 
series  of  the  Alps  and  the  Scottisli  Highlands.  I  there- 
fore, as  long  ago  as  1871,  *  noticed  these  rocks  as  belong- 
ing to  this  younger  series,  and  have  since  expressed  the 
opinion  that  the  Laurentian  "of  Manhattan  Island  appears 
to  be  overlaid  in  parts  by  areas  of  younger  gneisses  and 
mica-scl lists,  the  remaining  portions  of  a  mantle  of  Mont- 
alban."  f  It  is,  however,  by  an  error  for  which  I  am  not 
responsible,  that  in  James  Macfarlane's  "  Geological  Rail- 
road Guide,"  in  1878,  the  Montaibau  of  Manhattan  Island 
has  been  represented  as  extending  upward  along  the 
Hudson  River  Railroad  by  Spuyten  Duyvil,  Yonkers, 
Tarrytown,  and  Sing  Sing,  as  far  as  Croton,  before  meet- 
ing the  Laurentian  of  the  Highlands.  There  appears, 
nevertheless,  to  be  an  outlier  of  Montalban  rocks  at 
Cruger's  Station,  just  above  Croton,  and  there  may  be 
others  in  various  parts  of  Westcliester  County. 

§  188.  It  has  been  deemed  necessary  to  notice  thus  at 
length,  in  this  coiniection,  Dana's  resuscitation  of  the 
ancient  views  of  Mather,  for  two  reasons :  first,  because 
therein,  both  the  Lower  Taconic  rocks  and  various  crys- 
talline rocks  just  noticed,  are  supposed  by  him  to  be  con- 
tiguous portions  of  the  same  Cambrian  and  Ordovician 
(Lower  Silurian)  sediments  in  different  stages  of  trans- 
formation ;  and  secondly,  because  the  manner  in  wliich 
the  names  of  the  brothers  Rogers  are  cited  by  Dana 
in  conjunction  with  that  of  Mather  is  such  as  to  lead 
the  reader  to  the  false  conclusion  that  those  eminent 
geologists  supported  Mather's  hypothesis  of  1843  as 
to  the  Cambrian  and  Ordovician  age  of  these  same  crys- 
talline rocks,  as  well  as  that  of  the  Lower  Taconic 
series ;   which   latter   view,   as  we    have  shown,  W.  B. 

*  Hunt.    President's  Address  before  the  Amer.  Assoc.  Adv.  Science, 
1871;  in  Cliem.  and  Geol.  Essays,  pp.  24S  and  197. 
t  Smithsonian  lieport  for  187S,  Progress  of  Geology. 


!}!»-* 


668 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


Rogers  repudiated  a  few  years  afterwards,  in  1851,  and 
again  in  1860. 

§  189.  The  rise  and  fall  of  the  doctrine  of  regional 
metaniorphism,  which  is  but  an  extravagant  development 
of  the  Huttonian  hypothesis  of  the  origin  of  crystalline 
rocks,  forms  a  curious  chapter  in  the  history  of  geology. 
I  have  elsewhere  related  the  early  application  of  this 
doctrine  to  the  crystalline  rocks  of  Mont  Blanc  by  Ber- 
trand,  about  1797,  and  its  subsequent  restatement  by  Kef- 
erstein  in  1834,  until  it  was  taken  up  and  popularized  by 
Lyell,  Murchison,  and  various  continental  geologists,  so 
that  the  view  became  generally  accepted  that  the  gneisses 
and  mica-schists  of  the  Alps  an-  but  altered  secondary 
and  tertiary  strata.  The  story  of  the  refutation  of  this 
hypothesis  for  the  Alps  by  the  studies  of  Favre,  Pillet, 
Gastaldi,  and  others,  has  also  been  told.*  A  similar 
view  was  extended  to  crystalline  rocks  in  other  parts  of 
continental  Europe,  in  the  British  Islands,  and  in  eastern 
North  America,  save  that  to  all  of  these  a  paleozoic  age 
was  generally  assigned.  The  opinions  of  Mather  on  this 
subject  were  adopted  by  Logan  and  others,  including  the 
present  writer.  Tlie  brothers  Rogers,  in  1846,  advanced 
a  similar  view  for  the  rocks  of  the  White  Mountains,  but 
abandoned  it  before  1858.  It  was  not  until  1870  and 
1871  that  the  present  writer,  rejecting  entirely  the  views 
of  this  school,  asserted  the  pre-Cambrian  age  of  all  the 
great  areas  of  crystalline  rocks,  alike  in  North  America 
and  in  Europe.  Nearly  coinciding  in  time  with  this,  came 
the  independent  action  of  numerous  continental  geolo- 
gists, including  those  already  named,  and  the  result  has 
been  such  an  advance  of  the  views  of  the  new  school  that, 
in  1881,  Callaway  could  say  that  "  every  case  of  supposed 
metamorphic  Cambrian  and  Silurian  has  been  invalidated 
by  recent  researches,"  and  in  1883  Bonney  wrote  that 
the  hitherto  accredited  "instances  of  metamorphism   in 

*  Amer.  Jour.  Science,  1872,  iii.,  9,  and  Chem.  and  Geol.  Essays,  pp. 
338-342  and  347,  348.    Also,  ante,  Essay  X.,  part  iv.       . .   ,,  .  ,,   . , 


XI.] 


THE  METAMOllPHIC   HYPOTHESIS. 


669 


Geol.  Essays,  pp. 


Wales,  and  especially  in  Anglesey,  in  Cornwall,  in  Leices- 
tershire, and  in  Worcestershire,  have  utterly  broken  down 
on  careful  study;"  *  as  had  already  been  the  case  in  the 
Alps  and  in  North  America. 

§  190.  The  last  stronghold  of  the  metamorphic  school 
in  the  British  Islands  was  in  the  northwest  of  Scotland, 
where  Cambrian  and  Ordcnician  fossiliferous  sandstones, 
limestones,  and  shales,  resting  upon  the  ancient  granitoid 
gneisses  to  the  west,  are,  towards  the  east,  overlaid,  in 
apparent  conformity,  by  a  great  series  of  unlike  gneisses 
and  mica-schists,  which  form  the  Scottish  Highuinds,  and 
were  declared  by  Murchison  and  Archibald  Geikie,  from 
their  studies,  to  consist  of  still  newer  rocks  in  a  so-called 
metamorphic  condition.  The  structure  of  this  north- 
western part  of  Scotland  was,  in  fact,  according  to  their 
teaching,  the  procise  counterpart  of  that  of  New  England, 
as  formerly  taught  by  Mather  and  his  followers,  and  still 
supported  by  Dana.  The  late  Professor  Nicol,  however, 
constantly  opposed  this  view  of  the  structure  of  the 
Highlands  maintained  by  Murchison  and  by  Geikie,  while 
the  present  writer,  from  his  lithological  studies  of  the 
Highland  rocks,  declared  in  1871  his  conviction  that  the 
upper  gneisses  of  "  the  Scottish  Highlands  will  be  found 
...  to  belong  to  a  period  anterior  to  the  deposition  of 
the  Cambrian  sediments,  and  will  correspond  with  the 
newer  gneissic  series  of  our  Appalachian  region,"  f  then 
descri- "ed  as  the  White  Mountain  series,  —  an  opinion 
which  was  reiterated,  after  farther  examination  of  speci- 
mens of  the  rocks,  'ia  a  communication  in  1881  to  the 
Geological  Society  of  London,  when  these  Highland  gneis- 
ses were  designated  as  Montalban.J 

§  191.  The  studies  by  Hicks  of  the  geology  of  parts 
of  this  region,  from  1878,  and  the  later  and  independent 

*  Callaway,  Geological  Magazine,  Sept.  1881,  p.  423,  and  Bonney,  ibid., 
Nov.,  1883,  p.  507. 

t  Hunt,  President's  Address  before  the  Amer.  Assoc.  Adv.  Science, 
1871,  and  Chem.  and  Geol.  Essays,  p.  272. 

}  Froc.  Geol.  Soc.  London,  in  Geological  Magazine,  1882,  ix.,  39. 


\r. 


,i! 


I  I 


670 


THE  TACONIC  QUESTION   IN  GEOLOGY. 


[XT. 


I 


t; 


*fcb 


f 


^1 


ones  of  Callaway  and  of  Lapworth  in  other  districts,  had 
already,  in  the  beginning  of  1883,*  shown  the  fallacy  of 
the  views  maintained  by  Murchison  and  Geikie  as  to  the 
geological  structure  of  the  Highlands.  The  united  testi- 
mony of  these  observers  made  it  clear  that  in  the  region 
in  question  were  portions  of  two  gneissic  series, —  an  older 
or  granitoid  gneiss,  like  that  of  the  western  coast,  and  a 
younger,  very  distinct  in  type,  which  has  been  variously 
designated  as  Upper  Pebidian,  Grampian,  and  Caledonian, 
and  is  that  described  by  me  in  1871,  and  again  in  1881,  as 
of  the  White  Mountain  or  Montalban  type.  This,  the 
younger  gneissic  series  of  Murchison  and  Geikie,  was 
clearly  established  to  be  of  great  thickness,  and  older 
than  the  fossiliferous  Cambrian,  which  it  is  brought  to 
overlie  by  a  series  of  great  folds,  overturned  to  the  west, 
and  accompanied  by  parallel  faults,  with  upthrows  on  the 
east  side,  as  shown  by  Hicks  in  Ross  and  Inverness  shires, 
as  well  as  by  Callaway  in  Assynt,  and  by  Lapworth  in 
Eriboll  (ante.,  p.  423). 

§  192.  The  concordant  and  independent  results  of  the 
eminent  observers  just  named  having  thus  demonstrated 
the  fallacy  of  the  view  of  Murchison  and  Geikie  that  the 
gneiss,  which  in  the  Highlands  overlies  the  fossiliferous 
strata,  is  a  still  younger  paleozoic  series  in  an  ?ltered  con- 
dition, the  geological  survey  of  Great  Britain,  of  which 
Geikie  is  now  director,  undertook,  in  1883  and  1884,  a  re- 
examination of  the  region  in  question.  The  result  of  this 
has  completely  disproved  the  former  statements  of  Mur- 
chison and  Geikie,  and  has  confirmed  those  of  the  new 
school.     Geikie,  in  a  note  recently  published,!  tells  us 

*  Hicks,  Qiwr.  Geol.  Jour.,  1878,  xxxiv.,  816;  Geol.  Mag.,  1880,  vi.; 
also  Quar.  Geol.  Jour.,  1883  (with  appended  notes  by  Bonuey),  in  ab- 
stract in  Geol.  Mag.,  Marcli,  188o,  x.,  p.  137.  Callaway,  ibid.,  x.,  pp. 
139  and  330;  and  Lapworth,  ibid.,  x.,  pp.  120,  192,  337;  also  Callaway  on 
Progressive  Metamorphism,  ibid.,  May,  1884;  and  summaries  in  accounts 
of  the  Progress  of  Geology  in  the  Reports  of  the  SiuitUsouiau  Instituticu 
for  1882  and  1883. 

t  Nature,  Nov.  13,  1884,  xxxi.,  22-35. 


.OGY. 


[XI. 


r  districts,  had 
the  fallacy  of 
eikie  as  to  the 
he  united  testi- 
;  in  the  region 
jries, — an  older 
rn  coast,  and  a 
been  variously 
md  Caledonian, 
gain  in  1881,  as 
^pe.      This,  the 
id   Geikie,  was 
iiess,  and  older 
t  is  brought  to 
led  to  the  west, 
.ipthrows  on  the 
[nverness  shires, 
by  Lapworth  in 

it  results  of  the 
18  demonstrated 
Geikie  that  the 
the  fossiliferous 
an  plteredcon- 
ritain,  of  which 
and  1884,  a  re- 
le  result  of  this 
ements  of  Mur- 
lose  of  the  rew 
ished,t  tells  us 

eol.  Mag.,  1880,  vi.; 
by  Bonney),  in  ab- 
ilaway,  ibid.,  x.,  pp. 
n ;  also  Callaway  on 
mmaries  In  accounts 
tbsoniau  Institution 


XI.] 


THE  METAMOUPHIC   IlYl'OTIIESIS. 


G71 


that  he  has  "found  the  evidence  altogether  overwhelming 
against  the  upward  succession,  which  Murchison  believed 
to  exist  in  Eriboll,  from  the  base  of  the  Silurian  strata  in- 
to an  upper  conformable  series  of  schists  and  gneisses," 
and  adds:  "Tliat  there  is  no  longer  any  evidence  of  a 
regular  conformable  passage  from  fossiliferous  Silurian 
quartzites,  shales,  and  limestones,  upwards  into  crystiilline 
schists,  v/hich  were  supposed  to  be  metamorphosed  Silu- 
rian sediments,  must  be  frankly  admitted."  The  same 
conclusions  are  also  reached  by  Geikie  from  the  re-exami- 
nation of  the  similar  sections  in  Ross-shire,  previously 
described  by  himself  in  accordance  with  the  views  of 
Murchison.  The  preliminary  rei)ort  of  the  surveyors, 
Messrs.  Peach  and  Home,  which  is  subjoined  to  the 
director's  note,  shows  the  same  structure  as  was  already 
described  by  the  late  ob-servers,  namely,  overturned  folds 
and  great  faults,  with  lateral  thrusts  westward,  by  which 
the  gneisses  are  made  to  overlie  the  fossiliferous  strata, — 
the  horizontal  displacement  of  the  gneisses  to  the  west, 
which  are  superimposed  on  the  Cambrian  rocks,  being,  in 
some  cases,  according  to  Geikie,  not  less  than  ten  miles. 

[Judd,  who,  in  1885,  reviewed  before  the  British  Asso- 
ciation the  early  work  of  NicoU  in  this  region,  writes  that 
in  a  paper  by  the  latter,  published  by  the  Journal  of  the 
Geological  Society  in  1861,  he  "must  be  admitted  to  have 
established  the  main  facts  concerning  the  geology  of  tiie 
Highlands  as  accepted  by  all  geologists  at  the  present 
day."  He  adds  that  the  conclusions  arrived  at  by  Nicoll 
in  early  as  1860,  those  of  the  later  investigations  named, 
previous  to  1883,  and  those  of  the  British  geological 
survey  in  1883  and  1884,  "are  in  all  their  main  features 
absolutely  identical,  and  the  Murchison ian  theory  of  the 
Highland  succession  is  now,  by  universal  consent,  aban- 
doned.*] 

§  193.  Geikie  notices  the  distinction  between  the  older 
or  granitoid  gneiss,  portions  of  which  also  appear  in  the 

.1  :  *  Nature,  xxxii.,  455,  45G. 


I 


i 


m  '■ 


.1'; 


672 


THE  TACONIO  QUESTION   IN  GEOLOGY. 


[xr. 


i 

9  M 

f  ! 

fe 

^9  '!.. 

II 

JTT IJH  HflPPHPIIIIH 

[9^B  ' 

i'  1 

'"'>'9| ' 

%M 

'^4 

' ' ' ' 

Highlands,  and  the  upper  gneissic  and  mica-schist  series, 
the  pre-paleozoic  age  of  which  was  sliown  by  the  observa- 
tions alike  of  Hicks,  of  Callaway,  and  of  Lapworth.  He 
calls  attention  to  the  laminated  and  schistose  structure 
developed  by  the  great  pressure  and  friction  along  the 
lines  of  movement  in  gneissic  and  hciiblendic  rocks,  and 
also  to  similar  changes  produced  by  the  same  agency  in 
detrital  rocks,  such  as  arkose.  Both  of  these  structural 
alterations  are  apparently  included  by  Gcikio  under  the 
head  of  what  he  calls  a  "regional  metamorphism,"  —  a 
misapplication  of  the  term  likely  to  confuse  the  reader, 
since  local  structural  changes,  induced  by  mechanical 
movements  in  ancient  crystalline  rocks,  have  nothing  in 
common  with  that  mysterious  process  which  has  been 
supposed  by  the  metamorphic  school  to  generate  similar 
crystalline  rocks  from  uncrystalline  sediments.  As  re- 
gards the  changes  wrought  by  the  same  agency  on  detrital 
masses,  it  may  be  repeated  that  "the  resemblance  between 
primitive  crystalline  rocks  and  what  we  know  to  be  detri- 
tal rocks  compressed,  recemented,  and  often  exhibiting 
interstitial  minerals  of  secondary  origin,  is  too  slight  and 
snperficial  to  deceive  the  critical  student  in  lithology,  and 
disappears  under  microscopical  investigation"  (^ante,  p. 
108.) 

§  194.  We  have  already  elsewhere  in  this  essay  (§  135) 
referred  to  the  local  development  of  crystalline  silicates  in 
sedimentary  rocks  by  infiltration,  and  have  in  another 
place  considered  the  relation  of  such  a  process  to  the 
question  of  the  origin  of  Primitive  crystalline  rocks. 
These  we  believe  to  have  been  formed  anterior  to  the 
existence  of  detrital  sediments,  and  by  a  process  which 
excludes  alike  all  so-called  metamorphic,  metasomatic, 
and  plutonic  hypotheses  of  their  origin.  At  the  same 
time,  we  reject  the  Wernerian  or  chaotic  hypothesis;  and 
its  modification  by  De  la  Beche  and  Daubr^e,  which  we 
have  called  thermochaotic,  in  favor  of  a  new  aqueous  or 
neptunian  hypothesis,  which  supposes  the  elements  of 


Y. 


XL] 


THE  TACONIC   SERIES. 


G73 


chist  series, 
the  observa- 
(WortU.    He 
vjo  structure 
u  along  the 
c  rocks,  and 
le  agency  in 
se  structural, 
ie  under  the 
rphism,"  — a 
e  the  reader, 
f  mechanical 
e  nothing  in 
leh  has  been 
lerate  similar 
3nts.      As  re- 
icy  on  detrital 
lance  between 
)\v  to  be  detri- 
,en  exhibiting 
;oo  slight  and 
lithology,  and 
on"   (ante,  p. 

essay  (§  135) 
^ne  silicates  in 
\iQ  in  another 
Lrocess  to  the 
ktallin.e   rocks, 
literior  to  the 
{process  which 
metasoniatic, 
At  the  same 
lypothesis;  and 
|v6e,  which  we 
Iw  aqueous  or 
elements  of 


tlicse  rocks  to  Imve  been  dissolved,  and  bronc;ht  to  tlu' 
surface  IVdiii  a  disintofifiuted  layer  of  Ij^mu'ous  basic  rock, 
the  sn[H'rtiL'ial  and  last-solidiliud  poilioii  of  u  cooHmlj 
globe,  through  tlu*  action  of  circulating  waters.  The 
soluble  and  insoluhle  products  of  the  sub-uerial  decay 
alike  of  igneous  and  aqueous  rocks  are,  however,  con- 
ceived to  have  intervened  in  the  process,  especially  during 
the  period  of  the  later  crystalline  or  Transition  rocks. 
This  exi)lanation  of  their  genesis,  which  we  have  called 
the  crenitic  hypothesis,  is  discussed  at  length  in  Essay  \. 
of  the  present  vohuue. 

IX.  —  CONCLUSIONS. 

§  195.  The  task  attempted  in  the  preceding  chapters, 
of  discussing  the  history  of  the  Taconic  question,  has 
involved  a  review  of  much  of  the  work  done  in  American 
geology  for  more  than  sixty  years,  going  back  to  the 
labors  of  Eaton,  and  even  to  those  of  Maclure.  Of  tiie 
somewhat  extensive  literature  *  of  the  subject  I  have 
made  use,  so  far  as  has  seemed  of  importance,  in  the  con- 
troversies whicli  have  arisen  on  this  question,  and  have 
supplemented  the  researches  of  various  investigators  by 
personal  observations  extending  over  a  wider  field  and  a 
greater  number  of  years  than  those  of  any  of  my  prede- 
cessors. From  all  of  tliese  sources,  I  have  here  sought  to 
bring  togetlier  whatever  has  appeared  to  be  of  value  for 
the  elucidation  of  the  important  problems  before  us.  In 
the  following  sections,  the  conclusions  which  have  already 
been  set  forth  at  length  are  summed  up. 

§  196.  There  exists  in  eastern  North  America  a  great 
group  of  stratified  rocks,  consisting  of  quartzites,  lime- 

*  Dana,  in  the  Amer.  Jour.  Science  for  1880,  xix.,  163,  has  given  "a 
list  of  tlie  principal  papers"  on  the  Taconic  System,  in  wliich,  wliile  pro- 
fessing to  bring  togetlier  those  adverse  to  the  pre-Cainbrian  age  of  the 
Taconiau,  he  omits  all  reference  to  the  opinions  of  Ailams,  of  Kd.  Ilitch- 
coclc,  and  the  later  conclusions  of  \\.  B.  Rogers  as  lo  tlie  (Upper)  Silu- 
rian or  Devonian  age  of  the  Taconian  limestones.  'J'he  list  is  in  other 
respects  very  incomplete,  and  serves  to  mislead  the  student. 


074 


THE  TACONIC  QUESTION  IN  GEOLOGY, 


rcr. 


(    ' 


it   ^ 


stones,  argillites,  and  soft  crystalline  schists,  which  hiivo 
together  a  thickne.ss  of  4000  feet  or  more,  and  are  found 
resting  unconforniably  ui)()n  various  niore  ancient  crystal- 
line rocks,  from  tlie  Laurentian  to  the  Montalban  inclu- 
sive. This  series,  called  Transition  by  Maclure,  includes 
the  Primitive  Quartz-rock,  the  Primitive  Lime-rock,  and 
the  Transition  Argillite  of  Eaton,  and  is  the  Lower 
Taconic  of  Emmons,  and  the  Itacolumitic  group  of 
Lieber.  The  series,  which  I  have  preferred  to  cull  Taco- 
nian,  is  essentially  one  of  Transition  crystalline  rocks. 
The  (juartzites,  which  predominate  in  the  lower  portion, 
contain  much  detrital  matter,  and  are  sometimes  conglom- 
erates. They  are,  however,  often  vitreous  or  granular,  the 
latter  variety  being  sometimes  flexible  and  clastic,  and 
constituting  what  is  called  elastic  sandstone  or  itacolu- 
mite.  These  quartzites,  like  the  limestones  of  the  series, 
often  contain  an  indigenous  micaceous  substance,  which 
is  in  most  cases  a  hydrous  muscovitic  mica,  related  to 
sericite  or  to  damourite.  A  similar  mineral  predominates 
in  certain  layers  of  soft  unctuous  lustrous  schists,  which, 
from  their  aspect,  have  been  called  talcoid  or  magnesian, 
and  are  found  intercalated  alike  v  ^^^  the  quartzites  and 
the  limestones  of  the  series.  TliC  latter,  often  more  or 
less  magnesian,  are  generally  finely  granular,  and  yield 
marbles  for  statuary  and  for  architecture.  They  are  often 
variegated  in  color  or  banded  with  green  or  gray,  consti- 
tuting cipolins.  The  mineralogy  of  the  limestones  and 
their  associated  crystalline  schists  has  been  noticed  in 
§§  51,  65,  68,  76-79,  and  farther,  on  page  184  of  the 
present  volume,  and  it  has  been  shown  that  the  Taconian 
is  an  important  ore-bearing  horizon,  including,  besides 
great  deposits  of  magnetite,  and  of  hematite,  others  of 
siderite  and  of  pyrite.  Both  of  the  latter  species,  by  epi- 
genesis,  give  rise  to  hydrous  iron  ores,  which,  throughout 
the  Appalachian  region,  characterize  the  outcrops  of  the 
series,  and  are  generally  imbedded  in  clays,  the  result  of 
the  sub-aerial  decay  of  the  enclosing  schists,  which,  it  may 


OY.  P*'' 

3,  which  \iivve 
lul  are  found 
icient  crystal- 
iitalbivn  iiiclu- 
eluve,  indudes 
/ime-rock,  ami 
is  tho   Lower 
itic    gioup    of 
d  to  call  Taco- 
^•stallino  rocks, 
lower  portion, 
itimes  congh)ni- 
ov  granular,  tho 
lud  elastic,  and 
tone  or  itacolu- 
les  of  the  series, 
,ubstance,  which 
mica,  related  to 
-al  predominates 
9  schists,  which, 
d  or  magnesian, 
3  quartzites  and 
r,  often  more  or 
uular,  and  yield 
They  are  often 
or  gray,  consti- 
limestones  and 
been  noticed  in 
5age  1B4  of   the 
at  the  Taconiau 
.eluding,  besides 
matite,  others  of 
sv  species,  by  epi- 
■hich,  throughout 
outcrops  of  the 
xys,  the  result  of 
Lsts,  which,  it  may 


XI.J 


TllK  TACONIC   SERIES. 


fi76 


theuco  1)0  conjectured,  inchido,  in  nuiny  cases,  huge  pro- 
portions of  a  ields|)iitl,ic  mineral.  The  argillites  of  the 
Tai!onian,  often  yichliug  rooluig-shiteH,  are  intcrstratiru'd 
with  more!  or  less  silicious  beiU,  and  o(!cur  chielly  in  tlie 
upl)er  part  of  the  series. 

§  11)7.  These  Taconian  rocks  are  not  confined  to  the 
Appahichian  vall(;y.  Extending  southward  therefrom, 
tliey  are  traced  in  Pennsylvania  ah)ng  the  eastern  base  of 
tho  lilue  Kidge  into  North  Carolina,  and  are  found  in 
outliers  to  the  east,  over  the  Atlantic  belt  from  (Jeorgia 
to  New  Brunswick  and  Nova  Si'otia.  To  the  west  of  tlie 
great  valle}',  tliey  are  known  to  underlie  the  eastern  part 
of  the  paleozoic  basin,  and  appear  in  eroded  anticlinals 
from  beneath  tiie  coal-measures,  alike  in  Alabama  and 
Pennsylvania,  where  they  are  overlai<l  b}'  Ordoviciau 
strata.  They  are  seen  in  similar  conditions,  lying  nncon- 
formably  beneath  the  Ordoviciau  limestones  of  the  Ottawa 
baain,  in  Hastings  County,  Ontario,  and  are  represented 
by  the  great  series  of  quartzites,  limestones,  argillites, 
and  crystalline  schists,  with  iron-ores,  around  Lake  Supe- 
rior, which,  as  wo  have  endeavored  to  show  on  pages 
679  and  581,  have  been  generally  confounded  with  the 
Huronian,  but  were  designated  by  the  writer  in  1873  as 
the  Animikio  series,  and  had  long  before  been  by  Hough- 
ton and  Emmons  referred  to  the  Taconiau  system.  This, 
according  to  information  got  from  Houghton,  was  declared 
by  Ennuons  in  1F46  to  be  largely  develoi)ed  in  the  cen- 
tral and  western  parts  of  the  upper  peninsula  of  Michigan, 
the  slates  being  well  ex})osed  on  the  line  of  the  Menomi- 
nee River;  while  farther  east,  near  to  Lake  Superior,  the 
Granular  Quartz-rock  was  said  to  appear,  with  a  northe-^st 
strike,  in  hills  several  hundred  feet  high.  In  1855,  it  was 
farther  stated  by  Emmons  that  collections  of  the  rocks 
from  this  region  presented  all  the  lithological  characters 
of  those    from    eastern   New  York.*     They  were,  more- 

*  Aprlculture  of  New  York,  i.,  p.  101;  American  Geology,  ii.,  p.  118, 
and  Manual  of  Geology,  p.  80. 


676 


THE  TACONIC  QUESTIOIn"  IN  GEOLOGY. 


pci. 


V  I 


r  -t^ 


over,  found  by  Houghton  to  be  overlaid  by  the  Potsdam 
sandstone,  and,  as  we  now  know,  are  also  inferior  to  the 
Keweenian.  Taconic  rocks,  we  were  subsequently  told 
by  Emmons,  occur  "in  Arkansas,  in  the  vichiity  of  the 
Hot  Springs."  *  The  argillites  and  quartzites  which  in  the 
Black  Hills  of  Dakota  intervene  between  the  lower  crys- 
talline rocks  and  the  Cambrian,  resemble  those  of  the 
Taconian,  and  the  same  must  be  said  of  the  quartzites 
with  argillites,  lustrous  schists,  and  crystalline  limestones, 
which  ^ho  writer  has  noticed  in  a  similar  position  in  the 
Tintic  Hills  in  Utah. 

§  198.  The  Taconian  series  is  not  destitute  of  evi- 
dences of  organic  life,  but  contains,  in  the  granular 
quartzites  near  its  base,  the  typical  Seolithus  linearis  at 
many  points  throughout  the  Appalachian  valley.  Similar 
markings  in  the  silicious  beds  of  the  series  in  Hastings 
County,  Ontario,  have  been  noticed  as  probably  worm- 
burrows  by  J.  W.  Dawson,  who  has  also  described  the 
Eozoon  Canadense  found  in  the  associated  limestones, 
while  the  argillites  which  I  have  referred  to  this  series, 
from  the  western  end  of  Lake  Superior,  have  afforded 
the  remains  of  a  sponge.  The  Taconian,  as  I  have  sug- 
gested, may  constitute  a  link  between  the  older  eozoic 
groups  and  those  of  paleozoic  time. 

§  199.  The  Upper  Taconic,  which  is  the  First  Gray- 
wacke  and  the  Sparry  Lime-rock  of  Eaton,  and  the 
Potsdam  and  Quebec  groups  of  Logan  (including  a 
large  part  of  what  was  described  by  Mather,  and  by 
Logan  previous  to  1861,  as  Hudson-River  group),  we 
have  seen  to  be  the  Appalachian  representative  of  the 
Cambrian  period.  It  sometimes  overlies  the  Taconian, 
but,  in  the  absence  of  this,  rests  directly  upon  the  older 
crystalline  groups  along  the  eastern  border  of  the  great 
Appalachian  basin.  Unlike  the  Taconian,  however,  it 
does  not,  so  far  as  known,  extend  eastward  of  this 
limit,  while  to  the  west,  as  v/e  recede  from  this  border, 
*  Manual  of  Geology,  p.  89. 


i  i: 


XI.] 


GY.  ■      I*** 

r  the  Potsdam 
nferior  to  the 
lequeiitly  told 
icinity  of  the 
}s  which  in  the 
lie  lower  crys- 
3  those  of  the 
the  quavtzites 
Line  limestones, 
position  in  the 

jstitute   of  evi- 
1  the    granular 
'thus  linearis  at 
valley.     Similar 
ries  in  Hastings 
probably  worm- 
lo  described  the 
,\ted   limestones, 
a  to  this  series, 
have  afforded 
as  I  have  sug- 
he  older  eozoic 

tlie  First  Gray- 
Eaton,   and   the 
an    (including   a 
Mather,  and  by 
Aver  group),  we 
-sentati\e  of  the 
2S  the  Taconian, 
y  upon  the  older 
der  of  the  great 
ian,  however,   it 
;astward   of    this 
i-oni  this  border, 


THE  TACONIC   SERIES. 


G77 


it  is  soon  replaced  by  the  Adirondack  type  of  the  Cam- 
brian. 

This  Appalachian  Cambrian  series  is  wholly  un crystal- 
line, and  is  separated  from  the  Taconian  by  a  stratigraphi- 
cal  break,  and  by  a  great  interval  of  time,  which  includes 
the  Keweenian  period.  From  the  distribution  of  the 
Cambrian  and  the  Ordovician  in  eastern  North  America, 
there  was  evidently  another  great  stratigraphical  break, 
with  erosion  (followed  by  a  considerable  continental  de- 
pression), which  preceded  the  deposition  of  the  Ordovician 
limestones.  Similar  disturbances  seem  to  have  inter- 
vened at  the  beginning  of  the  Silurian  period,  in  this  east- 
ern region,  for  we  find  the  Silurian  limestones  resting 
directly  upon  somewhat  inclined  and  eroded  Ordovician 
strata  near  Montreal,  and  apparently,  also,  in  the  valley 
of  the  Hudson,  while  throughout  this  eastern  border  the 
great  mechanical  sediments  of  the  Oneida,  Medina,  and 
Clinton,  which  to  the  west  of  the  River  Hudson  con- 
stitute  the  chief  part  of  the  Second  Gray  wacke  of  Eaton, 
at  the  base  of  these  limestones,  are  apparently  absent, — a 
fact  pointing  to  the  emergence  of  this  eastei'n  region 
during  the  early  part  of  Silurian  time.  The  local  disturb- 
ances which  at  this  period  prevailed  in  the  eastern  part  of 
the  great  basin  are  farther  shown  in  the  conglomerate 
character  of  these  Silurian  sandstones  in  parts  of  New- 
York  and  Pennsylv  ania,  though  it  should  be  noted  that  in 
these  regions,  as  well  as  in  Ontario,  there  appears  to  be 
an  unbroken  succession  from  the  Loraine  shales  to  the 
Oneida,  Medina,  and  Clinton  subdivisions. 

§  200.  As  a  result  of  all  these  various  movements 
which  affected  the  eastern  border  of  the  Appalachian 
basin,  we  find  that  the  Taconian  is  there  in  some  parts 
directly  overhiid  by  Cambrian,  in  others  by  Ordovician 
strata,  and  in  parts,  it  would  seem,  by  limestones  belong- 
ing to  the  upper  portion  of  the  Silurian,  or  to  Devonian 
time.  The  strata  of  all  of  these  periods  are  more  or  less 
involved  with  each  other,  and  with  still  older  crystalline 


678 


THE  TACONIC   QUESTION  IN  GEOLOGY. 


[XI. 


4? 


§m 


i;;»* 


groups,  by  the  successive  movements  of  folding  and  dis- 
location which  continued  to  affect  the  Atlantic  belt,  at 
intervals,  until  after  the  close  of  paleozoic  time.  From 
the  complex  stratigraphical  relations  which  have  thus 
resulted,  various  observers  have,  during  the  past  forty 
years,  conjectured  that  the  Taconian  limestones  are  strata 
of  Cambrian,  of  Ordovician,  of  Silurian,  or  even  of  Devo- 
nian age,  which,  by  a  process  of  so-called  metamorphism, 
have  been  changed  into  granular  non-fossiliferous  marbles, 
often  holding  crystalline  silicates. 

§  201.  These  various  conjectures  are  not  only  in  con- 
tradiction with  each  otlier,  but,  as  we  have  seen,  are  in 
direct  conflict  with  the  facts  of  stratigraphy,  and  are, 
moreover,  based  upon  the  unproved  and  now  generally 
discredited  hypothesis  of  progressive  and  regional  meta- 
morphism. This  hypothesis,  as  long  since  maintained  by 
Mather  for  the  rocks  of  eastern  North  America,  and  later 
by  Dana,  asserts  successive  changes,  —  called  by  the  latter 
"grades  in  metamorphism," — from  uncrystalline  sediments, 
through  the  Taconian  and  other  more  massive  crystalline 
schists,  to  the  granitoid  gneisses.  These  various  and  dis- 
similar groups  of  strata,  as  I  maintained  in  1878,  and  as  will 
to-day  be  admitted  by  nearly  all  geologists,  "are  not  the 
result  of  different  and  unlike  changes  which  one  and  the 
same  uncrystalline  paleozoic  series  has  suffered  in  different 
geographical  areas,  but,  on  the  contrary,  belong  to  success- 
ive periods  in  paleozoic  and  eozoic  time.  The  great  divis- 
ions of  the  latter  .  .  .  present  in  asnending  order  a 
progressive  change  in  mineral  character,  the  nature  of 
which  has  been  shown ;  .  .  .  thus  constituting  a  veritable 
passage  in  time  from  the  granitoid  Ottawa  gneiss  at  the 
base  of  the  Laurentian,  through  the  intermediate  Iluroii- 
ian  and  Montalban  divisions,  to  the  less  markedly  crystal- 
line schists  of  the  Taconian."*  Such  a  succession,  I  have 
since  endeavored  to  show,  is  the  necessary  result  of  the 
secular  process  by  which,  from  an  undifferentiated  primeval 
*  Hunt,  Azoic  Rocks,  1878,  p.  253;  see  also  ibid.,  p.  210. 


XL] 


THE  TACONIC   SERIES. 


670 


chaos,  the  various  groups  of  Primitive  and  Transition 
crystalline  rocks  have  been  generated,  as  set  forth  in  the 
crenitic  hypothesis  *  already  explained  at  length,  in 
Essays  V.  and  VI. 

§  202.  The  Taconian  crystalline  rocks  "^'ere  deposited 
over  a  large  part  of  eastern  North  America  upon  the 
eroded  sui-faces  of  more  ancient  eozoic  groups,  and  in  their 
turn  suffered  greatly  from  movements  of  the  earth's  crust, 
and  from  erosion,  previous  to  the  beginning  of  Cambrian 
time.  Over  the  more  depressed  portions  of  the  worn 
surfaces  the  uncrystalline  sediments  of  Keweeniaii,  Cam- 
brian, Ordovician,  Silurian,  and  later  periods,  were  next 
successively  laid  down,  alike  on  the  Taconian  aiul  the 
more  ancient  crystalline  groups,  not,  however,  without 
intervening  movements  of  the  earth's  crust,  which  along 
the  eastern  portion  of  the  great  paleozoic  basin  caused 
stiratigraphical  breaks,  foldings,  and  partial  erosions  of 
these  later  groups  of  sediments.  Beyond  the  limits  of 
this  basin,  to  the  south  and  east,  the  sparse  distribution 
of  ai  IS  of  paleozoic  sediments,  and  their  absence  from  the 
highei  levels  among  the  crystalline  rocks  of  the  Atlantic 
belt,  permit  us  to  suppose  that  the  paleozoic  seas  did  not 
invade  these  higher  regions ;  while  the  deposits  made 
by  some  of  them  at  lower  levels  among  these  same  crystal- 
line rocks  have  been  in  great  part  removed  by  subse- 
quent agencies.  As  a  final  result  of  this  process,  we 
find,  within  the  great  basin,  the  Taconian  rocks  rest- 
ing on  various  older  crystalline  groups,  and  themselves 
overlaid  directly  by  various  paleozoic  secUments;  while 
outside  of  the   limits   of  the   basin,  areas   of   the   same 

*  "  All  physical  theories  properly  so  called  are  hypotheses,  whose  event- 
ual recognition  as  troths  depends  upon  their  consistency  with  themselves, 
upon  their  agreement  with  tlie  canons  of  logic,  upon  their  con:;ruenoe 
with  the  facts  which  they  serve  to  connect  and  explain,  upon  their  con- 
formity with  the  ascertained  order  of  Nature,  upon  the  extent  to  which 
they  approve  themselves  as  trustworthy  anticipations  or  i>r('visions  of 
facts  veriiied  by  subsequent  observation  or  experiment,  and  (iiitliy  upon 
their  simplicity,  or  rather  their  reducing  power," — btalio,  in  The  Con- 
cepts and  Theories  of  Modern  Physics,  p.  85. 


I  'I 


.Hi 


hi!  I 

'I 


680 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


m 


J 


Taconian  rocks  are  in  parts  overlaid  by  mesozoic  and  by 
tertiary  strata. 

§  203.  As  regards  the  existence  in  oth^r  lands  of  a 
similar  series  of  rocl<s  to  the  Taconian  of  North  America, 
we  have  seen  that  Lieber,  whose  independent  and  careful 
studies  of  this  series  in  South  Carolina  we  have  resumed 
on  pages  564-569,  supposed  it  to  be  the  stratigraphical 
equivalent  of  the  Itacoluniite  or  diamond-bearing  series 
of  Brazil,  of  the  similar  rocks  of  Bundelkhand  in  India, 
long  since  described  by  Claussen  and  by  Jacquemont,  and 
of  those  in  Russia,  where  several  areas  of  Itacolunnte 
rocks,  diamond-bearing  like  those  of  Brazil  and  India, 
were  discovered  in  the  southern  Urals  by  Ilelmersen 
and  Hoffman.* 

These  diamond-bearing  rocks  in  Bundelkhand  have 
since  been  described  by  the  geological  survey  of  India  as 
the  Lower  Vindhyan  series.f  The  studies  of  Hartt,  of 
Gorceix,  and  of  Derby  have  throAvn  farther  light  on  the 
Itacolumite  series  of  Brazil,  which,  according  to  the  latter, 
rests  unconformably  upon  the  older  crystalline  rocks,  and 
consists  in  great  part  of  quartzites,  often  granular  and 
sometimes  flexible,  with  unctuous  talcoid  schists  containing 
hydrous  micas,  chloritic  and  argillite  beds,  specular  schist- 
ose iron-ore  (itabirite),  and  great  masses  of  crystalline 
limestone.  The  resemblances,  long  since  noticed  by 
Lieber,  between  this  Brazilian  series  and  the  American 
Taconian  were  made  very  evident  by  a  collection  of  these 
rocks  from  the  province  of  Minas  Geraes,  examined  by 
the  writer  in  1876.  This  ancient  series  in  Brazil  has 
afforded  no  organic  remains,  but,  being  unconformably 

*  The  following  bibliographical  references  are  cited  from  Lieber: 
Eschwege,  Beitrage  zur  Gebirgskunde  Braziliens,  Berlin.  1832,  p.  174;  Spix 
and  Martins.  Relse  in  Brazilien,  XL  Theil ;  also,  Humboldt,  Gisement  des 
roches  dans  les  deux  hemispheres,  pp.  89-02;  Jacquemont,  Voyage  dans 
les  Indes,  1828-32,  Sur  les  grfes  schisteux  de  Panna  in  Bundelknnd,  etc. ; 
Cotta,  Gesteinslehre,  1855,  p,  212,  and  Zerrenner,  Gold,  Platin,  und 
Diamant  Waschen,  etc.,  Leipzig,  1851. 

t  Manual  of  the  Geology  of  Indi^,  Medlicott  aad  Blanford,  i  pp.  xxi. 
and  69-92.  . 


zoic  and  by 

lands  of  a 
th  An^.erica, 
and  careful 
ive  resumed 
i-atigraphical 
.living  series 
nd  in  India, 
^uemont,  and 

Itacolunnte 
L  and  India, 
y  Helmersen 

Ikliand    have 
f  of  India  as 
of  Hartt,  of 
light  on  the 
Y  to  the  latter, 
Ine  rocks,  and 
granular  and 
sts  containing 
secular  schist- 
of  crystalline 
noticed   by 
;he  American 
Iction  of  these 
examined  by 
n   Brazil  has 
nconformably 

led  from  Lieber: 
1832,p.n4;Spix 

|l(U,  Gisement  des 
mt.  Voyage  dans 
lundelkund,  etc.; 
old,  Platin,  und 

^nford,  i  pp.  xxl. 


XI.] 


TACONIAN   IN  FOREIGN  LANDS. 


681 


overlaid  by  older  paleozoic  rocks,  has  been  by  Derby 
supposed  to  be  altered  Cambrian,  while  others  liave 
•Assigned  it  to  a  pre-paleozoic  age.  The  diamonds  (wliich 
are  also  met  witli  in  derived  rocks),  are  found  in  the 
province  of  Diamantina  in  unctuous  banded  clays  of  vary- 
ing colors,  which  are  derived  from  the  sub-aerial  decay 
of  eastward-dipping  sl  '"stose  beds  of  the  Itacolumite 
group.* 

§  204.  A  close  resemblance  between  the  older  rocks:  of 
Brazil  and  those  of  Guiana  has  been  pointed  out  by 
Jannetaz,  who,  as  remarked  by  Crosby,  "  has  recognized 
in  the  latter  country  the  itacolumite,  with  the  hydromica- 
ceous  and  other  schists  of  the  former,  which  have  been 
connected  with  the  Taconian  system.  The  itacolumite  of 
Guiana  has  also  been  observed  by  Schomburgk."  f  Farther 
to  the  northwest,  beyond  the  mouth  of  the  Orinoco,  we 
meet  a  great  development  of  a  similar  series.  Crosby, 
writing  in  1880,  says  these  rocks  "constitute  the  main 
mass  of  the  great  eastern  branch  of  the  Andes,  or  at  least 
that  part  of  it  which  skirts  the  Caribbean  sea  from 
Caracas  eastward,  and  is  known  as  the  Littoral  Cordillera 
of  Venezuela."  The  Cordillera  forms  the  Northern 
Mountains  of  Trinidad,  which  have  an  altitude  of  3000 
feet,  and  terminates  in  the  neighboring  island  of  Tobago. 
These  semi-crystalline  rocks  of  the  Spanish  Main  and 
Trinidad  were  studied  some  twenty  years  since  by  Messrs. 

*  O.  A.  Derby,  On  the  Diamond  and  the  Itacolumite  Rocks  in  Brazil, 
1881  and  1882,  Amer.  Jour.  Science,  xxiii.,  97, 178,  and  xxiv.,  34-42;  and, 
in  abstract,  Rep.  Smithsonian  Inst.,  1882,  p.  332;  also,  Gorceix,  Gisement 
des  Diamants,  etc.,  Ridl.  Soc.  Gdol.  de  France.  1884,  xii.,  .').38-54.'5.  Derby 
supposed  the  Itacolumite  group  might  be  altered  Cambrian;  Gorceix 
thinks  it  may  be  Huronian. 

t  W.  O.  Crosby,  Notes  on  the  Geology  of  Trinidad,  1878,  Proc.  Boston 
Soc.  of  Natural  History,  xx.,  44-55;  also  farther,  on  the  Crystalline 
Formations  of  Guiana  and  Brazil,  1880,  ibid.,  xx.,  480-497,  in  which 
these  rocks  in  Trinidad  are  described  at  greater  length,  and  the  rela- 
tions of  the  Taconian  and  the  more  ancient  crystalline  series  In  North 
and  South  America  are  well  brought  out.  See,  for  an  analysis  of 
these  two  papers,  Hunt,  in  Report  of  Smithsonian  Institute  for  1882; 
pp.  330-333. 


m  i 


682 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


'I: 


pi 

1 

^1(1 1 

^1 

ij-ts 

pnlliy    ( 

i"! 

H^i^ 

L'^ 

feu 

Wall  and  Sawkins,*  by  vhom  they  were  designated  as 
the  Caribbean  group,  more  recently  by  R.  J.  Lechmere 
Guppy,  and  in  1878  were  examined  by  Crosby. 

§  205*  The  structure  of  the  Northern  Mountains  in 
Trinidad  is  monoclinai,  high  southerly  dips  being  uni- 
versal. The  thickness  of  tlie  strata  exposed  is  not  less 
than  10,000  feet,  included  in  three  divisions ;  a  lower, 
consisting  of  a  quartzite,  granular,  and  usuall})"  more  or 
less  micaceous,  followed  by  and  alternating  with  hydrous 
micaceous  schists  and  argillites,  often  lustrous;  a  middle 
one  of  several  thousand  feet  of  crystalline  limestones  in 
massive  beds,  varying  in  color  from  white  to  nearly  black, 
and  often  somewhat  micaceous ;  and  an  ujiper  division 
consisting  of  several  alternations  of  argillites  like  those  of 
the  first,  frequently  graphitic,  and  often  passing  into 
hydromicaceous  schists,  with  layers  of  quartzite,  some- 
times detrital,  and,  towards  the  summit,  thin  beds  of 
limestone.  The  whole  succession,  according  to  Crosby, 
strongly  resembles  the  Taconian  as  seen  in  western 
Massachusetts.  Overlying  unconformably  this  ancient 
series,  which  appears  to  be  unfossiliferous,  is  a  dark-colored 
compact  fossiliferous  limestone,  with  interbedded  shales, 
in  which,  among  many  obscure  forms,  Guppy  recognized 
Murchisonia  Anna  and  M.  linexris,  both  found  in  the 
Calciferous  Sand-rock  in  Canada. 

§  206.  Subsequent  observations  of  Crosby,t  in  1882, 
made  in  the  mountains  of  eastern  Cuba,  between  Baracoa 
and  the  southern  coast,  show  that  there  exists  to  the 
south  of  the  dividing  ridge  a  belt  six  or  eight  miles  wide  of 
highly  inclined  strata,  having  an  east  and  west  stiike, 
and  consisting  of  hydromicaceous  and  chloritic  schists, 
with  immense  beds  of  white  crystalline  limestone,  often 
micaceous.     This  group  is  entirely  distinct  from  one  made 

*  Wall,  Geology  of  Trinidad,  etc.,  1860,  Quar.  Geol.  Jour.,  xvi.,  660. 

t  W.  O.  Crosby  on  the  Probal)le  Occurrence  of  the  Taconian  in  Cuba; 
Science,  December  7,  1883,  p.  740;  also  in  abstract,  Hunt  in  Report  of 
Smithsonian  Institute  for  1883. 


Y. 


[XI. 


XI.] 


TACONIAN   IN   FOllEIGN  LANDS. 


G83 


lesignatecl  as 
J.  Lechmere 

yiountains  in 
)S  being  uni- 
id  is  not  less 
lis;   a  lower, 
lally  more  or 
with  hydrous 
)us;  a  middle 
limestones  in 
)  nearly  black, 
ipper  division 
5  like  those  of 
passing  into 
lartzite,  some- 
thin  beds  of 
ng  to  Crosby, 
a    in    western 
r   this   ancient 
a  dark-colored 
bedded  shales, 
ipy  recognized 
found  in  the 


sby,t  iw  1882, 
ween  Baracoa 

exists  to  the 
t  miles  wide  of 
d  west  sii'ike, 
iloritic  schists, 
mestone,  often 

'rom  one  made 


1 


Joiir.,xvl.,  C60. 
Taconian  in  Cuba; 
Hunt  iu  lleport  of 


up  of  fissile  slates,  soft  sandstones,  and  impure  earth}- 
limestones,  found  chiefly  on  the  northern  slope  of  the 
same  mountains,  and  regarded  by  him  as  probably 
equivalent  to  the  cretaceous  and  tertiary  strata  of  San 
Domingo  and  Jamaica.  Of  the  first-named  group  he 
says:  "These  rocks  bear  a  strong  resemblance  to  the 
Taconian  system  of  western  New  England,  and  are  essen- 
tially identical  with  the  great  series  of  semi-crystalline 
schists  and  limestones  of  Trinidad  and  the  Spanish  ^lain, 
which  I  have  elsewhere  correlated  with  the  Taconian." 
From  the  published  accounts  of  the  geology  of  San 
Domingo  and  Jamaica,  Crosby  conceives  that  these 
islands  have  a  similar  structure  to  that  of  southeastern 
Cuba.  Their  crystalline  schists  which,  according  to  him, 
have  been  generally  confounded  with  the  cretaceous  beds, 
he  believes  to  be  like  those  of  Cuba,  and  of  T.iconian 
age.  Cleve,  in  1870,  noticed  in  Porto  Rico,  Sa?  ta  Cruz, 
and  the  Virgin  Islands  an  unfossiliferous  series  which  he 
conjectured  might  be  metamorphosed  cretaceous.  These 
strata,  which  arc  vertical,  or  have  a  high  northern 
inclination,  consist  chiefly  of  argillites  and  crystalline 
lin  estones  like  those  of  Cuba  and  Trinidad.* 

§  207.  There  exists  in  the  Alps,  besides  the  ancient  or 
central  granitoid  gneiss  ( Laurentian),  the  great  pietre- 
verdi  series  proper  ( Iluronian  )  and  the  younger  gneiss 
and  mica-schist  series  (Montalban),  a  fourth  great  group, 
very  widely  distributed,  made  up  in  large  part  of  crystal- 
line schists,— the  argi^'  )-talcose  schists  of  Favre,  the  gray 
lustrous  schists  of  Lory,  the  sericite-schists  and  the 
glanzschiefer  of  others.  This  schistose  series,  to  which  a 
great  thickness  is  assigned,  includes  quartzites,  dolomites, 
micaceous  limestones,  banded  and  statuary  marbles,  ser- 
pentine,   talc,   karstenite,    and    gypsum.      These    rocks, 

*  P.  T.  Cleve,  Kongl.  Svcnska  Vetenskaps-Akadcniiens  Ilaudlingar; 
Banclet  9,  No.  12.  The  oretai-oous  ago  of  the  crystalline  schists  and  lime- 
stones of  San  Domingo  was  maintaiiu  d  by  Galib  In  his  memoir  oi  the 
Topograpliy  and  Geology  of  the  island,  etc.,  in  187:J;  Traas.  Amer. 
Philos.  Soc,  vol.  XV. 


It 


i 


w.\  i 


I      1 


684 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


nci. 


I 


which,  among  other  localities,  are  well  displayed  on  the 
line  of  the  Mont  Cenis  tunnel,  have  heen  by  many  Alpine 
geologists  regarded  as  altered  Jurassic  or  triassic.  This 
view  was,  however,  in  1872,  combated  by  the  present 
writer,  who  then  referred  them  to  primitive  or  eozoic 
time;  a  view  wiiich  has  since  been  accepted  by  Favre, 
who  had  previcnisly  regarded  them  as  mesozoic*  Their 
pre-paleozoic  age  was  afterwards  maintained  by  Gastaldi, 
by  Pillet,  and  by  Jervis.  I  have  since  called  attention  to 
the  fact  that  these  lustrous  schists  greatly  resemble  those 
of  the  Taconian  of  North  America,  to  which  I  have 
compared  this  whole  Alpine  series.  In  it  are  included, 
by  Gastaldi  and  Jervis,  the  schists  of  the  Apuan  Alps, 
with  their  crystalline  marbles,  all  of  which,  as  seen  in 
the  mountains  of  Carrara,  I  have  found  to  resemble 
closely  the  Taconian.  These  marbles,  it  may  be  re- 
marked, have,  like  those  of  the  American  Taconian, 
been  referred  to  very  different  geological  horizons,  having 
been  successively  called  altered  cretaceous,  liassic,  rhsetic, 
infra-carboniferous,  and  pre-paleozoic,  to  which  latter 
position  they  were  assigned  by  Gastaldi  in  1874. 

§  208.  To  the  same  horizon,  apparently,  belongs  the 
Hercynian  Primitive  Clay-slate  series,  which,  according  to 
Giimbel,  intervenes  in  Bavaria  between  the  Hercynian 
mica-schist  group  and  the  fossiliferous  Cambrian  stnata, 
by  which  it  is  overlaid.  This  clay-slate  series  includes 
beds  of  crystalline  limestone,  sometimes  magnesian, 
attaining  in  places  three  hundred  and  fifty  feet  in  thick- 
ness, which  contain  hornblende  and  serpentine,  and  a 
form  of  Eozoon  named  by  Giimbel  U.  Bavarieum.  It 
also  includes  siderite,  which,  by  epigenesis,  gives  rise  to 
valuable  masses  of  limonite.  The  history  of  the  group  of 
lustrous  sciiists  in  the  Alps,  and  their  related  rocks,  is 
discussed  at  some  length  in  the  fourth  part  of  Essay  X.,  to 
which  the  reader  is  referred  for  details  and  for  authorities. 

*  Hunt,  The  Geology  of  tlie  Alps,  Amer.  Jour.  Science,  vol.  iii.,  pp.  1- 
15;  also  Chem.  and  Geol.  Essays,  pp.  6^,  347,  348. 


XL] 


TACONIAN"  IN  FOltEIGN   LANDS. 


C85 


:e,  vol.  iii.,  pp.  1- 


Tn  some  parts  of  central  Norway,  tlic  fossiliferous  Cam- 
brian, or  so-called  Primordial  zone,  is  described  by  Kjerulf 
as  resting  directly  upon  the  ancient  gneiss,  but  in  other 
parts  it  is  underlaid  by  a  se'ies  which,  from  the  presence 
therein  of  detrital  beds,  is  designated  as  the  Sparagmite 
group,  and  sometimes  attains  a  thickness  of  over  2100 
feet,  as  in  Ostdalen.  This  underlying  series,  wliich  itself 
rests  upon  the  gneiss,  includes  red  and  gray  sandstones 
and  coiiglonierates,  with  considerable  masses  of  limestone 
and  of  dolomite,  besides  various  fissile  rocks,  described  as 
black  argillites,  lustrous  schists,  sometimes  talcoid,  and 
schistose  quartzites.  It  is  without  observed  fossils,  and 
has  been  by  Kjerulf  compared  with  the  Lower  Taconic* 

§  209.  The  recent  studies  of  Barrois  in  Spain,  pub- 
lished in  1882,  appear  to  throw  a  furtlier  light  on  the 
Alpine  series  which  we  have  compared  with  the  Taconian. 
The  paleozoic  rocks,  containing  at  their  base  an  abundant 
Canibriau  fauna,  are  found  in  the  province  of  Toledo 
resting,  according  to  Cortazar,  directly  upon  the  ancient 
gneissic  rocks,  but  in  the  Asturias,  between  these  Cam- 
brian strata  and  the  ancient  gneisses,  there  intervenes  a 
volume  of  not  less  than  3000  metres  of  strata,  described 
as  argillites  and  quartzites,  witli  dolomites  and  limestones, 
sometimes  saccharoidal  and  cipolin  marbles,  with  beds  of 
specular  iron-ore.  As  there  is  no  apparent  stratigraphical 
break  between  this  younger  crystalline  series  and  the 
strata  holding  the  first  fauna  of  Barrande,  the  name  of 
Cambrian  is  applied  by  Barrois  to  the  whole.f  The 
student  of  American  geology,  however,  recalls  the  inter- 
position between  the  Appalachian  Cambrian  and  the 
ancient  gneisses,  of  a  similar  great  series,  which  suggests 
that  in  this  region  of  Spain,  as  in  parts  of  the  Alps  and  in 

*  Hunt,  Azoic  Rocks,  p.  131,  and  Kjerulf,  Udsint  over  det  Sydllge 
Worges  Geologi,  1879,  pp.  128-138,  and  the  accompanying  Atlas,  plates 
xxvi.,  xxvii. 

t  Barrois,  Recherches  sur  les  Terrains  Anciens  des  Asturies  et  de  la 
Galice;  Lille,  1882;  4to,  pp.  C23. 


Iii 


■  n 
m 


M 


i.i 


I 


686 


THE  TACONIC  QUESTION  IN  GEOLOGY. 


[XI. 


Norway,  we  have  a  pro-Cambrian  group  corresponding  to 
the  American  Taconian. 

§  210.  It  has  been  tliought  well,  in  concluding  this 
essay  on  the  present  state  of  our  knowledge  of  the 
Taconian  series  in  North  America,  thus  to  bring  together, 
in  a  condensed  form,  the  principal  facts  with  regard  to 
certain  rocks  in  the  West  India  Islands,  in  South  America, 
in  Hindostan,  in  Russia,  in  the  Alps,  in  Bavaria,  in  Nor- 
way, and  in  Spain,  which  tend  to  show  that  in  all  these 
various  regions  there  exists  a  series  analogous  to  the 
Taconian  alike  in  mineral  and  lithological  characters  and 
in  stratigraphical  position.  Should  further  studies  con- 
firm this  view,  it  will  appear  that  the  Taconian  is  a 
great  and  wide-spread  group  of  strata  which  cannot  hence- 
forth be  overlooked  in  geognostical  history. 


APPENDIX. 


MiiiEUALOOicAL  Classificatkix.  It  has  been  shown  in  the  essay 
on  A  Natural  System  of  Mineralogy  that  tliffercnces  in  hardness  and 
specific  gravity  —  the  first  data  in  the  natural -history  method  —  are  inti- 
mately connected  with,  and  de-.  iideat  upon,  greater  or  less  complexity  of 
chemical  constitution.  The  arbitrary  cheu'ical  method  of  modern  min- 
eralogists is  thus  superseded,  and  a  new  chemistry  is  made  the  b<asis  of  a 
natural  system  of  classification,  in  which  the  chemical  and  natural-history 
methods  are  united  and  harmonized.  The  crystallographic  mineralogists 
have  assigned  to  crystalline  individualization,  whicli  is  but  an  accident  of 
certain  mineral  species,  an  importance  in  classification  that  has  often 
been  misleading.  The  principle  that  for  related  species  ^' the  luirdness 
and  chemical  indlfi'erence  are  inversely  us  the  value  of  V. ;  or,  in 
other  words,  tliat  they  increasi;  with  the  condensation"  (ante,  p.  ilU4), 
is  shown,  as  regards  tlvcir  chemical  relations,  in  the  case  of  meionite  and 
zoislte,  and  of  wollastonite,  amphibole,  and  pyroxene,  as  well  as  in  the 
various  carbon-spars,  when  treated  with  chlorhydric  or  nitric  acid,  and 
in  tridymite  and  quartz  with  solution  of  sodium-carbonate,  but  still  more 
striliingiy  in  the  behavior  of  silicates  v/ilh  lluorhydric  acid.  It  has  been 
noticed  (ante,  p.  214)  that  while  numy  silicates  are  readily  attacked 
thereby,  zircon,  staurolite,  amphibole,  pyroxene,  and  chrysolite  are  foimd 
to  resist,  more  or  less  completely,  its  action.  Mr.  J.  B.  Mackintosh  of 
the  School  of  Mines,  Columbia  College,  New  York,  having  tried  this  re- 
agent to  distinguish  between  certain  gems,  called  my  attention  to  the  in- 
difference thereto  of  garnet,  which  I  ascribed  to  its  great  condensation, 
and  suggested  comparisons  between  the  spathouls,  iolite  and  petalite.  on 
the  one  hand,  and  the  adamantoids,  epidote  and  spodumene,  on  the 
other,  predicting  that  the  first  two  would  be  attacked  and  the  last  resist 
the  action  of  fluorhydric  acid.  This  was  at  or-e  verifi(!d  by  the  trials  of 
Mr.  Mackintosh,  comnumicated  to  me  April  1),  188(5,  since  which  time  he 
has  greatly  extended  his  inquiries  in  this  direction.  lie  finds  that  while 
not  only  the  pectolitoids  and  the  zeolitoids,  but  various  spathoids,  such 
as  wollastonite,  the  feldspars,  scapolite,  and  leucite,  as  well  as  iolite  and 
petalite  (together  with  titanite  and  some  chloritic  species)  are  more  or 
less  corroded  Iw  the  acid,  the  adamantoids,  pyroxene,  enstatlte,  danburlte, 
garnet,  epidote,  zoisite,  axinite,  beryl,  tourmaline,  spodumene,  andalusite, 
topaz,  p.iid  cyanite  are  not  attacked  by  it.  He  has  farther,  at  my  sugges- 
tion, determined  the  rate  of  attack  with  equal  weights  of  various  sili- 
cates in  a  granulated  state  by  excess  of  dilute  fluorhydric  acid.  By  this, 
in  an  hour's  time,  there  were  dissolved  of  100.00  parts  :  of  albite,  23.00, 
of  petalite,  28.97,  of  iolite,  47.34,  of  oithoclase,  43.45,  and  of  leucite  63.30 

687 


'i'l 


¥ 


C88 


APrENDIX. 


parts;  wlillo  of  chrysolite  but  5.40,  and  of  quartz  but  I. SO  parts  were 
dissolved.  Of  opal,  under  .slndliir  conditions,  77.d8  j)arts,  and  of  a  yel- 
lowish noble  scrpcnllne  (sp.  j^r.  'J.-jil^)  S0.(I7  parts  were  dissolved;  show- 
ing, apparently,  a  gicat  siisccptiltillty  of  these  colloid  or  porodle  species 
to  the  action  of  the  acid.  Labradorite  and  oUgodase  were,  like  the  other 
feldspars,  readily  attacked,  but  the  separation  of  calcinni-fluorid  in  these, 
as  in  other  calciferous  silicates,  is  a  disturbini^  factor  in  (piantltatlve  ex- 
periments. Mackintosh  has  found  that,  w  bile  the  natiual  faces  of  ((uartz- 
crystals  resist  the  action  of  the  concentrated  acid,  their  cut  surfaces  are 
"eadily  attacked  by  it.  Of  these  Important  investigations,  now  in  progress, 
a  note  by  Mackintosh  appears  in  the  School  of  Mines  Quarterly  for  iluly, 
1880;  while  a  more  detailed  account  was  given  by  the  writer  In  a  "A 
Supplement  to  a  Natural  System  in  Jllncralogy  "  read  to  the  Uoyal  Society 
of  Canada,  May  2(t,  188(1,  and  published  in  vol.  iv.  of  its  Transactions. 

MiNKUAL<)(»iCAi<  NoMKNCLATUUK.  It  Is  evident  that  there  are  re- 
lations between  the  species  in  any  given  tribe  which  serve  to  unite  them 
in  families  and  genera,  but  which  our  present  trivial  nomenclature  falls 
to  Indicate.  Thus  the  large  family  of  the  feldspathldes  Includes  several 
genera,  one  of  which  —  the  true  feldspars  —  embraces  the  albite-anorthite 
series,  and  another — the  adularia  genus  —  with  a  less  condensation, 
orthoclase,  ndcrocline,  and  hyalophane.  In  the  same  tribe,  besides  the 
scapollte  genus,  which  comprebt'inls  the  nieionlte-marialite  series,  is  a 
group  of  related  silicates.  Including  niclllite,  humboldtlUte,  gehlenlte, 
sarcolite,  udlarlte,  and  baryllte,  which  will  form  a  cognate  genus.  To 
show  these  relations  aright,  a  Latin  binonual  nomenclature  is  needed, 
which,  with  the  new  system  of  cliissificatlon,  will,  it  Is  believed,  give  to 
mineralogy  a  form  and  a  completeness  hitherto  wanting. 

MiNEUAi.ooicAL  EVOLUTION.  The  laws  which  have  presided  over 
the  differentiation  of  the  primeval  chaos,  and  pro  :  need  the  various 
groups  of  rocks,  alike  exotic,  endogenous,  and  indigenous,  which  have 
determined  the  progressive  changes  In  chemical  constitution  from  the 
ante-gneissic  granite  down  to  the  youngest  crystalline  schists  and  the 
detrltal  sediments  of  later  times,  are,  as  we  have  sought  to  show,  not 
less  certain  and  definite  than  those  which  preside  over  astronondcal  and 
biological  development.  The  great  successive  groups  of  stratiform  crys- 
talline rocks  mark  necessary  stages  In  the  mineraloglcal  evolution  of  the 
planet  {aute,  pp.  113,  184,  253,  678).  The  facts  already  discussed,  of  the 
continued  generation,  down  to  the  present  time,  of  certain  silicates  In  the 
channels  of  thermal  springs,  in  deep-sea  ooze,  in  fossllifcrous  limestones, 
in  the  interstices  of  detrital  rocks,  and  often  in  proximity  to  intrusive 
Igneous  masses,  afford  no  justification  of  tlie  hypothesis  of  regional  meta- 
morphlsm,  which  seeks  the  origin  of  the  unlike  groups  of  crystalline 
eozolc  strata  In  some  unexplained  and  Inexplicable  transmutation  of 
different  portions  of  one  and  the  same  series  of  ordinary  detrltal  sedi- 
ments of  paleozoic  or  more  recent  times.  The  supposed  examples  of 
such  a  process  have  one  by  one  been  disproved  and  abandoned  by  their 
former  advocates,  who  had  substituted  the  Intervention  of  miracles  for 
the  orderly  and  established  process  of  mineraloglcal  development. 


■e  presided  over 
ced  the  various 
nis,  which  have 
union  from  the 
schists  and  the 
;ht  to  show,  not 
strononiical  and 

stratiform  crys- 

vohition  of  the 

liscussed,  of  the 

n  silicates  In  the 

ous  limestones, 
nity  to  intrusive 
)f  regional  meta- 
)s  of  crystalline 
■ansmutatlon  of 
iry  detrital  sedl- 
led  examples  of 
mdoned  by  their 

of  miracles  for 

opment. 


INDEX. 


AniornYsioi.ooT  deflncd,  21. 

AtMiilto,  i;i7,  M<X 

Ailiiins,  <;.  H.,  t,'»-'"l<>Ky  of  Vormont,  030. 

Adiromliick  :Muuiitaiii8,  403,  0'22. 

Ae^lritf,  .11!). 

Ai'riiil  ili'iuiiliitiiiii,  27.5. 

Agftti's,  l'l;i>  fair  ou,  74. 

Agrlciillte,  ;it!ii. 

Alubiiiim,  (;o()lo(,'y  of,  357,  noO,  503. 

AlbercKo,  -liHi. 

Alburtl,  cniptivo  rdck-.snlt,  00, 

Alblte,  arlitlnial  fcinuiillon  of  157,  605. 

Ali'xaiidriii,  sidiiidl  of,  'J. 

Alkaliiif)  Hilk'.ilii)  in  toniiatlou  of  oxyda, 
ir>0,  181,  2»i). 

Alkaliiio  waters,  218,  note, 

AUaiiito  gr(iu|i  of  tilllcati'S,  346. 

AUiiian,  protoplasm,  IH. 

Ali>s.  —  Apuaii,  473,  477,  JS3,  084;  East- 
ern, 4fi.'>  et  .1(7/. ;  LiRurian,  475  ;  Mari- 
time, 473,  47."> ;  Wt'Storn,  45H  et  .lei/.,  48.') ; 
general  nooloKy  of,  457  rt  ««(/.,  083  et 
aeq.;    (iastaldi    on,   45H   et   arij.,   4.81; 

I  Gerlacli  on,  4,")9,  407  ;  Von  Hauer  on, 
45!l,  40.'),  471,  481 ;  Lory  on,  4(!0  el  seq.; 
Staplf  on,  470  et  get/. 

Altered  (.'liamplain  division, 008,  0.55,  O.'i0, 
057  ;  (.)uol)cc  (,'roup,  400,  410,  010;  Ulld- 
Bon-KiviT  group,  JOG,  000. 

Alundna,  relal  ions  of,  100,  300. 

Alundnoiis  silicates,  37,  IL'0, 1,53,  100,  183; 

•  dissooiiUion  of,  148,  1,")0,  240. 

Andantlioiil  silicate  from  Portsmouth, 
.  K.  I.,  19.5,  ,?,5!t. 

Amorphite,  order  of,  Weisbach,  .381. 

Amphibole,  147,  310;  its  relations  to 
woUastonite  and  jiyroxene,  290,  330. 

Amphiniorphic  rocks,  485,  487. 

Aniygdaloids  of  Faroe  Islands,  l.'!5. 

Analcito,  artlticial  formation  of,  157,  505. 

Anaxagorns,  4,  7. 

Ancient  gneiss.  See  Gneiss,  older  or  cen- 
tral. 


689 


Andaliislto,  3t.fl,  412,  478. 
Angli'ney,  geology  of,  1 11-1,  417. 
Anindkie  group  of  rooks,  411,  578  ct  $cq.f 

Oil,  01,'!. 
Antliiaeoids,  tribe  of,  .380, 
Antliraciie  of  Pennsylvania,  Oil,  521  ;  of 

Itliode  Nland,  105,  X,{), 
Antlipiity  of  rock-doeay,  2,50,  200. 
Apatite,  In  <-'anada,  225  el  sii/.;  veins  of 

descritpi'd,  1/32  ;  in  Norway,  2.10. 
Apennlnei,  geology  of,  l,"(>  it  w/.;  .lor- 

vis  on,  t77  ;  (ia^*laldi  on,  48;!. 
Appalaelii;in  valley,  linionilis  of,  201  et 

nei/.,  5,15  ;  Taeoniaii  in,  ,5,"i0  ;  Cambriau 

of,  ,580,  020. 
Apuan  Alps.    See  .Mps,  Apuan. 
Arab  pliysicians,  10. 
Arago,  tile  inttM-steiiar  medium,  03. 
Areluean  or  ICo/.oie  roeks,  01,  402. 
Ardennes,  gi^ology  of,  A'2i  ;    wlietstonea 

of,  425,  .t.ile. 
Ardennile,  a  vanadosilicate,  347. 
Arenig  roeks,  t!25. 
Arfvedsonite,  .'!4!t. 
Argiliite,  Transition   of   Katon,  519;   it 

und(Tlios  tlie   First  Graywacko,  587; 

in  Minnesota,  ,578,  ,580. 
Argilloids,  tribe  of,  318  ;  table  of,  370. 
Aristotle,  1,  2,  :i. 

Arizona,  geology  of,  014,  024  et  seq. 
ArsenopyriloiilH,  tribe  of,  378. 
Arvonian  roeks,  409;  AVales,  418  c^  .'"''7.  ,' 

Pennsylvania,  540  (7  seq.;  Wiseonsin, 

540;  Mlsso\irl,  103,409;  Atlantlecoast, 

408  e^  .'I''/.,  547;  Scotland,  424  ;  possibly 

in  the  Alps,  515,  nule. 
Ashburner,   C.   A.,    anthracite    seams, 

611. 
Asphaltolds,  tribe  of,  380. 
Astronomy,  its  object,  27. 
Astrophyllite,  a  zireonle  niiea,  355. 
Atlantic  belt,  decayed  rocks  of,  250  el  aeq,; 

Messrs.  Uogers  on,  544,  001. 


)  ;; 

1 

\ 

,J 

t 

:ti 

■  1 

■  ( 

t1 

f 


I 


i 


•!«3 


mW- 


mm 

■ 

WS^*'' ' 

t  ,    'i 

^H 

MLJ 

'      v« 

1 

iy 

--'-9 

j  M 

^H&<    *l 

'  rf  '  w 

tjpif^ 

G90 


INDEX. 


Atmosphere,  cliomical  and  geological 
relations,  of,  30  et  scq.  ;  composition 
ami  weight  of,  31  ;  Hecular  changes  in, 
34;  relations  of  to  climate,  43  e<  sej.; 
to  a  cooling  planet,  47. 

Atomic  formulas,  i.'U2  ;  notation,  302  et 
seq,,  31!) ;  weiglits,  table  of,  320  ;  sym- 
bols, ibid.!  volumes  (see  Molecular 
volumes). 

Auerbachite,  .300. 

Augite.    See  Pyroxene. 

Auriferous  gravels  of  California,  272. 

Auroral  lime;  one  of  Hogers,532  et  seq.  ; 
thickness  oi,  037, 041. 557  ;  in  Alabama, 
557  J  is  Tacoiiiaw,  532,  535;  Lingula  of, 
582. 

Axinite,  138,  347. 

Azoic  series  of  Uogers,  405,  544,  6C1 ;  of 
Foster  and  Whitney,  405. 

Bac.inqtonitk,  340. 

Bacon,  Francis,  on  activity  of  matter, 
20,  note. 

Bailey,  L.  W  ,  geology  of  New  Bruns- 
wick, 407. 

Bandeil  structure  in  eruptive  rocks,  201, 
210  it  seq.  ;  in  veins,  224  et  seq.  See 
Lamination  and  Veinstones. 

Barabno  Kiver,  Wisconsin,  54(5. 

Earlier,  G.  F.,  life,  lit. 

JJarranile,  .1.,  the  Taconic  system,  635. 

Barrois,  Ch.,  geology  of  Spain,  085. 

Barsowite,  142. 

Basic  rocV.s,  secretions  of,  134, 135 1<  seq., 
220,  ,307. 

Basalt,  Mutton  on,  74 ;  suggested  origin 
of,  116,  207;  of  Colorado,  135;  Bun- 
sen's  normal,  129, 189,  212  ;  Durocher's, 
212. 

Bastard,  unt.,  conglomer.ates  of,  577. 

Bauxite,  376 ;  its  relation  to  corundum, 
604. 

Becker,  O.  F.,  cited,  294  ;  law  of  cooling, 
245,  note. 

Bccraft's  -Mountain,  032. 

Belir,  Arno,  dextrose,  504. 

BeloBil  :\Iountain,  005,  632. 

Belt,  Thos.,  eruptive  quartz,  95;  min- 
eral veins  ibid.;  death  of,  ibid,,  note; 
displacement  of  decayed  rocks,  275, 
note. 

Beroldinger,  granite,  82. 

Borthier,  rock-tlecay,  31, 

Berkshire  Co.,  Mass.,  geology  of,  653  et 
seq. 


Beryl,  its  fusion,  290,  note;  analyses  of, 
347  ;  change  to  kaolin,  370. 

Berzelius,  artificial  formation  of  zeolites, 
155  et  seq. ;  chemical  system  of  miner- 
alogy, 282  et  seq. ;  dynanuds,  13, 

Bieilese,  Italy,  ancient  gneiss  of,  402  ; 
pietre  verdi  of,  ibid.;  younger  gneiss  of, 
403  ;  syenite  of,  ibid. ;  serpentine  of, 
496. 

Bigsby,  J.,  Huronian,  407  ;  two  series  of 
crystalline  rocks,  600. 

Billings,  E.,  Lower  I'otsdam,  618, 624,038  ; 
Cambrian  of  Nowfounilland,  025  ;  Levis 
limestone,  618, 633 ;  Ordovician  of  Farn- 
ham,  606  ;  section  to  Bridport,  Vt., 
605. 

Biotic  (Biotics),  17,  18,  28;  relatio'-  to 
organograt)hy,  2»<5. 

Biology,  its  object,  17. 

Biophysiology,  21. 

Birdseye  limestone  of  Eaton,  526. 

Bischof,  G.,  metasomatism,  83,  103,  200, 
498. 

Bismuthic  oxyd,  306  ;  silicates,  322,  365. 

Bismutoferritc!,  .360. 

Blair  Co.,  Ptnn.,  geological  section  In, 
537. 

Blake,  W.  P.,  calcareous,  veins,  229; 
rock-decay,  248. 

Biake,  T.  M..  and  Johnson,  kaolin, 
369. 

Blue  Rl^lge,  decayed  rocks  of,  251,  258; 
geology  of,  656,  .559  et  seq. 

Boltonitfa,  507.    .SVe  Chrysolite, 

Bomlvshell  ore,  its  origin,  202. 

Bonney,  T.  G.,  serjientines  as  igneous, 
4i0etseq.;  Ihorzolite,  508 ;  metasoma- 
tism, 407,  note;  metamorphism,  Ofis  ; 
serpentines  of  Cornwall,  Eng.,  449  ;  of 
Italy,  452,  495  ;  of  Scotland,  510 ;  ser- 
pentine breccias,  453. 

Bornemann,  geology  of  Sardinia,  476. 

Borates,  water  inrfused,  220. 

Borosalinoids,  tribe  of,  380. 

Boric  oxy<l  in  silicates,  .300,  330,  350. 

Botzen,  rocks  of,  515,  iinte. 

Bournonoids,  tribe  of,  ,378. 

Boue,  A.,  cited,  95,  477,  notes;  metamoi- 
phisni,  82. 

Boulders  of  decomposition,  183,  247  it 
seq.,  252,  257,  272,  276. 

Bowcnite,  332. 

Boyerstown,  Penn.,  iron-ores  of,  551. 

Brazil,  geology  of,  564;  Tucouian  In,  680; 
diamonds  in,  681. 


INDEX. 


G91 


!ih 


9,  note ;  analyses  of, 
olin,  370. 

fonuiitlon  of  zeolites, 
cal  systwn  of  ininer- 
ilynainiils,  13. 
!ieiit  gneiss  of,  402  ; 
(/.;  younger  gneiss  of, 
ibid.;   serpentine  of, 

in,  407  ;  two  series  of 

6ti0. 

I'otsilnm,  018,624, 638; 

founiiland,  025 ;  Levis 

I;  Ordoviciau  of  Farn- 

ju  to   Bridport,  Vt., 


)  of  Eaton,  526. 
loniatism,  83,  103,  200, 

86  ;  silicates,  322,  365. 
B. 
geological  section  In, 

alcarcouL   veins,   229; 

,nd    Joliiison,    kaolin, 

yed  rocks  of,  251,  258; 
')59  I't  neq. 
PC  Chrysolite, 
s  origin,  262. 
erpentiiies  as  igneous, 
solite,  508;   nietasoina- 
nictainor|)liism,  668  ; 
ornwall,  Eng.,  440  ;  of 
of  Scotland,  510  ;  ser- 
i,  453. 

)gy  of  Sardinia,  476. 
.fused,  220. 
lie  of,  380. 
ratos,  306,  330,  350. 
515,  rinte. 
le  of,  .378. 
5,  477,  notes ;  metanior- 

miposition,  183,  247  ft 
•2,  276. 

II.,  iron-ores  of,  551. 
,•",64;  Tucouian  In,  680; 


Bravaisite,  164,  vote ;  362. 

Brewster,  D.,  on  Xewton,  52,  59. 

Ilreithaupt,  A.,  Mineralogy  of,  281 ; 
porodic  or  coHoid  species,  383 ;  or- 
ders of  silicates  of,  ibid. 

Bricks,  changed  by  hot  water,  152. 

Bridport,  \  t.,  geological  section  to,  005. 

Britton,  N.  L.,  geology  of  Staten  Island, 
209,  411. 

Brodie,  B.,  ideal  elements,  52  et  seq. ;  the 
chemical  process,  397. 

Brongiiiart,  A.,  chemistry  of  the  atmos- 
phere, 30  ;  eruptive  iron-ores,  96  j  ser- 
pentine, 428. 

Broinids,  sub-order  of,  380. 

Brooks,  T.  B.,  mica-schists  of  Michigan, 
580 ;  rocks  of  St.  Lawrence  Co.,  Kew 
York,  576. 

Broolts,  T.  B.,  and  Pumpelly,  on  Kewee- 
iiian,  614. 

Brown,  Thos.,  mental  physiology,  5. 

Briigger  and  Ueusch,  igneous  origin  of 
apatite  veins,  236  ;  chrysolite,  508. 

Bruce  Mines,  Lake  Iluron,  metalliferous 
veins  at,  122. 

Bunsen,  K.,  trachytic  and  pyroxenic 
rocks,  87, 129, 207,  212  ;  the  earth's  inte- 
rior, 87 ;  palagonitr    129,  130  (note),  159. 

Burbank,  L.  S.,  crystalline  limestones, 
230 ;  rock-decay,  252. 

Burke,  Edmund,  physiology,  4. 

Bytownite.    See  Barsowite. 

Calapuia,  rocka  of,  483. 

Calcareous  veinstones,  224  et  seq.,  2.30. 

Calciferous  Sand-rock,  521  et  se^.,  526,  595, 
617  et  Keq. 

Caledonian  rocks,  670. 

California,  rock-decay  in,  272 ;  auriferous 
gravels  of,  ibid. 

Callaway,  nietaniorphisni,  008  ;  Scottish 
Highlands,  670. 

Cambrian,  Sedgwick  on,  624,  028  r  Ameri- 
can divisions,  623  et  siq. ;  Atlantic 
coast,  407,  573,  577,  623  ;  Apiiaiachiaii 
area,  626,  677  ;  eastern  Xew  York,  003, 
639  et  seq.;  thickness  of ,  0,39  ;  Adiron- 
dack area,   622,  027;  Mississippi  area, 

623  ;   Utah  and  Nevada,  ibid. ;  Texa.i, 

624  ;  Xewfoundland,  025  ;  Sardinia,  470 ; 
Bavaria,  681 ;  relations  to  Keweeuian, 
621,  025. 

Cambridge,  Eng.,  philosophical  society 

of,  67. 
Campbell,  J.  F.,  glaclation,  64. 


Cancrinite,  343. 

Cannizaro,  atomicity,  292. 

Capacci,  Italian  serpentines,  488  et  stq., 
489  et  3cq. 

C.arb.ites,  sub-order  of,  380. 

Carbhydrates,  sub-order  of,  380. 

Carbon,  chemistryof,  288  ;  carbon  serios, 
the,  ibid.;  elemental  unit  for,  391  ;  in 
Laurentian  rocks,  109;  amount  of  in 
earth's  crust,  35  et  seq. 

Carbonic  acid.     See  Carlwnic  dioxyd. 

Carbonic  dioxyd;  sources  of,  38  e/  siq., 
66  ;  amount  in  eartli's  cr\ist,  30,  60  ;  its 
reduction  and  lixation,  ,'!4, 37  ;  in  inter- 
stellar space,  40, 00 ;  in  auriferous  grav- 
els, 273. 

Carbonate  of  lime,  its  origin,  30,  178,  239, 
253;  solubility  of,  lOH  ;  replaced  by 
carbonate  of  iron,  200  et  xeq. 

Carbon  spars,  289  et  seq.,  687  ;  molecular 
weight  of,  385. 

Carnarvonshire,  Eng.,  rocks  of,  417,  418. 
419. 

Carpenter,  W.  B.,  11 ;  life  in  matter,  10, 
note. 

Carrara  marble.',  ?i5,  473,  477,  684. 

Caribbean  group  of  rocks,  682. 

Celestial  chemistry,  41  et  seq. ;  UO  et  seq. 

Cerium-metals,  oxalates  of,  1(19. 

Chabazite,  159  ;  amorphous,  151. 

Champlain  division,  521,  599,629  ;  altered, 
608,  Ooo,  050,  057. 

Chance,  section  at  Delaware  ^Vater-Oap, 
538. 

Chaotic,  rocks  of  Werner,  71 ;  hypothesis 
of  crystalline  rocks,  s4,  10,5,  109. 

Characteristic  in  mineralogy,  313. 

Charnwood,  ICng.,  rocks  of,  421. 

eiiazy  limestone,  .VJl,  618,  019,  029  ;  sand- 
stone. Oil,  023. 

Chemical  process  defined,  397;  Hfgel  on, 
15,  397  ;  Brodie  on,  52  et  seq. 

Cheniism,  13  et  seq.;  397. 

Chemical,  homologies,  2S5,  289,  291,  394  ; 
units,  .)1M)  et  seq.;  indifference,  related 
to  condensation,  2n0,  299,  304,  (J.s". 

Chemistry,  newdeparture  in,  2Ki>, ;is9, 087 ; 
in  mineralogical  dasr-ification,  285  et 
scf/.,  318,  ,'189;  of  prinievii!  earth,  114, 
117;  its  relation  to  physics,  15  et  seq,, 
390. 

Chester  Co.,  Penn,,  serpentines  of,  437  et 
seq.;  limestones  of,  519, 

Cl.ickis,  I'enn.,  section  at,  644. 

Chlorids,  sub-order  of,  380. 


ih 


f! 


692 


INDEX. 


Chlorites,  355  et  seq. 

Chlorine  in  silicates,  293, 303, 324, 341, 342, 
344. 

(;hoii(lr.,.'-te,  145,  328,  507. 

Chromic  minerals,  436,  508. 

Chrysolite,  92,  100,  101,  145;  sub-aerial 
decay  of,  505  ;  relation  of  to  serpen- 
tine, 450, 503,  505 ;  formed  from  serpen- 
tine, 500,  513;  by  igneous  fusion,  209, 

219,  220,  333,  506  ;  by  aqueous  action, 

220,  ,504,  ,507  et  set}.,  513,  510 ;  roclia  of 
Norway,  508  ;  of  Nortli  Carolina,  ibid., 
560  ;  of  the  Pyrenees,  .TOS  ;  of  New  Zea- 
land, ihiff. ;  of  Mt.  M.a,  .509 ;  of  Saxony, 
479 ;  in  dolerites,  211,  506  ;  analyses  of, 
212  ;  in  lav^vs,  213. 

Chrysotile,  .324,  4.53. 

Church,  A.  H.,  density  of  zircons,  366. 

Cicero  on  phy.siology,  2. 

Cipolliiio  marbles,  ,5.54,  674. 

Clays,  genesis  of.  254,  308.  ,370  et  aeq. 

Clarke,  P.  W.,  cosmic  evolution,  47,  55. 

Classes  in  mineralogy  defined,  .382. 

Clerk-Maxwell,  dissociation,  ,54. 

Cleve,    geology    of    Porto    Rico,   etc., 

683. 
Cleveland,  P.,  Werner's  mineral  system, 

280,  note. 
Clitford,  W.  K.,  dynamics,  13 ;  molecular 

motion,  15. 
Coal-seams  displaced,  511. 
Cobalt  in  iron-ores,  .5.36.  .5,53,  569, 
Cobalt-ammonias,  386.  392 
Cobequld  Hills,  geology  of,  573. 
Coldbnt  k  rocks,  407  et  seq. 
Colloids,  314,  316  et  seq. :  relation  of  to 

life,  18   et    seq. ;    sohibility  of,    168 ; 

changed  to  crystalloids,  375 ;   igneous 

and    aqueous,  362,   374   ft   neq.,   383 ; 

limits  of  species  in,  398.    See  Porodini 

and  Porodic. 
Colloidal  rocks,  192  ;  liquids,  221. 
Colorado,  Table  Mt.,  135  ;  granitic  veins 

of,  223  :  Grand  Caflon  of  the.  624. 
Conglomerate,  in  ancient  rocks,  110, 183, 

2.54  et  seq.,  479,  577. 
Contraction  of  cooling  globe,  241. 
Connecticut,  rock-decay  In,  248  ;  granite 

in,  211,  no^e. 
Concretionary  rocks,  222V/  seq.,  234. 
Condensation  in  mineral  species,  166, 285 

et  seq.,  305, 390  et  seq.,  391,  687 ;  relation 

Of  to  hardness,  285,  299,  .304,  395;   to 

chemioul  indifference,  286,  299,  304,  395, 

687. 


Cook,  G.  H.,  618;  geology  of  New  Jersoy* 
670,  590  et  seq.,  658. 

Copper,  ores  of  in  Blue  Ridge,  268  et 
seq.;  mesozoic,  260;  theory  of  its  con- 
centration and  depo'dtion,  259  et  seq,; 
native  with  zeolites,  139;  in  Keweenian, 
260. 

Corniferous  limestone  of  Eaton,  527. 

Coronite,  a  mag-iesian  touriualine,  162, 
350. 

Corrugation  of  crystalline  strata.  111,  179, 
241,  243. 

Corundum,  100 ;  genesis  of,  239,  240 ; 
artificial  production  of,  300  (note),  504. 

Cordier,  origin  of  lime-carbonate,  36. 

Corsica,  rock-deoay  in.  276  ;  serpentinea 
of,  474  ;  granites  of,  475. 

Cornwall,  Eng,,  cryst.nlline  rocks  of,  449  j 
serpentines  of.  ■)'"<,  449.  510. 

Cornwall,  Penn.,  iron-ores  of.  5.''6  (note), 
650  et  seq. ;  serpentines  of,  442. 

Cosmic   evolntinn,  47,  ,5.-;,  .56.  59  ;  dust,  61. 

Cossa,  It.ilian  serpentines,  4,54,  484. 

Cosmos,  the.  26,  vote:  Humboldt's,  22.  " 

Cotgrave,  physiology,  3. 

Coticulite,  Rt^nard  on,  425.  note. 

Crenitic  hypnihesis  of  crystalline  rocks, 
132  et  seq.,  175.  216  et  seq,,  199,  2.38,  241, 
673  ;  action,  chances  by,  in  plutonio 
rocks,  216  ;  in  crenitic  rocks,  186,  217  ; 
compared  with  eliquation,  217. 

Crediier.  H..  405  :  geology  of  Saxony,  256, 
479  ;  of  Lake  Superior,  581. 

Crinoids,  silicntes  in,  193  et  seq. 

Crosby,  W.  O.,  geology  of  West  Indies, 
681  et  seq. 

Cross  and  Hildebrand,  zeolites,  135  e/  seq. 

Crystalline  admixtures,  294,296,  ,304.  342. 

Crystalline  rocks  defined,  191  ;  origin  of, 
68  et  seq. :  various  hypotheses  regard- 
ing, 82  et  seq..  104 ;  a  new  hypothesis, 
112  et  seq. ;  three  propositions  relating 
to,  125;  universality  of,  107,  110;  au- 
thor's early  studies  of.  112;  succession 
in  time,  106,  678,  OSS  ;  .secular  changes 
in,  187;  great  groups  of,  1S4  ;  inclined 
strata  an<l  corrugation  of.  111,  179,  241 
etseq. ;  concretionary  cliaractcr  of  (see 
Concretionary  rocks);  conglomerates  in 
(see  Conglomerates,  etc  );  genetic  his- 
tory of  (see  190  et  seq.);  decay  of  (see 
Decay  of  rocks'). 

Crystalline  silicates  in  organic  forms,  193 
et  seq. 

Crystallophyllian  rocks,  8tf. 


INDEX. 


G93 


ology  of  New  Jersoyi 

i. 

I  Blue  Kidge,  258  et 

iO ;  theory  of  its  con- 

epoitioii,  259  et  seq.; 

es,  139;  in  Keweenian, 

:)ne  of  Eaton,  527. 
isian  touriualine,  162, 

jtalline  strata,  111,  179, 

penesis   of,   239,   240; 
Hon  of,  300  (nntv),  504. 
linie-carbouate,  36. 
y  in.  276  ;  serpentines 
I  of,  475. 

ystalline  roclJS  of,  449 ; 
"^.  449.  RtO. 

iron-ores  of,  5?6  {note), 
entincs  of,  442. 
47,  W,  .W.  59;  dust,  Bl. 
f)pntincs,  454,  4S4. 
ole:  Humboldt's,  22.  ' 

^gy,  3. 

I  on,  425.  vote. 
is  of  crystalline  rocka, 
210  et  scv.,  199,  238.  241, 
lancps  by.  in  plutonio 
renitic  rocks,  186,  217  ; 
■liquation,  217. 
ppolofiy  of  Saxony,  255, 
perior,  5S1. 
in,  193  et  neq. 
sology  of  West  Indies, 

and,  zeolites,  nfietseq. 
tures,  204, 296,  304,  342. 
defined,  191  ;  origin  of, 
nns  hyiiothoses  regard- 
104  ;  a  new  hypothesis, 
e  propositions  relating 
sality  of,  107,  110;  au- 
iliosof,  112;  succession 
,  r,s8  ;  secular  changes 
roups  of,  1S4  :  inclined 
ugation  of,  111,179.  241 
onnry  character  of  (.nee 
•orl(s);  conglomerates  in 
ates,  etc  );  genetic  his- 
et  seq.) ;  decay  of  (see 

tes  in  organic  formB,  193 


Crystallization,  conditions  of,  167  et  seq., 

173  et  seq. 
CrysialUiio  form,  320  ;  its  significance  in 

mineralogy,  37H,  3X3,  (iSS. 
Cuba,  geology  of,  683. 
Cudwortli,  physiology,  4. 
Cyaiiite,  101,  .366,  478,  503. 
Cycles  in  sedimentation,  618,  627. 

D.=DF.xsiTY  or  specific  gravity,  304,  .301. 

Dale,  T.  N.,  fossiliferoiis  rocks  of  Hudson 
valley,  642. 

Daniour,  A.,  jadeite,  301. 

Pamourlte,  .357  ;  schists,  161,  26,3. 

Dana,  E.  S.,  Textrbook  of  .Mineralogy, 
2S3. 

Dana,  J.  D.,  combiner^,  volcanic  and  meta- 
morphic  hypothesis  of  crystalline  rocks, 
89  et  seq.,  201;  Archa>an  roclis,  91 ;  erup- 
tive granites,  90;  a  heated  ocean,  j /«V/. ; 
eruptive  limestones,  90, 228;  pseudomor- 
phism, 100,  101,  note;  pinite,  in?.,  10.'); 
his  .System  of  Mineralogy,  282  ;  .adopts 
and  then  rejects  tlie  >;atural-IIistovy 
method,  282  et  seq. ;  atomic  volumes, 
303,  note  ;  metamorphism.  063  ;  grades 
in,  065,  678  ;  crystalline  rocks  of  .soiilh- 
eastera  New  York,  663  ;  his  arguments 
examiued,  665  ;  liis  citations  of  Messrs. 
Rogers,  664;  Taconian  rocks,612  ef  seq.  ; 
Taconic  literature,  673,  note;  Gray- 
■wacke  series,  651. 

Dana,  J.  F.  and  S.  L.,  rock-decay,  247. 

l>arton,  N.  H.,  Green-Pond  Mountain, 
X.  J.,  591. 

Darwin,  Charles,  laminated  rocks,  201  ; 
rock-decay,  250. 

Daubr^e,  A.,  Hutton's  system,  70;  the 
origin  of  crystalline  rocks,  78,  86  ;  the 
primeval  ocean,  79  ;  decomiiositicm  of 
glass,  147  et  seq. ;  alteration  of  bricks, 
152  ;  artificial  production  of  pyro.xene, 
quartz,  and  mica,  149  et  seq. ;  miner- 
alogy of  thermal  springs,  150  et  seq. 

Davidson,  Thos.,  Rosmini,  16,  note. 

Dawboii,  J.  W.,  on  silicates  in  organic 
forms,  193  et  .teq. :  Kozoiin,  231,  573,  ,575, 
676  ;  a  fossil  sponge,  678  ;  organic  forms 
from  Hastings  rocks,  575  et  seq. ; 
Eozoic  rocks,  402  ;  Cobequid  Hills,  573  ; 
Keweenian,  012. 

Decay  of  rocks,  31  et  seq.,  127,  246  et  seq., 
677;  Hoosac  Mountain,  2.'i6 ;  Connecti- 
cut, 249  ;  Pennsylv.inia,  251  ;  Georgia, 
258;  Blue  Ridge,  251,  258;  Corsica  and 


Norway,  276  ;  limestones,  249,  250,  205, 
porphyry,  209  ;  serpentines,  208,441; 
dolerite,  271 ;  auriferous  gravels,  i;7-  ; 
preliminary  to  erosion,  252,  277  ;  bould- 
ers formed  by,  183,  247  et  seq.,  254,  257, 
272,  276,  278. 

Deerfield,  Ma.ss.,  diabase  of,  138,  1.30. 

Delaware  \Vater-(iap,  sections  at,  538, 

Delesse,  A.,  ou  crystalline  admixtures, 
204;  origin  of  serpentines;  liis  earlier 
and  later  views,  431  et  seq. ;  luetamor- 
pliisin,  432. 

De  Luc,  aqueous  origin  of  rocks,  69. 

De  la  Beohe,  therniochaotic  hyiiothesis 
of  crystalline  rocks,  77  et  seq.  ;  Hut- 
ton's  system,  ibid.;  serpentine, 428. 

Denudation  of  decayed  rocks,  251  et 
«('(/.,  274,  277. 

Derby,  O.  A.,  geology  of  Brazil,  681. 

Descartes,  plenum  of,  57,  02. 

Detrital  rocks,  alteration  of,  108,  fi72,C8s. 

Devllle,  II.  Salnte-Claire,  dissociation,  5.1 ; 
soda-dolomite,  171 ;  artificial  produc- 
tion of  zeolites,  etc.,  156  ;  dissociation 
of  aluminous  silicates,  ilnd.;  crystalli- 
zation of  amorphnus  matters,  173. 

Devonian  age  of  Taconian,  supposed, 
031. 

Dextrose,  hydrous  and  anhydrous,  .504. 

Diagencsis,  105;  its  importance,  173. 

Diabase,  mesozoic,  121.211,  wo^',  ,338,  440. 

Dlau'onds,  .503,  .504,  Osl. 

Diaii.'ore,  377;  arlilieial  production  of, 
504. 

Dichrotte-gneiss,  412,  478,  482.  See  L> 
lite. 

Dieulefait,  serpentine,  474,  501  ;  ophites 
of  the  Pyrenees.,  502,  note ;  views  of 
T.  Sterry  Hunt  on  serpentines,  ibid. 

Dillsburg,  Pi'nn.,  iron  ores  of,  560  tt  seq. 

Diinetian  rocks,  417,  419. 

Dioritic  group  (lluroniau),  of  Kominger, 
579,  .581. 

Dipyre.  .301.  SMet  seq. 

Disintegration  of  rocks,  273,  277. 

Dissociation,  its  universal  application, 
48,  53  ;  of  b,;iicates,  148,  150,  240. 

Dislocations  of  Cambrian  strata,  639  et 
seq. 

Dolomite,  its  origin  and  formation,  171 
et  seq. 

Dolerite,  decayed,  271;  chrysolltio,  211 
et  seq.,  512;  analysci  of,  212;  mica- 
ceous banded,  211,  note. 

Dorset  Mountain,  Vt.,  031. 


1    '  t 


I 

\ 


G94 


INDEX. 


Douglas,  James,  elemental  matter,  49, 
Hole. 

l^raiiur,  J.  W.,  Arab  physicians,  10. 

J)u  tango,  GlossariuMi,  7. 

l)ucktown,  Teuu.,  metalliferous  veins  of, 
V£i. 

I>iilulh,  noritesof,  5S0. 

]>uinas,  J.  li.,  elemental  matter,  49,  56  ; 
niolucular  volumes,  302. 

Dumoiit,  geyscrian  deposits,  96. 

Duncan,  P.  M.,  interstellar  medium,  43. 

Duroeher,  J.,  two  igneous  terrestrial 
niugiuas,  207  ;  Comparative  Petralogy, 
20S  ;  ulii|uation,  208,  214  <-/  se<j.,  245  ;  sec- 
ular v:  riatioii  in  eruptive  rocks,  214 
I't  ser/. 

Dust,  ccKMnic,  its  possible  origin,  51. 

DwigUt,  W.  B.,  (Jrci'ii-Pond  Mountain, 
N.  Y.,  5'Jl ;  geology  of  eastern  New 
York,  642. 

I)yiianuos  defined,  12, 13. 

Dyiianiicist,  13. 

Dynainids,  Herzelius  on,  13. 

Dysyutribite  (pinile),  163. 

Kautii,  igneous  origin  of,  C8 ;  its  inte- 
rior, 86  it  seq. ;  regarded  as  solid,  81, 
114,  118,  201,  242  ;  congealed  from  cen- 
tre, 175  et  seq.;  chemistry  of  cooling, 
87, 117;  hypothesis  of  liquid  interior,  87, 
207. 

Eaton,  Amos,  his  pupils,  518  ;  Geological 
Text-book,  ibid. ;  Survey  of  Krie  Canal, 
ibid.:  triple  division  of  strata,  il/iil.,ry27; 
classilication  of  American  rocks,  518 
et  stq, ;  coals  of  Penn.,  521  ;  tabular 
view  of  his  system,  520  ;  his  generaliza- 
tions, 521,  526,  587.  CIO,  652. 

Ehelmen,  atmosphere,  chemistry  of,  30 
it  ni'ij.;  secular  changes  in,  34;  rock- 
deoay,  .SO,  250,  308,  50.5. 

Eichhorn,  action  of  silicates  on  dissolved 
bases,  li.'). 

Elastic  sandstone,    flee  Itncolumite. 

Elba,  serpentines  and  granites  of,  476. 

Elemental  matter,  47  et  -leq.,  52  et  seq;  in 
nebulie  and  stars,  48. 

felie  de  Heaumont,  carbonic  dioxyd,  39  ; 
the  first  granites,  81  ;  hydroplutouic 
hypothesis,  S)C  et  feq. 

Eliquation  in  rock-nia^^ses,  180,  208  et 
spf/.,  245  I  inmotalUc  alloys,  209;  com- 
pannl  withcrenltic  aetion,  217  et  seq. 

Eunuons,  Ebenezer,  geology  of  Kew 
York,  403,  621 ;  Cambrian   627 ;   ser- 


pentines, 428 ;  eruptive  limestones, 
228,  403  ;  Taconio  system,  523,  527,  534, 
588 ;  Lower  Taconic,  555  et  seq.,  572  ; 
Upper  Taconic,  583  et  seq. :  rocks  of 
Quebec,  584  ;  Taconic  slates,  ,585  et  seq., 
644  et  «(•(/.,•  Taconian,  in  Maine,  572; 
Massacluisetts,  5"4 ;  North  Carolina, 
558, 502  ;  Pennsylvania,  5.'}2  ;  Arkansas, 
676  ;  Lake  Superior,  579,  675  ;  rocks  of 
St.  Lawrence  Co.,  N.  Y.,  577;  Sparry 
Lime-rock,  585  et  seq.,  617,  643  et  acq., 
646  ;  uplifts  in  strata,  644  ;  American 
Geology,  588  ;  3Ianual  of  Geology,  563. 

Empedocles,  3. 

Endogenous  rocks  defined,  73,  154,  229 ; 
banded  structure  of,  125,  223  et  seq., 
2;32. 

Endoplutonic  liypothesis,  84,  85,  104; 
rocks,  laminated  structure  of,  200, 
205. 

Eugel,  a  new  magnesian  carbonate,  169. 

Enst.atito,  328,  503. 

Eolian  limestone  (Taconian),  631. 

Eophyton  sandstone,  542. 

Eozoic  rocks,  402, 412  ;  lands,  615  et  seq. 

Eozoiin  Canadensc,  109,  231,  412,  436,  482, 
498,  573,  575,  676. 

Epichlorite,  .'559. 

Epidote,  299,  348. 

Epigenesis,  105  ;  in  silicates,  363. 

Equivalent  volumes,  288,  291,  391  et  seq. 

Eriboli,  Scotland,  rocks  of,  670  et  seq. 

Erosion  and  rock-decay,  251  et  seq. 

Eruiitive  roeks,  72,  81,  96,  104,  107,  ,500  ; 
banded  structure  of,  81,89,  200  et  seq., 
210,  211,  note;  secular  variation  in,  214 
et  seq.;  limestones,  90, 94,  95, 228, 403, 477; 
gneisses,  81,  201  et  seq.,H)S;  iron-ores, 
95, 96, 403, 405, 429  ;  steatite,  429;  quartz, 
95,  429  ;  rock-salt,  96  ;  metalliferous 
veins,  74,  05. 

Erzgeliirge,  Saxony,  479. 

Eschwege,  geology  of  Brazil,  564. 

Esinarkite,  142. 

Ether,  cosmic,  58  et  seq. 

Eudialyte,  ,344. 

Eulytite,  :!05,  401. 

Euphotide,  299,451,491. 

Eureka,  Nevada,  Cambrian  of,  623. 

Evolution,  niinerah^gical,  688. 

Exoplutonic  hypothesis,  81,  84,  88  et  seq., 
92-iMi,  98,  101,  200,  228;  its  extravagan- 
cies, 96,  98  ;  rocks,  denied  by  Wernor, 
71,  200. 

Exotic  rocks,  73  et  seq.,22V. 


INDEX. 


695 


sruptive  limestones, 
system,  523,  527,  5M, 
inic,  555  et  seq.,  572  ; 
583  et  set]. ;  nicks  of 
)iiic  slates,  585  et  seq., 
iiiiin,  in  Miiiiie,  572  ; 
"4 ;  North  Carolina, 
vanla,  532  ;  Arkansas, 
ior,  57'J,  075  ;  rocks  of 
.,  N.  Y.,  577;  Sparry 
!  seq.,  617,  G43  et  seq., 
trata,  G44 ;  American 
luuul  of  Geology,  563. 

dettned,  73,  154,  229  ; 
3  of,  125,  223  et  seq., 

lOtUesis,   84,    85,  101; 
il    structure   of,    200, 

lesian  carbonate,  169. 

raconian),  631. 

lie.  542. 

112;  lands,  615  et  seq. 

3,  109,  231,  412,  435,  482, 


silicates,  363. 

2S8,  2'Jl,  391  etseq. 
ocUs  of,  070  tt  seq. 

lecay,  251  ef  seq, 

81,  90,  104,  107,  500  ; 
of,  81,80,  200  ef  seq., 

cular  variiitiou  in,  2l4 
,90, 04,  05,  228, 403,  4T7| 
t  seq.,  403  ;  iron-ores, 
;  steatite,  420;  quartz. 

It,  96;  metalliferous 

,',  470. 
of  Brazil,  564. 

t  seq. 


,491. 

anibrian  of,  623. 

ogical,  6S8. 

lesis,  81,84,  88  e<  seq., 
,  228;  its  extravagan- 
ks,  denied  by  Wenior, 


seq.,22d. 


Facciolatus    and  Forcellinus,  Totius 

Lutinitiilis  Lexiion,  2,  niite. 
Fahlunite,  112. 

KarnUaui,  QiielKic,  Ordovician  of,  606. 
Kar.ulay,  chomical  eliange,  15. 
Faults  in  strata,   502,  OOJ,  040,  041,  644, 

070,  671. 
Favro,  Alph.,  geology  of  the  Alps,  457, 

402,  409,  et  seq. 
Feldspars,  decay  of,  31 ;  formed  in  the 
wet  way,  120,  157,  220  ;  in  dry  w.ay,  209, 
219,  375;  analysis  of,  212;  intorniedi- 
•ite,  294  et  seq. ;  family  of,  330,  Oi-jS  ;  asso- 
ciated in  dialuise,  339. 
Ferric  oxyd,  reiiluccs  alundna,  305,  344, 

340  et  seq. 
Figline,  Italy,  seriicntinos  of,  490. 
First  liraywacko  of  Eaton  (Upj)er  Ta- 
conic),  019  et  acq.,  ri22,  52.'!,  58.'!,  008,  010, 
C28,  035,  070;   in   I'ennsylvania,  539  et 
seq.,  589  ;  in  Canada,  594  ef  seq. ;  thick- 
ness of,  580, 592,017,039;  unconformable 
to  Transition  Argillite,  526, 587, 598, 020  ; 
ajiparent  inversion  of,  592;  overlaid  by 
Second  Oraywacko,  580,  598,  027  ;  con- 
founded with  Sticond  Graywacke,  253, 
C84,  587,  594,  649,  053  ;   error  of   this 
in  American    stratigraphy,  054.     See, 
Hudson-Uivor   group,   Taconic    Slate- 
group  aii(t  (Juebec  group. 
Flunrids,  sub-order  of,  ;>0. 
Fluorhydric  acid,  action  of  on  silicates, 

214,  087. 
Fontiiine,  W.  M.,  section  in  Virginia,  550. 
Fontaincbleau  sandstone,  .104. 
Forcellinus.    See  Faceiolatus. 
Ford,  S.  W.,  Cambrian  in  eastern  New 

York,  039. 
Forchhammer,  kaolin,  360. 
Formulas,  chemical,  and  notation,  302, 

312. 
Fossil  searwaters,  253. 
Fouque  and  .^lichcl  I.(5vy,  artificial  pro- 
duction   of  crystalline    silicates,   209, 
219,  375. 
Fouque,  analysis  of  rocks  of  Santorin, 

213. 
Fournet,  rock-decay,  247. 
Frankfort  slati's,  625. 
FrapoUi,  sepiolite,  448. 
Frazor,  I'ersifor,  linionitcs,  264 ;  geology 
of  Pennsylvania,  439, 540, 590,  note ;  iron- 
ores  of  Dillsburg,  551. 
Freiesleben,  sepiolite,  448. 
Fremy,  artificial  production  of  quartz,  149. 


Frt5my  and  Fell,  artiflci.al  production  of 
connidum,  ;!(li»,  note. 

Frenirh  llroail  Kiver,  N.C.,  section  on,  559. 

Frit/.selie,  gaylussito,  171. 

Frie<lel  and  Sanasin,  aitilUial  produc- 
tion ot  quartz,  triclyniite,  feldspars, 
etc.,  157. 

Fusion,  igneo-aqueous,  90,  222,  245. 

Gaiiii,  W.  M.,  geology  of  San  Domingo, 

083,  note. 
Gabbro,  origin  of  the  name,  451;  species 
of,  il>l(t.;  rosso  and  verde,  491,492;  of 
Montul'errato,  495. 
Galen  on  lliiipoorates,  8,  note. 
Galestro,  400. 

Galenoids,  tribe  of,  378. 

Garrigou,  serpentine,  .'502,  note. 

Garnet,  340 ;  associated  with  prehnite, 
121  ;  manganesian,  of  coticulite,  425, 
note. 

Giiataldi,  IJart.,  his  geological  work,  458 
et  seq. ;  list  of  piil)lication»,  ihitl.,  note  ; 
serpentine-breccia,  453;  antiiiuity  of 
Italian  serpentines,  i'lG  ;  (.'■>->''"f!''''''' 
sections  by,  459  ;  his  two  groups  of 
crystalline  roeks,  4()0  et  seq. ;  studies 
in  tins  liiellesi!,4G2  ;  older  and  younger 
gneisses,  4(i4 ;  pietre  verdi,  403  ;  its 
thickness,  405;  granitic  rocks  and  por- 
phyries, 471 ;  geology  of  the  Alps  and 
Apennines,  483. 

Gastaldite,  310  ;  relation  of  to  jadeite, 
348. 

Gamliii,  fused  alumina,  300,  note. 

Gaylussito,  formation  of,  171. 

Geikie,  Alex.,  rock-decay,  271  ;  crystal- 
line schists  of  Scotl.ind,  009, 671 ;  meta- 
mori)liisni,  072. 

Geikie,  .Jas.,  serpentines,  510. 

Gems,  order  of,  281,  315. 

Gen(.'tic  history  of  crystalline  rocks.  See 
190  et  seq. 

Genth,  F.  A.,  metasomatism,  100,  102; 
pseudoniorphisni,  101  ;  diilienon,  ibid. 

Genoa,  serpentines  of,  452,  485.. 

Geodiferous  I,ime-rock  of  Katon,  627. 

Geogeny  detlned,  28. 

Geognn.-y  detlned,  27. 

Geological  map  of  New  York,  O.^O  :  sur- 
vey of  New  York,  521  et  seq. ;  Railroad 
Guitle,  .T.  Macfarlane's,  601,  007  ;  Text- 
book, Katon's,  518. 

Geometrical  chemistry  of  II.  Wurtz, 
395. 


I 

1 1 


!  a 


696 


INDEX. 


twi* 


Georgia,  State  of,  Taconian  in,  6C3 ;  de- 
cayed gueiiis  in,  258  ;  Stone  Mountain 
in,  258,  274,  note. 

Georgitt,  Vermont,  slates  of,  RM. 

Geui'giuu,  proiioseil  division  of  Cambrian, 
528. 

Gerliardt,  Ch.,  lioniologous  or  progres- 
sive series,  289 ;  atomic  volumes  of 
native  oxyds,  376  et  seq. 

Gerlacli,  geological  sections  in  Italy,  468 
et  seq.,  473. 

Geyserian  deposits,  96. 

Gibbs,  Wolcott,  complex  inorganic  acids, 
387  et  seq. ;  and  Genth  on  cobalt-ammo- 
nias, 386. 

Glan,  P.,  interstellar  ether,  64, 

Glauvil,  Scepsis  Scieiitilica,  5. 

Gl.icial  drift,  origin  of,  251  et  seq. 

Glaciation,  J.  F.  Campbell  on,  46. 

GlauzscUief er  of  the  Alps,  464, 467  et  seq., 
473,  683. 

Glass,  decomposition  of  by  hot  water, 
147. 

Glauoonite,  history  of,  196  et  seq, ;  analy- 
ses of,  198  ;  origin  of,  309,  333. 

Glaucophane,  310. 

Glinkite,  509. 

Gneiss,  Werner  on,  74 ;  Hutton  on,  75  ; 
eruptive,  81, 201  et  scg.,  403;  aqueous,  82, 
131:  from  limestone,  102  el  seq.;  rela- 
tion of  to  granitic  veins,  124,  125,  236, 
241,  243  ;  older,  of  Xorth  America,  107, 
404,  412,  665  ;  younger  of  do.,  406,  423, 
437,442,4806/  seq. ;  older,  or  central,  of 
Alps,  459, 462, 465, 472, 481, 683 ;  younger, 
or  recent,  of,  46".,  404,  466, 471,  472,  482 ; 
apparent  unconformity  of  faese,  463, 
469,  481 ;  Gastiildi  on  the  two  gneisses, 
464 ;  Bojian  and  llorcynian,  481 ;  Lew- 
Isian.  417. 

Goessmann,  C.  A.,  dolomites  of  Syracuse, 
446. 

Goroeix,  geology  of  Brazil,  680, 

Gosselet,  rocks  of  the  Ardennes,  421. 

Gower,  7,  vote  ;  delinition  of  physic,  2. 

Graham,  Thos.,  colloids,  19 ;  pectlsation, 
315,  322,  323,  note. 

Grampian  rocks,  423,  670. 

Grand  Caflon  group,  614,  624. 

Granite,  Werner,  Saussure,  and  Hutton 
on,  72;  Beroldingenon,  82;  the  primitive 
substratum,  80  et  seq.  eruptive,  90  et 
seq.,  204 ;  derived  from  limestone,  102 
et  seq. ;  aqueous  origin  of,  116, 131, 177 
et  seq.,  204,  242;    water  in,  96,  217; 


banded  structure  in,  211,  no/e  ,•  of  Alps, 
471 ;  of  Klba  and  Corsica,  475, 

Granitic  aura,  128  ;  "juice,"  127;  vein- 
stones, 72, 123e<  seq.,  125;  in  various 
localities,  223,  226  ct  seq.,  657,666;  in 
serpentine,  438  ;  in  basic  rocks,  122, 137  ; 
genesis  of  minerals  in,  309. 

Granitone,  451. 

Granulitc,  411,  439;  of  Saxony,  202,478. 

Graptolitic  shales  of  Levis,  595,  608,  625 
647  ;  of  Teach  Bottom,  I'enn.,  690. 

Gras,  Soipion,  on  serpentine,  428,  432, 
note. 

Graves  Mountain,  Georgia,  563. 

Graphite  in  Laurentian,  1U9 ;  In  Taco- 
nian, 561,  573,  580,  682. 

Gray  Sandstone  of  Knimons,  522,  524. 

Granular  Quartz-rock  of  Eaton.  Sec 
Primitive  Quartz-rock. 

Granular  Lime-rock  of  Katon.  See  Primi- 
tive Lime-rock. 

Graywacke.  See  First  Graywacke  anil 
Second  Graywacke. 

Greenstone  (lluronian)  seriis,  404,  406, 
411 ;  group  of  Lake  Superior,  404,  611 ; 
of  Cornwall,  Eng.,  450.  See  liurouion 
and  Pietre  verdi. 

Green  Mountains,  408,  400,  410,  594,  635 ; 
serpentines  of,  429, 436 ;  their  pre-Oam- 
brian  age,  619,  620. 

Greeu-Pond  Mountain,  590,  591,  632,  637. 

Grenvillo  series,  412,  413,425. 

Groton,  Conn.,  banded  granites  of,  211. 

Grove,  W.,  interstellar  ether,  62. 

Oaillemin,  on  pholerite,  367,  .'168. 

GUmbel,  geology  of  Bavaria,  481  et  seq., 
684. 

Gypsum  with  serpentine,  4*4,  448,  467  et 
seq.  ;  in  Onondaga  group,  440  ;  in  Cal- 
ciferous  Sand-rock,  618. 

IlAciii':,  Arnold,  Cambrian  in  Nevada, 

623. 

Ilaidinger,  W.,  pseudomorphism,  83 ;  dol- 
omite, 172;  nietasonmtosis,  200 ;  trans- 
lator of  Mobs,  280. 

Hall,  James,  on  limestones  at  Port  Henry, 
Kew  York,  2.'!8  ;  supposed  Huronian  in 
Wisconsin,  54i> ;  position  of  Sparry 
Lime-rock,  587,  608;  Hudson-Kiver 
group,  601  ef  ,ieq. 

Halley,  the  earth's  interior-,  86,  note. 

Halletlinta  rocks,  409  et  seq.,  418, 515,  note, 
546 ;  unconformable  to  gneiss,  479.  Sea 
Arvunian. 


ETDEX. 


697 


:st  Graywacke  and 


inbriaii  in  Nevada, 

jmorphlsm,  83 ;  dol- 
inatosis,  200 ;  trans- 
ones  at  Port  Henry, 
poseil  Iluronlan  in 
losition  of  Sparry 
m ;    Iludson-Rlver 

tcrior,  86,  note. 
«.iei7.,418,5ir),»io^e, 
3  to  gneiss,  479.  .Sec 


Halloyslto,  ir>2,  372. 
HalKiy,  d'Oniallus  d*.    Sec  Omallus  d'. 
Huluidutuo,  Older  of,  380. 
Ilanitditi!,  a  iiiitivo  silicato,  104,  334. 
llardnoss,  riMaiinii  of  to  cUoiiiical  con- 
densation, 2W,  '^Ki,  ;i(l4,  305. 
Ilarkiiuss,  geolotsy  of  Wiili'S,  410. 
llartl,  C.  F.,  rock-ducay,  1!4»< ;  Cambrian 

in  Niiw  Uruiiswick,  407,  023. 
Harrington,    II,    J.,    ndncral    volns    in 

»Iount  Itoyal,  137  ;  aimtite,  232,  230. 
Hastings  series  of  roeks,  414,  574  et  acq., 

675. 
Hauer,  F,  von,  geology  of  Kastern  Alps, 

458e^sefy.,4G5,  471;  two  gnoissic  series, 

405,  J81. 
Hawi'S,  (J.  W.,  feldspars,  339;  veneritc, 

358,  note. 
Hdboit,  crystallino  rocks,  85;  liis  plu- 

tonic  views,  430. 
Hebrides,  gneiss  of,  417. 
Heddle,  analysis  of  pllolito,  .300. 
Hegel,  clieniisni,  15,  307. 
Hehnliollz,  clieniieal  eliaiigc,  15. 
llelderberg  limestones,  521,  G0,'»,  032. 
Heniatili!  in  aniygdaloids,  etc.,  138;  in 

dolcmitu  of  Syracuse,  415  ;  inXaconian, 

530;  brown  (.scr-  I.inionile). 
Hercyniaii  gneiss,  4!sl  ;    prindlivo  clay- 
slate,  iliUL,  084. 
Hicks,  IT.,  geology  of  Wales,  410,  418  ;  of 

Scottish  Higlilands.  009(7  sciy.;  Tebidi- 

au,  417,  422  ;  Candjriiin,  528. 
Highlands  of  the  Hudson,  403,  405,  655  et 

acq.,  658,  600 ;   are  pre-Canibrian,  666 

et  acq. 
High  liock,  apatite-niino  of,  £26. 
Hildebrand  and  Cross,  zeolites  of  Colo- 
rado, 1.35. 
Hinrichs,  G.,  elmnontal  ni.atter,  49. 
Hippocrates,    nature,   8;    medicine,  9; 

Galen  on,  8,  note. 
Hitchcock,  Edward,  on  serpentine,  428 ; 

geology  of  Verninnt,  031. 
Hitchcock,  C.  H.,  crystalline  rocks,  94  ; 

Hiironiiin,  410  ;  Taconian,  031. 
Hobokeii,  N.  ,T.,  serpentines  of,  439,  441. 
Hidxheiid,  Wales,  geology  of,  410. 
Hcdlando.  geology  of  Corsica,  473. 
Homologous  series,  2HG,  289,  394. 
Homologies  in  niineral  species,  289,  290, 

291,304,  387  ('«,sr7.,  390. 
Hoosac  Mountain,  Mass.,  decay  i!  rocks 

in,  256;  tunnel  in,  ihiil. 
Hopkins,  W.,  tho  earth's  interior,  115. 


Hornblende,  Its  decay,  32.  See  Amphi- 
bolo. 

Hot  springs,  zeolites,  etc.,  formed  in,  150 
et  aeq. 

Hot  water,  action  of,  on  glas«!,  147  ;  on 
bricks,  1,52 ;  on  feldspars,  pyroxene, 
etc.,  148  ;  on  locks,  022. 

Houghton,  !>.,  Taconi'in  of  Lako  Supe- 
rior, 579.  075. 

Hudson  slates  of  Mather,  .523,  ,'■.24. 

Hudson-Hiver  groupof  \'aiuixem,  ,524  et 
»('7.,531,  007  t-<  st-r/.;  its  two  divisions, 
524,002;  dames  Hall  on,  5s7,  001,  008  ; 
Logan  on,00K,034,  (i40  ;  farther  defined, 
038,  04(1,  070  ;  altered,  400,  4(19. 

Hughes,  1).  T.,  auriferous  gravels,  273. 

Hughes,  T.  McK.,  ge(.logy  of  Wales,  417. 

Humboldt,  A.,  the  unity  <.•"  nature,  22; 
physiography,  iliid.;  interstellar  medi- 
um, 03 ;  origin  of  nebula'  0.j  ;  serpen- 
tine, 427. 

Hummel,  congloinerates  in  Sweden,  479. 

Hunt,  K.  1?.,  terrestrial  atmosphere,  44. 

Hunt,  T.  Sterry,  Siemens  on  his  studies 
of  Newton,  51  ;  views  on  limonites 
noticed,  205 ;  views  on  serpentine 
defended,  502,  503,  note;  address  at 
Priestley's  grave,  .'■)5  et  !<e</.,  390. 

Huronian, 404, 411,430, rM :  Higsby  on,407; 
Murray  on.Osl ;  Credner,  Kimball, and 
Brookson,  ilihl. :  conglomeratesof,  254, 
411;  Serpentines  of,  430  ;  thickness  of, 
410,  .581  ;  of  Lake  Superior,  579,  Oil ;  of 
Michigan,  ,581  ;  of  New  Kiigland,  408, 
410 ;  of  l'eniisylviiiii;i,  545,  547  ;  of 
Wales,  410  ;  of  Scotland  and  Ireland, 
423  ;  of  Alps,  472  (nee  alun  Pietre  verdi) ; 
Huronian  and  Taconiiin  confounded, 
500,  581,  014;  ami  ICeweenian  con- 
founded by  Logan  and  others,  612. 

Hutton,  theory  of  the  earth,  69,  75 ; 
Naumann  on,  75;  Ilaubree  on,  76; 
granite,  72 ;  basalt,  74  ;  metalliferous 
veins,  ihid.;  Playfair's  Biography  of, 
80,  note. 

Huttonian  school,  191,  655,  668 ;  its  de- 
fects, 200. 

Huxley,  T.  H.,  matter,  18, note;  physiog- 
raphy, 22. 

Hyalite,  1.38. 

Ilydrocarlionaoeons  species,  380, 

Hydrosp.atlioid  type,  31.5,  317. 

Hydroxyspathoids,  sub-order  of,  876. 

Hydrodolomite,  170. 

Hydrous  iolitcs,  142. 


698 


INDEX. 


■ 

M^H 

i9 

9 

Hyilroplntonic  agency  In  rocks,  87,  90  et 
sir/.,  1!()1,  2\r,,  'iil,  yi!0,  222,  242,  2i6,note, 
'Mi,  4HH,  4!i2,  5(10. 

Uyuroiiliilitc,  1(U,  nnte. 

lIylo|^i'iiy  <lc'tlnt'(l,  23. 

Hyli)/()i8ni,  2(!,  note, 

llyiiogoiio  nickH  of  I-yi'll,  83. 

Ilypozoltf  rocks  of  lioncrs,  405,  M4. 

Hyi)oiihtliaiiitis,  488,  VM). 

]Iyi)ot)ie.sls,  Newton's,  touelilng  Light 
anil  (;olor,  5t,  58, 

llytiotUescs  in  science,  Stalloon,  079,  note. 

Ice,  volunu)  of,  3!i5, 

Ideal  clieniistry,  liroille  on,  54, 

Iduntiflcation  in  clieniistry,  15,  397, 

Jgneo-aiiueous' fusion,  DO,  222,  245.  See 
llytlt'oplutunlc. 

Igneous,  as  related  to  aqueous  action, !  S8 ; 
rock  (st'c  Kruptivo  rocks,  Kndoplutouio, 
Exoplutonic,  (inil  Volcanic). 

Iniiienetrability  of  matter,  397. 

Indigenous  rocks  dctincd,  72, 

Indianaitu,  an  ai'^^illoid,  372. 

India,  gef)logy  of,  iMi,  080. 

Individuation  in  matter,  13,  088. 

Inorganic  acids,  complex,  of  Ulbbs,  387 
et  scq. 

Inter/ienetration  in  clu'inlstry,  15. 

Intersi'Olar  medium,  its  supposed  con- 
stitution, 1 1,  50,  51,  (1(J ;  Newton  on,  57 
et  s(7/.,  (11  ;  its  relation  to  wiu'lds,  59  ; 
Siemens  on,  51  ;  (iiovc,  Humboldt, 
Arago,  WillianiB,  and  Thomson  on,  02 
et  seq.;  Zollner  on,  04;  supposed 
density  of,  03,  Gl. 

Intermediate  mineral  species,  29^et  se^., 
304,  338,  342. 

Intruded  solid  rocks,  204,  513. 

Inversion,  apparent,  of  Htrata,  592,  007. 

lodids.  sub-order  of,  380. 

lolite,  142,  338,  .351.     See  Dichroite. 

Ionian  physiologists,  4. 

Iron,  its  relation  to  atmospheric  oxygen, 
33;  solution  and  deposition  of,  198  ;  car- 
bonate, its  solubility,  2()e,?io/c,-  replace- 
ment of  linie-earbonate  by,  ibid, ;  oxyd, 
its  associations,  isi,  230. 

Iron-ores,  formation  of  linionites,  261  ct 
seq. ;  genesis  of  from  carbonate  and, 
BUlphid,  202  I  concretion  of,  200,  208 ; 
fossil  ores,  207  ;  ores  of  Taconian  rocks, 
636 ;  Pennsylvania,  ,550  et  seq. ;  St.  Law- 
rence (Jo.,  N.  Y.,  570. 

Iron-ore  group  uf  Romlnger,  S80. 


Iron  Manufacture's  Guide,  Lesley's,  BBC 

Iron  Mountain,  Missouri,  209. 

Irving, U.,  rock-decay,  270;  kaolin,  ibid.; 

petrosilex,    540;    Ihironian,   579,    581; 

protruding  rocks,  483. 
Isomerism    in    silicates,  ,3;i0.     See  Poly- 

merlsin. 
Issel    anil    Mazziioli,    serpentines,    487 ; 

amphimorplile  rocks,  ibid. 
Itacolnmltc-rock,  ,504,  080. 
Itacolumitic,  series  of   l.ieber,   414,  665, 

570;    history  In   S<iutli  Carolina,  507 ; 

section  of,  5(;t);  North  Carolina,  501,509  j 

characters   resumed,  074 ;   lirazil,  564, 

080;  West  Indies,  Uussia,  and  llindo- 

Stan  080  et  .leq. 
Itabirlte,  hematitio  schist,  5C0,  508,  080. 
l:aly,  geology  of,   450-478,  483-490,  514, 

083,084.    See,<ils(i,  Ga.<taldi,  Gneisses, 

I'ietro     verdi.    Serpentine,     Lustrous 

schists  (ind  Ulauzsch^efer. 
Ittnerito,  342. 

Jackson,  C.  T.,  crystalline  rocks,  059. 

Jackson,  K.  S.  M.,  linionltcs,  264. 

JadiMte,  301,  ,348. 

Jamaica,  geology  of,  083. 

Jameson,  Itobert,  serpentine,  427  ;  natu- 
ral-history method  of  mineralogy,  280. 

Jamicson's  Scottish  Dictionary,  10,  note. 

Jervis,  1  Tesori  Sotteranei  del'  Italia, 
477  ;  rocks  of  Italy,  iVj/(/.,084. 

Johnsiin,  S.  \V.,  and  lilake,  J.  M.,  kaollD, 
308. 

Jollyte,  143,  301. 

Jones  Jlino,  Penn.,  357,  note,  651. 

Judd,  J.  W.,  rocks  of  IJotzen,  515,  note; 
the  Scottish  Highlands,  671. 

Julien,  metasomatism,  100;  pseudomor- 
phism, 102. 

Kant,  chemical  change,  15. 

Kaolin,  formation  and  density,  31 ;  re- 
tains alkalies,  127, 161,  2,54;  occurrence 
in  Connecticut,  24U ;  from  Taconian 
slates,  549,  550  ;  from  beryl,  370;  from 
scapolite,  371. 

Kaolinite,  367,  309. 

Karstenite  in  crystalline  schists,  41S, 
448,  408. 

Keilliauite,  345. 

Keramlte,  an  argilloid,  371. 

Kerr,  W.  C,  frost-drift,  275,  note;  geology 
of  North  Carolina,  558 e<  seq.;  Taconian 
In,  560  et  seq. 


IJJDEX. 


099 


schist,  506,  5G»,  C80, 
m-i1X,  4^3-190,   .114, 
,  UiwtdUli.Giiuisses, 
jrpuiitiue,     Lustrous 


,  f.83. 

eriieiitiiio,  427 ;  nntli- 

|l  of  mineralogy,  280. 

Dlcliimiiry,  10,  Jio^t'. 
)tteriinei  del'  Italia, 

,  ;/)((/.,  084. 

Blake,  J.  H.,  kaolin, 


357,  note,  651. 

of  l?()t7.en,  515,  no<e; 

lands,  671. 

sm,  lOOj  pseudomor- 


vnge,  15. 

luid  density,  31 ;  ro- 
,  Uil,  2r)4;  oecurrenco 
iV.i;  from  Tacoiiian 
oni  beryl,  370;  from 


itallino    schists,  416, 


Did,  371. 

ift,  275,  no^e;  geology 
558  ««««/., -Taoonian 


Kcwppninn  sorlos,  415,  B2S,  BTS,  BSD,  625  ; 
luimo  of,  415,  014  ;  lii8t.>ry  of,  611 ;  sup- 
posed organisms  of,  015  ;  probably  pre- 
Cambrlan,  021,  025;  congb>morati'H  in, 
254,  415,  OU;  coutoundfd  by  some 
with  Huroniiui,  612. 

Keweenaw  and  Kcweoiiawlan,  415,  614. 

Kimb.iU,  J.  P.,  Laureutian,  405 ;  lluro- 
niau,  681. 

Kinetics,  12. 

King,  Clarence,  crystalline  rocks,  02 ; 
volcanic  agency,  ibid. 

King  and  Itowuey,  metasomatism,  90, 
497  et  acq. 

King's  Mountain,  S.  C,  rocks  of,  559,  561, 
604  ;  Lieber  on,  500  et  seq. 

Kingston  series,  408. 

Kishacoquillas  Valley,  geology  of,  530  et 
seq.,  540. 

Klttatinny  Mountain,  Tenn.,  rocks  of,  531 
ct  seq.,  538,  510  ;  uncouformity  to  argil- 
lites,  632,  540. 

Kittell,  inclined  crystalline  strata,  111. 

Kjorulf,  geology  of  Norway,  508,  685. 

Klopstock,  nature,  23,  itnte. 

Koenig,  astrophylliti',  355. 

Kopp,  A.,  crystalline  rocks,  93. 

Krablite,  a  supposed  feldspar,  294,  338, 
340. 

Kuhlmann,  F.,  water-glass,  149. 

Kunz,  G.  F.,  orthoclase  veius  in  diabase, 
121. 

Kyauite,  101,  300,  503. 

LADRADOiti.VN,  413.    See  Norian. 

Labradorite,  338,  371 ;  rocks,  404,  413, 580. 

Lako  St.  John,  Ordovician  of,  599. 

Lake  Sui)erior,  geology  of,  205,  578  et 
seq.,  010  (t  seq, 

Lamination  in  rocks,  from  movement: 
exoplutonic  view,  81,  201  et  seg,,  210  ; 
endoplutonic  view,  200,  205. 

Lambertville,  K.  J.,  banded  diabase  of, 
211,  note, 

Lapie-lazuli,342. 

Lapworlh,  C,  Ordovician,  528;  Scottish 
Highlands,  070. 

Laumontito,  veins  of,  l."5. 

Laurent,  Aug.,  water  in  fused  borates, 
220;  constitution  of  silicates,  297;  di- 
visibility of  molecules,  (//((/. 

Laurentian  series,  404,  412,  COO  :  its  divis- 
ions, 413 ;  limestones,  109,  220,  238,  4.35, 
658  et  seq.,  CGO;;  serpentines,  109,  332, 
435 ;  in  the  Adiroudacks,  403  ;   south- 


eastern New  York,  403,  405,  650  et  seq., 
658,  ClO,  665  et  seq.;  South  Mountain, 
I'enn.,  257,  549;  Buck  Uidge,  renn., 
437,  550  ;  North  Carolina,  500 ;  Colorado, 
223  ;  Canada,  223  et  seq.,  403  et  seq.,  412  ; 
Alps,  402,  472,  479;  Ilavaria,  482.  ice 
Gneiss,  older,  of  Alps. 

Laun'Mtidi'S,  404  ;  not  the  nucleus  of  the 
continent,  500. 

I.au7.on  rocks,  506,  6.34. 

l.avas,  water  in,  06  el  seq.,  222, 245,  note. 

Lavoisier,  eloniental  nuittor,  49,  57. 

Lazulile,  BG'S. 

Lead,  iiialato  of,  its  cry3talliz,ation,  170. 

Leboiir,  on  Carrara  marbles,  477,  noti. 

LeCoute,  ,Ios.,  gold  gravels  of  C.difornl.l, 
272. 

Lehman,  on  prindtive  rocks,  68  et  seq. 

Leliinann,  .Job.,  lamiuiitcil  rocks,  202. 

Leibnitz,  primeval  eartli,  ri8,  70. 

Le  lloyerand  Dumas,  mulecidar  volumes, 
302. 

Lesley,  J.  P.,  limonltes  in  Pennsylvania, 
203  et  neq.;  iron-ores  in  do.,  5.50  ;  iron 
Manufacturer's  (inide,  ilnil.;  Potsdam 
sandstone,  600,  iin/e ;  relations  of  tho 
Second  (iraywaeke,  632,  nnle ;  on  H. 
I).  Kogers,  658. 

Leucite,  artificial  production,  219 ;  change 
to  analcite,  371. 

Levant  Siimlstone,  5,^4. 

Levis  limest  -no,  608,  047.  Sec  Sparry 
Limc-roek. 

Lewisian  gneiss,  417. 

Lewis,  11.  C,  laminated  rocks,  203;  ter- 
tiary 'imonites,  i;63,  note. 

Lherzoiite  rocks,  500  ;  in  North  Carolina, 
507  ;  Norway,  Pyrenees,  and  elsewhere, 
608  ;  their  stratified  character,  iOitl,  See 
Chrysolite. 

Lieber,  Oscar,  serpentine  and  steatite,  429 ; 
Itacolumite  rocks,  ,"65  et  .feq.,  680. 

Liguria,  serpentines  of,  452,  485  et  seq,, 
405  et  seq. 

Lime-carbonate,  origin  of,  178,  239,  2.53 ; 
solubility  of,  108  ;  replacement  by  iron- 
carbonate,  266. 
Limestone,  decay  of,  249,  271 ;  with  ser- 
pentines, 4.'!5,  462,  501,  573;  si^)posed 
metasomatic  changes  of,  102  ;  changed 
to  granite  and  gneiss,  103,  408;  of 
Clielmsfoni,  Mass.,  230;  St.  John, 
N.  B.,  ,572;  Kockland,  Me.,  iliid.;  Port 
Henry,  N.  Y.,  237  ;  of  Stockbridge  {see 
Stockbridge   limestone) ;    Auroral  (see 


I  I 


# 


111  . 

•1: 


700 


INDEX. 


Auroral  Hmostone) ;  eruptive (weEnip- 
tlve  rocks). 

liiiuoniios,  tertiary,  203,  notf ;  Taconlan, 
I'd,  Ii.'i.'),  5:Wi,  5,">5;  not  from  inaiinetito 
nor  lu'iiiatitc,  601) ;  from  Bitlorltu,  atjl, 
4H1,  07.1,  nso  ;  pyrites,  lifi!»,  L'Cl,  no",  r,m  ; 
Bcrpnntiiie,  2f3M  ;  contiaotion  in  forma- 
tion of,  lliiL' ;  hollow  I,  assoH  uf,  ihid. ; 
of  Appalaclii.iu  Valley,  1:01,  1!C4  ;  Stati'u 
Islanil.aW  ;  .South  Carolina,  509  ;  Nova 
Scot.ia,  .573  ;  ^Aliohigaii,  5S0  ;  oonnlomer- 
ntos  of,  fi"). 

T'iugula  of  Auroral  limestone,  582. 

hinmeus,  orystallino  ruclis,  O'J. 

IJiMKMiiaiin,  zircon,  l!!4,  noti'. 

Ijinvlllc  Mountains,  X.  C,  053,  550. 

Littrc,  Dictiiiiiary,  7,  8. 

l.lanlicris,  Wales,  slati^s  «♦,  420. 

Llano  ffroup  of  Texas,  021,  024. 

Llyn  Padarn,  WaloP,  coiigloniurates  of, 
420. 

Locke,  John,  natural  p.illosophy,  3. 

Lockyer,  .J.  X.,  cosmic  evolution,  48; 
solar  physit"),  r>X 

Logan,  \V.  K.,  I.aiirontlan,  2.1R  ;  Potsdam 
group,  O0!t,  Oil,  Oi:i,  670  ;  Hed  Sand-rock 
of  Vermont,  008 ;  (,»neboc  group,  507 
603,  031,  070  ;  altered  Quebec  (jroup,  40C, 
410,  610  ;  altered  IIiidson-Kiver  (.'rouft, 
400,  409  ;  geology  of  Hu<lson  Valley, 
603,  640  (•/  seq.;  Tnconian.  603,  634; 
Keweenian  as  Hnronian,  012  ;  as  Que- 
bec group,  41.1,  610,  013 ;  great  fault 
imagined  by,  6(12,  640. 

Loraine  shales,  .520,  ,522,  .524  ct  sea.,  537. 

Lory,  geology  of  the  Alps,  400  et  seq. 

Lotti,  seriieiifnes,  474,  .502. 

Lower  Taconic.    See.  Taconian. 

Lustrous  schists  of  the  .Alps,  464,  407, 
473,  0S.3.    See  Olanzschiefer. 

Lyell,  Ch.,  hypngene  rocks,  83 ;  rock- 
decay,  248. 

Lyman,  B.  S.,  llmonites,  265. 

Lyncurite,  a  zircon,  307. 

MArrri,T.orii,  J.,  Geological  Classifica- 
tion of  Kocks,  427  ;  serpentines,  ibid. 

Macfarlane,  Jas.,  Geological  Railroad 
Guide,  601,  607. 

Macfarlane,  Thns.,  primary  rocks,  86 ; 
endoplutonic  hypothesis,  87,  205  ;  crys- 
talline rocks,  ihid.,  406,  663 ;  Kewee- 
nian conglomerates,  614 ;  Hastings 
series,  67.5. 

Macigno,  eocene  sandstone,  473,  486. 


Mackintosh,  J.  B.,  itudles  of  native  vill- 
cates,  087. 

Maelure,  W.,  American  geology, 403, 673  ; 
his  Transition  series,  ,5.57  vt  acq. 

Macvib  .Mountains,  N.  Y.,403. 

Magu.as,  interior  igneous,  87,  129,  207, 
212. 

Magnesia,  sources  of,  170,  2.39  ;  in  noo- 
water.  182 ;  carbonates  of,  169,  170, 
iX\;  native  silicates  if.  325;  their  geu- 
CH  8,  170,  177,  133,  448,  499,  502,  612. 

Mag.iesian  slates  of  Emmons,  584,  585, 
643  et  seq. 

Magnetite,  in  amygdaloid,  etc.,  138 ;  in 
granitic  veins,  223  ;  production  of,  148, 
181,  2(li»,  220  ;  in  Pennsylv.uiia,  536.  660, 
et  seq.,  6.53,  570  ;  cobalt  in,  530,  653,600. 

Maine,  Taconian  in,  572. 

INIalate  of  lead,  crystallization  of,  170. 

Mulacone,  300,  307. 

Malvern  Hills,  Eng.,  geology  of,  421. 

Mangane.sc,  1.39,  201,  ,5;iO  ;  carhon.ate  of, 
ihi(l.,note ;  sesquioxyd  in  silicates,  348, 
350  ;  in  Laurentian  veinstones,  231. 

Manhattan  Island,  N.V..  geology  of, 656, 
603,  000  ;  serpentiiu'S  of,  4.39. 

rdanual  of  Geology,  Kmnions,  563. 

Marblehead,  Mass.,  conglomerates  of, 
420. 

Marbles  of  Taconian,  554.    See  Taconian. 

Marialito,  ,341. 

Marquette,  Mich.,  geology  of,  579,  581. 

Marco\i,  .1.,  Taconian,  518,  636. 

Marr,  crystalline  rocks,  93. 

Marmora,  De  la.  geology  of  Sardinia,  476. 

Massa,  Italy,  marbles  of,  473. 

Matinal  rocks  of  Kogers,  ,5.33,  538,  639. 
Sei  Taconian,  First  Graywacko  and 
Second  Graywacke. 

Mather,  W.  W.,  geology  of  New  York, 
523  ;  Hudson  slates,  i6/'r/.,524  ;  Hudson- 
Kiver  group, ,507;  First  Graywacke,  523, 
583,  584,  653  ;  Taei.ilc  system,  628  ;  ser- 
pentines, 441,  659;  geological  map  of 
New  York,  659;  crystalline  rocks,  403, 
405,  608,  6,52,  055  et  seq.,  659;  his  hy- 
pothesis as  to  American  stratigraphy, 
651,6.55,  657  ('<.<»C(7. 

Matthew,  G.  F.,  geology  of  New  Bruns- 
wick, 407,  408. 

Matter,  Bacon  on,  20,  nnte ;  Schelling  on, 
21,  7iote.  23,  7wfe;  elemental  or  pri- 
mary, 13,  49,  56  et  seq. 

Mazzuoli  and  Issel,  serpcutines,  etc.,  486, 
487.  ,         . 


'4K- 


INDEX. 


701 


diei  of  natiTe  alll- 


lization  of,  170. 


154.    Sue  Taconlan. 


»y  of  Now  Bruns- 


[jcutines,  etc.,  486, 


Medlrlnor,  10 ;  Iti  etymology,  ibid.,  note, 

Medlc.'iHtur,  10. 

Muilioliii',  llippocrates  on,  8,  9. 

Mi'iliiiu  Hiiiulstone,  5JL'. 

Mulilltu,  Ui4,  [r,r>. 

MuinphreiuiigdB  Litkc,litnc8toiin!i  of,  031, 

Menage.  I>ictiunuaire  Ktyinnloglque,  7. 

Meneglilnl,  geology  of  the  Alps,  473. 

Mental  pliysiokigy,  6, 

Menevliin  rocks,  407,  573,  677,  018,  G'.'S. 

JSIeuoiuinoo  UlBtrict,  Mich.,  geology  of, 

blH,  6«0,  075. 
Mesozoii!  in  I'onn.,  W5,  549. 
MetageneHls,  14. 
Molallates,  oriler  of,  3;;o,  378  ;  volumes  of, 

;i79  et  siq. 
Metallic  all.. 72,  en.iimtiDii  in,  209. 
Metalliferous  I  line-rock  of  Katon,  520, 

521  i   veins,  igneous  origlu  of,  74,  00. 

See  Veinstones, 
Metallometallates,  sub-ortler  of,  o78. 
MotuUoids,  tribe  of,  378. 

Metamorphosis,  hypothesis  of,  'r,,  00,  P2, 
104,  107,  403,  0.14  et  mi/.,  Cis,  C8K  ;  T?onU 
and  Lyell  on,  82,  83:  Delesso  0)i,  4;i2; 
Mather  on,  629,  O.W  ff  mq.;  falla- 
wayand  Honnoy  on,  008;  Dana, . I.  I)., 
on  grades  in,  005,  07H  ;  rise  and  fall  of, 
108,008;  inechaidca!,  20.'),  072;  in  New 
England  and  New  York,  055  et  seq.i 
Scottish  Highlands,  009  et  seq,;  de- 
fined as  pseudomorphism  on  a  broad 
scale,  100,  200. 

Metasoniatosis,  hypothesis  of,  84, 105.  497 
et  seq.;  its  difflrulties,  108;  two  schools 
of,  98  et  seq.,  101 ;  of  pUUonic  rocks,  99 
et  seq.;  of  limestones,  102  et  seq.'; 
Haidlnger  and  Rischof  on,  200 ;  Pum- 

.  pellyon,498;  Dana,  J.  I).,on,  101,7m?e,' 
of  granite  to  limestone,  101,  7io^',  498  ; 
limestone  to  granite,  102  et  seq.,  498 ; 
serpentine,  to  limestone,  498 ;  grfvnite 
to  serpen'Jne,  431  ;  limestone  to  ser- 
pentine, 102  ;  limestone  to  petrosilex, 
103,  498;  limestone  to  hematite,  103, 
499 ;  corundum,  100  ;  chrysolite,  101. 

Methylosis,  498. 

Meunier,  Stanislas,  sources  of  carbonic 
dioxyd,40;  planetary  atmospheres,  ibid. 

Micas,  353,  3.'56, 308  ;  artificial  production 
of,  149  ;  origin  of,  160  ;  table  of  musco- 
vitic,  ibid. 

Mica-schist  (Montalbani  series,  411,  413, 
423,  403,  460,  472,  479  et  seq.,  482;  of 
Michigan,  580  et  seq. ;  New  York  city, 


606  et  seq. ;  Alps,  401,  CS.T  ;  Saxony,  202, 
47H  ;  liavaria,  4H1,  .Ij'ic  tiuuiss,  younger, 
and  .Montalbau. 

Michel  Levy  a;id  Fou(|Ui*,  formation  of 
■lllcatOH,  209,  219,  375. 

Michigan,  geology  of,  579  ct  seq.,  075. 

Mimetic  resemblances  in  minerals,  108, 
31H. 

Blinas  Geraes,  Brazil,  geology  of,  604, 
080. 

Minnesota,  rock-decay  in,  270  ;  geology 
of,  579  et  seq. 

Mincralogical  evolution,  088. 

.Mineralogy  dellned,  2.'>;  basis  of  classlfi' 
cation  in,  lt;5,  107;  scope  of,  287,398; 
natural-history  ni,,i;-od  In,  2>^0,  2H3  j 
cliemical  method  in,  2m2  ;  natural  sys' 
torn  of,  279,  2M7,  297  ;  history  of  its 
develnpmenl,  2Hl  et  neq.;  Objects  and 
Method  of  .'Mineraloj.'y,  2m5  ;  character' 
iatlo  In,  313  ;  classes  and  orders  in, 
table  of,  .'tK2  ;  tribes  in,  314  et  .seq.,  321  ; 
Manual  of,  pniposed,  ;t;iK  ;  families  and 
geni^ru  in,  Ohh  ;  binomial  l.atiu  nomen- 
clature In,  ibid. 

Minerals  seeroted  from  basic  rocks,  134, 
i;!8  et  seq.,  220,  .'i07. 

:\lissis8'ppi  valley,  Cambrian  of.  Oil,  023, 
021. 

Mittelgebirge,  Saxony,  202,  478. 

JIolis,  System  of  Minrralogy,  280,  313} 
visit  to  Kdinburgh,  2h(). 

Molecular  weights,  2>>0,  3t<3  ;  relations  o£ 
to  density,  384  et  .fcij.,  392;  volumes, 
291,  302,  304,  319,  376  et  seq.,  379,  384, 391 
et  seq. 

Molecules,  indefinite  divisibility  of,  297. 

Monocraterion,  542. 

Montalban  series,  18.3,  400,  411,  413,  481, 
057  ;  thickness  of,  412  ;  serpentine  and 
chrysolite  rocks  in,  507,  500  ;  veinstones 
of,  223  ;  conglomerates  in,  255  ;  in  New 
llampsliire,  057;  New  York,  007;  Blue 
Kidge,  258  ('<  .leq. ;  Michigan,  nHOet  seq. ; 
Scottish  Highlands,  423,  009  et  seq.; 
Ireland,  423;  Saxony,  202,  255,479;  Ba- 
varia, 482:  St.  C}othard,47l  ;  Alps,  472. 
See  Gneisses,  recent,  cuid  Mica-schists. 
Montarville,  cbrysolitic  dolerite  of,  210, 
605  ;  its  banded  character,  l.O  ;  analy- 
ses of,  212. 
Monteferrato,  Italy,  8erpen*innu,  etc.,  of, 

idO  et  seq.,  iW>. 
Moorr   Ancient  Mineralogy,  307,  note, 
Morlot,  Von,  dolomites,  172. 


I 


702 


INDEX. 


I 


Moro,  liftzfftro,  rruptlvo  rocks,  00. 

Mutt,  •!.  \j.,  terrcHtrlal  onrl)(>ii,  .'tn. 

Mount  Ida,  (Irucco,  chryHoUtu-rocka  of, 
BOO. 

Mount  Uoyrtl,  rnnaila,  orllioolndo  vcinii 
In,  137  ;  ImiwU'  I  ilolcrllo  of,  'JIO. 

Amount  Sorrel,  V.wg.,  rockn  "f,  4'JI. 

MurcliiHon,  K.,  Slliiriim  of,  (I2(,  C2H;  his 
vlow  of  Su()ttlr<h  IllghlandK,  COO;  now 
altiimlonud,  071. 

Murray,  Alex.,  cryslnlUnn  rocks  of  Can- 
ada, WJ  et  Sill- :  lluroiiiiin,  SSI. 

Miirriiy  and  lU'nard,  zuuliteg  In  deep-sea 
ooze,  104. 

NAPiiTltoiDs,  tribo  of,  3S0. 

Nathovst  on  erosion  in  Norway,  27C. 

Natural  Listory,  L'7  ;  jdiilosopliy,  '^7  ;  do- 
flncd  by  I.ooko,  3  ;  soienct's,  ordiT  of, 
27  ;  table  of,  '.'9 ;  systems  as  defined  by 
Kay,  2t*4 ;  system  In  niluoralogy,  li79 
et  seq.,  0H7. 

Naturalist,  slgnKlcatlon  of,  4. 

Nature,  II ipporratfs  on,  8  ;  VIrchowon, 
ifcif/, ;  Uoaniini  on.  IG,  »io/<  ,■  IIund)(dilt 
on,  22  ;  Huxley  on,  iH.natc;  Oken  on, 
23  ;  Klopsioek  on,  23,  nolc;  an  orgaidc 
whole,  20,  note;  kingdoms  of,  27.  See 
Nature  in  Tbouglit,  etc.,  1  et  seq, 

Naturiou,  7. 

Naturist,  8. 

Naumann  on  Hutton,  7B ;  exoplutocto 
hypothesis,  88 1  Dana's  voleanic  liy- 
potlipsls,  94  ;  endoplutonic  hypothesis, 
86,  200 ;  inclined  crystalline  strata, 
111. 

Nebulro,  chemistry  of,  47  et  acq. ;  prob- 
able origin  of,  50,  BO,  65. 

Nephellto,  137,  3.'!8  ;  syenite,  137. 

Neptunlsm  in  geology,  69,  75,  70. 

Neri,  geology  of  Italy,  459,  401,  463 ;  de- 
fines Pietre  verdl,  ibid. 

Nevada,  Cambrian  of,  623. 

Newbury,  J.  S  .  carbon  In  shales,  30. 

New  Urunswick,  geology  of,  407  et  seq.; 
Taconian  In,  572, 

New  Jersey,  crystalline  rocks  of,  058 ; 
Taconian  in,  570.  See  Green-Pond 
Mountain. 

Newton,  Hypothesis  touching  Light  and 
Color,  61,  58  ;  Principia,  58  et  seq. ; 
Optics,  51,  CO;  the  ethereal  medium, 
57;  cosmic  circulation  and  evolution, 
69;  his  anticipations  of  modern  science, 
67 ;  Brewster  on,  52,  69. 


Now  York  City,  geology  of,  (m,  (106 ;  ser- 
pentines of,  4.'l!i. 

Now  York  .State,  geological  survey  of, 
621  ;  Northern  IHstrlct  il>iil.;  Southern 
District,  523;  gneisses  of,  403,  650  H 
Seq. 

Now  Hampshire,  geology  of,  410,  057. 

Newfoundland,  Cambrian  of,  026  ;  Taco- 
nian in,  571. 

New  Hoeheiio,  N.Y.,  serpentine  nf .  4.^.^ 

New  Zealand,  dunlto,  608.  See  Lberzo' 
lite. 

Niagara  limestone,  520. 

Nlcoll,  geology  of  Scottish  Ilighlandi, 
600,071. 

Nlidiic  oxyd  in  silicates,  .100,  ;m. 

NIpigon  grouii  of  Lake  Superior,  678. 

Nittany  Valley,  Pcnn.,  531. 

Nordunskiilld  on  geological  climate,  45  ; 
on  roek-tlecay,  240. 

Norlan  series,  17s,  404,  413,  580. 

North  Carolina,  Kmmons  on  geology  of, 
558  et  Hiq.,  5(i2;  Kerr  on  do.,  5,')8,  WiO, 
501  ;  H.  Wurtz  on,  509  ;  Laureniian  in, 
500  ;  Taconian  In,  .Ifil  et  seq,,  5o:t. 

North  America,  pre-Cambrlnn  of,  402  el 
seq. ;  paleozoic  history  of,  015  et  seq. 

Northbrldge,  Mass.,  metalliferous  veins 
of,  123. 

Notre  Dame  Mountains,  610. 

Notation,  cbondcal  fornndas  in,  302,  312, 
319. 

Novara,  Italy,  serpentines  of,  490. 

Nova  Scotia,  Taconiai\  In,  573. 

Nuttall,  gneisslc  rocks,  403;  metamor- 
phism,  658. 

On.siniAN,  221,  362,  375. 

Ocean,  primitive,  its  nature,  36,  177, 180, 
253  ;  its  temperature,  77,  79,  00. 

Ocrstedlte,  .367. 

Oken,  Physiophllosophy  of,  23;  his  influ- 
ence, 24,  note. 

Oldhamia,  421. 

Olivine.    See  Chrysolite. 

Omaiius  d'Halloy,  eruptive  rocks,  90  ; 
crystallophyllian  rocks,  80. 

Oneida  sandstone  and  conglomerate,  620, 
523,  525,  531,  540. 

Onondaga  salt  group,  527 ;  serpentines  of, 
443  et  seq. ;  gypsums  of,  444. 

Ontario  division  of  New  York  rocks,  522. 

Opaloids,  tribe  of,  370. 

Ophicalcite,  99,  439,  402,  483,  485,  403,  501, 
602.    See  Serpentines. 


INDKX. 


ioa 


[y  of,  fl<W,  (WW ;  Her- 


i;ottlsh  Illglilanda, 


tines  of,  490. 

n  ill,  573. 

ks,  403;   nietamor-  i 


ly  of,  23 ;  his  iiiflu- 


te. 

uptive   rocks,  DC  j 
•ks,  80. 
conglomerate,  5'JO, 

WT ;  serpentines  of, 
of,  444. 
!\v  York  rocks,  622. 

2,  4g3,  485,493,  501, 


OpliltPd  of  ryrorioofi,  isn,  502,  iinff.    .Vcc 

Sfrpi'iitlni'.'*. 
Oplllollti'H.     See  Si'lpriilllH-H. 
Oplut.iUlM.  trllii-  <if,  :iU; ;  tiililo  of,  .1.T». 
Optiin,  Ncwloirn,  51,  57,  5H,  t'.o  ,  f  ne,/, 
OraiiKK  Co.,  N.   V.,  (iniywui'ko  of,  6H9 

I'/  SI  </, 

Oi'tiorH  in  iniiiiTiiiogy,  ial)lo  of,  382 ;  tlieir 
allllliilions,  :iN|. 

Ordwiiy,  .1.  M.,  wator-RlnRS,  119. 

Oi-doviclan  m'ricH,ri:;H,.vJ!i,  (;i!i ;  with  First 
(iiay  wuckf,  Q>:>  it  mn.,  (ill!,  CC7. 

Ornanoni'iiy  ili'llni'cl,  17. 

OrlKkany  HiinilitioiK',  527. 

Ortliocliisc,  It^-.  ili'oay,  ;i2,  247,  240;  veins 
in  liiuiiust^  121  (7  «(Y/.,  in  iloleritc,  t:i7  ; 
111  inotiiUiferouH  lotius,  123  ;  witli  zoo- 
liti'g,  120  it  Mn/, 

Ortliofelsilc,  5t(l.     Si'f  rrtrosilox. 

Ottawa  l)aHin,  i;22  ;  unoonfonuity  iu,  59'J  ; 
UlieisH,  412,  11.1. 

Oxycollolils,  Irilie  of,  370. 

Oxyiliiti's,  onler  of,  ;)'jo,  ;i7fi. 

Oxyduinantoiils,  tribe  of,  37C ;  volumes 
of,  ibitl. 

OxyiiH,  native  sources  of,  1,50,  181,239; 
a.tsoclati'tl  Willi  silieatuM,  IHI,  239. 

Oxygen,  (llslriliiilion  of  in  space,  41 ;  re- 
lation to  cmtionio  ilioxyil,  35;  libera- 
tion of  in  organic  processes,  33,  3U. 

Oxyphylloids,  trilte  of.  .'!7C. 

OxyspatUoiils,  tril)o  of,  37C. 

P  =  UNIT  WKinnT,  303  et  scq.,  301 ;  bow 
calculated,  .'?2fi. 

ralagfinito,  120,  1.52,  150;  artificial  pro- 
duction of,  l;!0;  eliango  to  a  zeolite, 
120,  374  ;  silicated  protoplasm,  1«8,  3G2, 
374. 

Paleotrochis  of  Kniiiions,  501. 

Paleozoic  history  of  Xorth  America,  C15 
et  scq. 

Pallas,  crystalline  rocks,  CO ;  rock-decay, 
247. 

Pantanelll,  phthanitcs,  490,  note. 

Paragonite,  101,  102,  .357. 

Pargasite,  310,  345. 

Paris  basin,  nepiolites  of,  448. 

Parmentier,  niolybilates,  388,  note. 

Parophite,  1(M. 

Passaiiiaquoildy  Bay,  petrosilex  of,  647. 

Passau,  Uavaria,  kaolin  of,  371. 

Patrin,  serpentine,  426. 

Pebidian  series,  417  et  seq.,  422  et  seq., 
449;  upper,  423,  670. 


Pe(  llHntloii,  of  riralmn),  .115,  ,122. 
I'rTtiillti',  I'tymcdogy  of,  ;\St,  xnle, 
I'eetolitiu  silicatun,  13N,  140,  147,  178;  list 

of,  ir,. 
I'ec|ollioidi<,  trilie  of,  ;!15  ;   table  of,  323. 
I'elljitl,  Italian  serpentines,  1,51,  474,  484, 

4.'(I.  4HH. 
Penilirokcsliire,  geology  of,  41C, 
renlleld,  lieryl,;H7. 
I'ennsj  ivaiila.  geology  of,  5,10  ft  *eq. 
Peradanmntoids,  Ir'ljo  of,  318;  tublo  of, 

.'Km. 

Pcrlite,  221,  .102,  .175. 

Porpiiylloids,  trilic  of,  .118  ;    table  of,  ,K1R. 

Perry,  •!.  h..  limestone  veins,  230 ;  Ued 
Sand-roek,  0;>0  ;  Taconian,  iliul. 

I'eisilieates,  sub-order  of,  306  et  ten,; 
table  of,  401. 

Peispallioids,  trilie  of,  318,  .106. 

lVr/.e(ditoids,  :117,  .10.5. 

IVtalite,  2:10,  231,  340,  0H7. 

I'etralogy,  IMiikerton's,  427,  note;  com- 
parative of  Iiiiroclicr,  L'liH,  214  et  siq. 

Petrosilex  series ^.Vrvoldanl,  408,  410,  41H ; 
ill  Wiscon.Hin,  410,  540;  Missouri,  10.1, 
200, 4!iH;  I'ennsylvania,  510  ;  Massachu- 
setts, 40.S  (7  mil. ,  New  Hruiiswick,  400, 
540,  rA' ;  Lake  Superior,  410;  Wales, 
4Ih;  111  Scotland.  424  i  Alps,  515,  iio^-; 
Sweden,  419,  470  ;  conglomerates  of, 
41!i,  420. 

Phillips,  John,  two  igneous  magmas,  87, 
207. 

Phillips,  J.  Arthur,  rocks  of  Cornwall, 
4.50. 

Philosophical  Society  of  Cambridge,  61, 
07. 

Phiisphates,  complex,  388. 

Pliospiiotungstates,  ;ihO,  387,  302. 

Piiosplioiiiolyliilates,  3S0. 

I'hiderite,  its  liistory,  367. 

Phoiiolite,  (u-igin  of,  218. 

Phthanite,  488,  400,  iiore. 

Phyllograptus  shales,  625,  C2C. 

Phylluid  type,  310,  374. 

Physic,  defined,  1-11  ;  general,  17. 

Physics.    Si.'V  I'liysio. 

Physician,  7,  lo;  defined,  7,  vote. 

Physiology,  general,  2-7,  11,  12,  18,  21  ;  of 
Ionian  school,  4  ;  mental,  5,  vote;  ani- 
mal, 11  t<  stry./  vegetable,  25 ;  mineral, 
26,  28,  29. 

Physiography,  scope  of,  17,  22,  27. 

Picotite,  148,  508. 

Pi    -olite,  324. 


I  <'l 


704 


INDEX. 


Pietre  verill  (greenstone)  growp,  411,  45G, 

459  et  acq.,  4G3  et   sirj..  472,   477,  514  ; 

thickness  of,  405 ;  UastiilJi  on,  464, 483  ; 

Neri  on  4C.'3,4r>4;  is  Iluroni.an,  D82.  See 

Huroni.'in  diul  Ureuustone. 
rilolite,  360. 
Pinit3  and  related  species,  163  et  seq,, 

1C4,  note,  301,  303. 
riniti)ids,  tribe  of,  317  ;  table  of,  361. 
Pinkerton's  PetralDgy,  427,  note. 
Pitchstond,  221,  302,  375. 
Planets,  alnmsphores  of,  46,  47. 
Playfair,  John,  exposition  of  Ilutton,  68, 

74,  75  j  biography  of,  sO,  note. 
Plenum  of  Descartes,  57, 62. 
Plonibiiires,  thermal  spring  of,  150  et  seq, 
Plutonic  substratum,  115,  117,  118,  132  et 

seq.,  175,  179  ;  secular  changes  in,  131, 

178, 207, 214,  218, 244  ;  Prestwich  on,  118, 

note ;  rocks,  relations  of  to  metamor- 

phic,  432. 
Plutonists,  74,  75,  217.    See  Eudoplutonic 

and  Kxoplutouic. 
Pollucito,  331. 

Polycarbonates,  289,  290,  298,  304,  386. 
Polymerism  in  mineral  species,  285,  286, 

289,  377,  394.    See  Condensation,  en. 
Polysilicates,  286,  289,  298,  3U},  393. 
Porodini,  Ureithaupt's  order  of,  383. 
Porodinous  (Porodic)  species,  383,   687. 

■See  Colloids. 
Port  Henry,  N.  Y.,  limestones  of,  237. 
Portsmouth,  B.  I.,  amiunthoid  silicate  of, 

195,  359. 
Potsdam,  sandstone,  521,  526, 534, 577,611, 

C24  ;  deposition  of,  618  ;  Lesley  ou,  660, 

note;  Lower,  618,624,637. 
Poussin,  De  la  Vallee,  and  RiSnard,  geol- 
ogy of  the  Ardennes,  422. 
Po.vell,  J.  W.,  Grand  Cafiou  group,  624. 
Prato.    See  Monteferrato. 
Prehnite,  143  ;  is  an  adamantoid,  347. 
Pre-Cambrlan  rocks,  history  of,  402  et 

seq. ;  in  Nortli  America,  402 ;  Europe, 

416  et  seq. ;  literature  of,  113,  note. 
Pressure,  its  elfect  on  solution,  222. 
Prestwich,  T.,  on  a  solid  earth,  1!S. 
Priestley,  J.,  address  at  grave  of,  49,  C5, 

396. 
Pr-mal  series  of  Rogers,  533,  542  et  seq. ; 

thickness  of,  542,  .543  ;  slates  of,  544,547, 

548  ;   iron-ores   of,  650  ;    in   Virginia, 

602. 
Primary   plutonic  rock.     See  Plutoflo 

substratum. 


Prime,  F.,  geology  of  Pennsylvania,  540 

etseq. 
Primitive  Clay-slate,  481,  482,  684. 
Primitive  Lime-rock  of  Katon,  519,  529, 

554.    See  Taconian,  limestones  of. 
Primitive  Quartz-rock  of  Katon,  519, 529, 

554.    See  Taconian,  quartzites  of. 
Primitive   rocks,  69,  70,  190,   402,  530; 

Lehman  on,  69 ;  Werner  on,  70. 
Primitive  schists  of  Lory,  406. 
Principia,  Newton's,  58  et  seq.,  6J,  note, 

62,  note. 
Protadamantoids,  tribe  of,  315 ;  table  of, 

3211. 
Protogine  of  Alps,  46G. 
Protoperauamantoids,  tribe  of,  317;  table 

of,  345. 
Protoperphylloids,  tribe  of,  317;  table  of, 

354. 
Protoperspathoids,  tribe  of,  310 ;  table  of, 

337. 
Protophylloids,  tribe  of,  31G;   table  of, 

S31. 
Protospatholds,  tribe  of,  315;  table  of, 

327. 
Protosilicates,  sub-order  of,  305,  r07,  314; 

table  of,  399. 
Protojiersilicates,  sub-order  of,  305,  307, 

316  ;  table  of,  400. 
Protoplasm,  dettned,  18 ;    mineral,  188, 

374. 
Prntoxyd-silicates,  table  of,  145. 
ProuKtoids,  tribe  of,  379. 
Pseudomorphism,  83,  li'O,  101,  note,  303. 

See  Metasomatism  and  Metamorpbism, 
Psychology,  limits  of,  18. 
Pulaski  shales,  520,  524  et  seq, 
Pumpelly,  metasoiiiatosis,  103,  498 ;  zeo- 
lites, etc.,  of  Lake  Superior,  143  ;  rock- 
decay,  249.  209,  274  ;  erosion,  275. 
Pyrallolite,  333. 

Pyrenees,  serpentines  of,  483,  502,  note, 
Pyricaustates,  order  of,  380. 
Pyritoids,  tribe  of,  378. 
Pyrites,  associated  with   limonite,  259, 

261,  555. 
Pyrognondc  minerals,  96. 
Pyropliyllite,  309,  425,  ?jo/e;  of  Taconian, 

561,  503. 
Pyroxene,  290,  .328,  ,330,  393;  formation 

of,  148,  220  ;  aluminous,  213,  310. 
Pyroxenite  veinstone,  225,  227. 
Pythagoras,  school  of,  3. 

QuANTiVALENT  ratios  of  silicates,  310. 


INDEX- 


705 


Pennsylvania,  540 


i  of,  315 ;  table  of, 


itU   limonite,  269, 


0,  393;  formation 
us,  213,  310. 
225,  227. 


of  silicates,  310. 


Quartz,  varieties  of,  138 ;  volume  of,  377 ; 
artificial  formation  of,  148, 149, 157, 216, 
218,  219;  fusion  of,  209,  note;  fluorhy- 
dric  acid  on,  687  ;  supposed  eruptive, 
95, 96, 429 ;  -rock.  See  Primitive  Quartz- 
rock. 

Quartzlto  group  of  Uominger,  580. 

Quenstedt,  primeval  atmosphere,  114. 

Quebec  group,  518,  585  et  seq.,  5!)6  et  seq,, 
603,  609,  617  ;  Logan  on,  G34 ;  inverted 
by  him,  596, 634  ;  altered,  of  Logan,  406, 
410, 610.  See  First  Graywacke,  Hudson- 
River  group,  and  Taconic  slates. 

Quebec  city,  geology  of,  Emmons  on,  584, 
585  ;  Logan  on,  594 ;  section  at,  596,  634. 

Rammelsbero,   chemical    mineralogy, 

282  ;  studies  of  tourmalines,  lii2,  350  et 

seq. ;  micas,  359. 
Kay,  John,  natural  systems  in  classifica- 
tion, 284. 
Beading,  Penn.,  iron-ores  of,  551. 
Ked  Sand-rook  of  Vermont,  593,  608,  630, 

638. 
Refrigeration   of    the  earth,   114,   117 ; 

Ssemann  on,  47. 
Rensselaer  Co.,  N.  Y.,  laconic  slates  of, 

586,  627. 
Renevier,    amorphous    chabazite,    154 ; 

geology  of  the  Simplon,  466. 
R^nard,  geology  of  the  Ardennes,  422; 

coticulite,  425,  note. 
R^uard  and  ^Murray,  zeolites  in  deep-sea 

ooze,  154. 
Rensselaerite,  333. 
Resinoids,  tribe  of,  380. 
Betinalite,  332,  435,  note, 
Reusch,  crystalline  rocks,  93  ;  erosion  in 

Korway  ami  Corsica,  276  ;  and  Brogger, 

apatite  of  Norway,  236 ;  Iherzolite,  508. 
Reynolds,  O.,  physiology,  5,  note. 
Rhode   Island,  Taconlan   in,  257;   new 

silicate  from  anthracite  of,  195,  360. 
Riohthofen,  aerial  erosion,  275. 
Rideau,  apatite  mining  district,  224. 
Rifts  or  divisional  planes  in  rocks,  274, 

note. 
Rigaud  Mountain,  Quebe'5,  boulders  of 

decay  on,  271. 
Rivot,  geology  of  Lake  Superior,  612. 
Robb,  Ch.,  garnet  with  prehnlte,  121. 
Rock-basins,  origin  of,  252. 
Rock-salt,  supposed  eruptive,  90  ;  of  the 

Alps,  4G8. 
Rocks,  crystalline  (see  Crystalline  rocks); 


indigenous,  72  ;  exotic,  73  ;  endogenous 
ibid. ;  igneous,  eliqualion  in,  189,  208  et 
seq.,  245 ;  secular  changes  in,  187,  253  ; 
solid,  intruded,  73, 204, 512  ef  seq. ;  dutri- 
tal,  changes  In,  108,  o72,  tm. 

Rock-decay,  sub-aerial,  246  et  aeq.,  277, 
308  ;  Its  antiquity,  236,  270  ;  its  chem- 
istry, 31  et  seq.,  250 ;  relations  to 
erosion,  251,  271,  274  et  seq. 

Rogers,  Henry  D.,  calcareous  veins,  229; 
crystalline  rocks,  405  et  seq. ;  eruptive 
quartz,  iron-ore,  etc.,  95,  429;  llypo- 
zoic  and  Azoic  rocks,  405,  661 ;  the 
White  Mountains,  658,  663  ;  geology  of 
Pennsylvania,  533,  543;  his  strati- 
graphical  divisions,  553;  Taconic,  628. 

Rogers,  William  B.,  rock-decay,  258 ; 
formation  of  iron-carbonate,  266 ;  Red 
Sand-rock  of  Veru)ont,  630  ;  Taconlan, 
628,  631,  664  ;  crystalline  rocks  In  Vir- 
ginia, 661  ;  geology  of  the  Blue  Ridge, 
662. 

Rogers,  Messrs.,  cited  by  Dana,  664. 

Rolljstiin  Hill,  Mass.,  gneiss  of,  274,  note. 

Romlngur,  geology  of  Michigan,  579  et 
seq. 

Roofing-slates,  Lower  Taconic,  525,  538, 
555,  571,  578,  580,  589,  592,  675  (see  Argil- 
lite,  Transition) ;  Upper,  555,  592. 

Roscoe,  H.  £.,  a  new  inorganic  chemis- 
try, 389, 

Rosenbusch,  Iherzolite,  508. 

Rosinini,  philosophy  of  nature,  16,  note. 

Rougemont.  Quebec,  dolerite  of,  210,  506. 

Royal  Institution,  London,  53. 

Russia,  diamond  region  of,  565,  680. 

Rutile,  377  ;  of  Taconlan,  503,  568. 

S.«:mann,  a  cooling  earth.  47. 
SatTord,  geology  of  Tennessee,  559. 
Saint  David's,  Wales,  rocks  of,  416. 
Saint  Gothard,  Mount,  geology  of,  73, 

204,  470;   tunnel  of,  470;  gneisses  of, 

470,  471,  613  ;  serpentine  of,  511  et  seq. 
Saint  Helen's  Island,  Montreal,  geology 

of,  604,  631. 
Saint    John,  N.  B.,  Taconlan  of,  672  ; 

Lower  Cambrian  of  (St.  John  group), 

623  (see  Menoviaii). 
Saint  Ours,  alkaline  water  of,  218. 
Saint  Peter's  sandstone,  611,  623. 
Salinoid  type,  380. 
San  Domingo,  geology  of,  683. 
Santorin,  lavas  of,  213. 
Sapoulte  in  zeolitlc  rocks,  139. 


706 


INDEX. 


!!v 


'  1 


'  1 

•I 


Sardinia,  geology  of,  475. 

Sauer,  cunglouiarates  in  crystalline  rocks, 
183,  255,  479. 

Saiissure,  granites,  71,  72;  serpentines, 
427. 

Siiussurite,  299,  301,  348,  451. 

Savi,  igneous  limestones,  228,  477;  sor- 
penti'.ies  or  ophiolites,  428, 451. 

Saxony,  granulites  of,  202,  255,  478; 
dichroite-gneiss  of,  478;  gabbro  of,  ibid. ; 
serpentines  of,  479. 

Scnpolites,  300  at  seq.,  340  et  seq. ;  inter- 
mediate species  of,  295,  342. 

Scandinavia,  gneisses  of,  404. 

Schelliug,  23,  note;  life  in  matter,  21, 
note. 

Scblel,  progressive  or  homologous  series 
in  chemistry,  289. 

Scheerei,  ^yrognoiuic  minerals,  96;  water 
in  granites,  96;  hydrous  iolites,  143; 
crystalline  admixtures,  294 ;  serpen- 
tines, 504. 

Schorlite,  a  tourmaline,  351. 

Schulten,  l>e,  artificial  production  of 
zeolites,  etc.,  157  et  seq. 

Scolithus  linearis,  534,  542,  554,  note,  567, 
615,  676 ;  Canadensis,  554,  note ;  of  the 
Medina,  634  ;  of  Hastings  rocks,  576 ; 
sandstone,  414,  544  et  seq.,  548,  554,  660. 

Scotland,  ancient  gneiss  of,  404 ;  decay 
of  rocks  in,  271 ;  Highlands  of,  423, 424  ; 
liistory  of  their  crystalline  rocks,  669 
et  seq. 

Scott,  Walter,  the  word  mediciner,  10. 

Scrope,  Poulett,  New  Theory  of  the 
Earth,  81,  201 ;  hydrothernial  hypothe- 
sis, 81,  96;  granites,  81 ;  volcanoes,  96, 
201  ;  Igneous  rocks,  210,  222  ;  lamina- 
tion by  movement,  81,  201. 

Sea-water,  sovirce  of  magnesia  in,  180, 
182  ;  removal  of  from,  177, 182 ;  fossil, 
253. 

Second  Oraywacke,  520,  622,  520,  630,  684, 
{■*5,  620,  677  ;  its  relation  to  Transition 
Argillite,  632;  overlies  First  Gray- 
wacke,  686,  698,  600,  627  ;  overlies  Cam- 
brian and  Ordovician,  599;  confounded 
with  First  Graywacke,  698,  649,  654. 

Secondary  rocks  of  Werner,  70, 190. 

Secretion  of  minerals  from  basic  rocks, 
134,  135  et  seq.,  220,  307. 

Secular  variation  In  composition  of  rocks, 
113,  187,  214,  216,  253,  678. 

Sedgwick,  rocks  of  Wales,  416  j  Cambrian 
divisions  of,  624,  628. 


Sella,  Qulntlno,  geology  of  Jjombardy. 
462,  496. 

Selwyn,  A.  R.  C,  pre-Cambrian  rocks, 
424 ;  Ordovician  in  province  of  Quebec, 
607. 

Senarmont,  H.  de,  serpentines,  428,  note  ; 
artlflcial  production  of  corundum  and 
diat^^ore,  501. 

Sepiolite  of  lertiary,  119.  185, 196,  448. 

Sericite-schists,  161,  467,  474,  683. 

Serpentines,  426  «t  seq. ;  intrusive,  95, 427, 
428, 429,431, 452, 456, 469, 483, 486, 495,497, 
509 ;  metasoniatic,  431,  450,  452,  498  (see 
Metasomatism);  metamorphic,  486, 499 ; 
hydroplutonic,  97,  487,  492,  500;  in- 
digenous, 430,  431,  433,  448,  486,  501  et 
seq.,  503,  51? ;  decay  of,  268,  441 ;  dehy- 
dration of,  606 ;  chrysolite  from,  500, 
513  (see  Chrysolite) ;  stratigraphical 
relations  of,  427,  428,  483  et  seq.,  492, 
509, 510,  511  et  seq.;  grauulite  with, 439 ; 
granite  vein  in,  438 ;  conglomerates 
and  breccias  of,  453,  493,  495  ;  veins  of, 
453,  609;  Laurentian,  332,  435;  Huro- 
nian,  436  ;  Montalban,  437  ;  Taconian, 
442,  673  ;  Silurian,  185,  iiSet  seq.;  sup- 
posed tertiary,  455  et  seq.,  486,  515  ;  of 
North  A  merica,  434  et  seq. ;  New  Ro- 
chelle,  N.  Y.,  435  ;  New  York  City,  439 ; 
Staten  Island,  440,496;  Hcboken,N.  J., 
441 ;  Syracuse,  N.  Y.,  443  ;  Cliester  Co., 
Penu.,  437  et  seq.;  Cornwall,  Penn.,  442 ; 
North  Carolina,  438,  507 ;  Lake  Supe- 
rior, 579;  Europe,  449  et  seq. ;  Scotland, 
427,  510  ;  Cornwall,  i^ug.,  428,  449,  510 ; 
Saxony,  479;  Mount  St.  Gothard,  511 
> .  seq.,  513  ;  Alps,  427,  4C3, 465, 469, 472 ; 
Apennines,  455,  456,  487  ;  the  two  re- 
gions compared,  484  ;  Italy,  450  et  seq., 
482  et  seq.;  Liguria,  452,  485;  Sestrl 
Levante,  495  et  seq. ;  Tuscany,  452  ; 
INIonteferrato,  490  et  seq.;  Lombardy, 
Biellese,  463,  496;  Corsica,  474;  of 
Elba,  475  ;  Emmons  on,  428 ;  Mather, 
441 ;  E.  Hitchcock,  428  ;  Bonney,  449, 
450,  462,  495 ;  Goikie,  610 ;  King  and 
Rowney,  498;  Stapff,  501,  511  et  seq.; 
Delesse,  431,  432;  Daubr»5e,  600;  Qas- 
taldi,4S3,  486;  Gras,432,-io<e,-  Lory, 469; 
Tarnmelli,487;  Issel  and  Mazzuol',487; 
Capaccl,  492  ;  Cossa,  484  :  Pellati,  454 
et  seq.,  484,  488  ;  Lotti,  474,  502  ;  Dieule- 
fait,  474,  601,  602,  vote;  public  discus- 
sion on,  at  Bologna,  454.  See  Ophical- 
cite. 


INDEX. 


707 


of  Ijombardy, 

mbriaii  rocks, 
ace  of  Quebec, 

tines,  428,  no<e  ; 
corundum  and 

185, 196,  448. 
74,  683. 

jtrusive,95,427, 
483,486,495,497, 
450,  452,  498  (see 
orphic,l86,499; 
,  492,    500;    in- 
448,  486,  501  et 
,  268,  441 ;  dehy- 
olite  from,  500, 
Btratigrapbical 
483  et  seq.,  492, 
uulite  with,  -139 ; 
conglomerates 
13,  495  ;  veins  of, 
332,  435;  Huro- 
437  ;  Taconian, 
443  et  seq, ;  sup- 
«eq.,  486,  515  ;  of 
!  seq.;  New  Ito- 
[v  York  City,  439 ; 
Hcboken,N.  J., 
43 ;  Chester  Co., 
all,  Penn.,  442 ; 
17  ;  Lake  Supe- 
leg.  ,■  Scotland, 
_;.,  428,  449,  510  ; 
St.  Gothard,  511 
4C3, 465, 469, 472 ; 
the  two  r©- 
aly,  450  et  seq., 
452,  485;  Sestrl 
Tnsi^any,  452  ; 
Lonibardy, 
orsica,   474;    of 
428;  Mather, 
Bonney,  449, 
510;    King  and 
501,  511  et  seq,; 
ihrie,  500;  Qas- 
,io(e,- Lory,  469; 
ldMazzuol!,487; 
i84 :  Pellatl,  4,54 
474,  502  ;  Dieule- 
publie  (Uscus- 
See  OpUical- 


Sestrt  Levante,  serpentines  of,  495. 

Sharpe,  laminated  rocks,  201. 

Shalcr,  N.  S.,  origin  of  iron-ores,  267; 
divisional  planes  in  rocks,  273,  note. 

Shawangunk  Mountain,  geology  of,  520, 
588. 

Shenstone  and  Tilden,  solution  at  high 
temperatures,  221. 

Shepard,  C.  U.,  dysyntrlblto,  163  ;  calca- 
reous veins,  229 ;  rock-decay,  248  ;  11- 
monites,  2G4  ;  Treatise  on  Alineralogy, 
282. 

Slderlte,  261,  262,  265.  267,  481,  535,  673, 
680,  674,  684.    See  Iron  Carbonate. 

Siemens,  C.  W.,  sol.ar  energy,  51. 

Silicates,  order  of,  305 ;  its  three  sub- 
orders, 305  ei.wf/.  ,•  their  inter-relations, 
311 ;  tribes  of,  314,  321 ;  list  of  species, 
321 ;  synoptical  tables  of  sub-orders, 
399  et  seq. ;  Breithaupt's  classitication 
of,  281,  3S3.«o<e,-  protoxyd-,  table  of, 
145 ;  zeolitic,  etc.,  table  of,  141 ;  dis. 
sociation  of,  148,  156 ;  inti-rchange  of 
bases  In,  159  et  seq.;  water  in,  291,  298  ; 
their  secretion  from  basie  rocks,  134, 
135  et  seq.,  220,  307  ;  their  relation  to 
decay,  308;  Laurent  on,  297  et  seq.; 
complex  formulas  of  (see  Polysilicatos) ; 
condensation  in  (.see  Condensation) ; 
molecular  weight  of,  290,  385,  393  (see 
Polymerism). 

SlUciflcation  In  decaying  gravels,  272. 

Silicon  series,  the,  288. 

Sillcotungstates,  380  et  seq.,  389. 

Sillery  sandstone,  594,  596,  603,  634. 

Silurian,  sea  in  Korth  America,  605,  620  ; 
limestones,  their  distribution  in,  020  ; 
relation  to  Ordovician,  005. 

Simplon,  geology  of,  466. 

SmaltoUls,  378. 

Smith,  Eugene  A.,  geology  of  Alabama, 
557,  560. 

Smoky  Mountains,  Tennessee,  559. 

Smock,  on  Green-Pond  Mountain  belt, 
591. 

Snowdon,  AVales,  420. 

Societi  Geologica  Italiana,  451. 

Sodalite,  342. 

Sodium-chlorid,  varying  density  of,  394 

,  et  seq. 

Soda-dolomite  of  Deville,  171. 

Solar  physics,  51,  53  et  seq.,  61  et  seq,  ; 
heat,  source  of,  58,  64. 

Solution,  nature  of,  16 ;  at  high  tempera- 
tures, 221. 


Solubility,  temporary,  of  bodies,  167 ;  of 
colloids,  168. 

Si)ljoarne,  Sweden,  conglomerates  of,  479. 

Sorby,  H.  C,  crystallization  around  nu- 
clei, 174 ;  relation  of  pressure  to  solu- 
tion, 222. 

South  Carolina,  geology  of,  563  e«  se5.,670; 
IJeber  on,  565. 

South  iMountain  belt,  257,  405,  546,  549, 
657,  656. 

Spain,  geology  of,  685. 

Spar,  order  of,  Mohs,  281,  313  ;  its  gen- 
era, iliifl. 

Sparry  limestone.  See  Sparry  Lime-rock. 

Si)arry  Limo-rock  of  Katon,  520,  526,  527, 
529,  585,  608,  617, 027, 029,  643, 645  et  seq.,' 
647,  6-19,  676 ;  its  tllstribution  and  age, 
645  et  seq.;  James  Hall  on,  587,  608; 
Billings  on,  634,  note, 

Spathoid  type,  314  et  seq, 

Spathometallates,  sub-order  of,  379. 

Specific  gravity,  304,  391,  394  et  seq, 

Spencer,  Herbert,  on  colloids,  19. 

Sphaleroids,  379. 

Spinels,  148,  376,  .o08. 

Spodumene,  .349,  687. 

Stallo,  J.  B.,  on  physiophilosophy,  18,  23, 
24,  note ;  on  hypotheses,  679,  note, 

Stannipyrite,  tin  pyrites,  379. 

Stars,  chemistry  of,  47  et  seq, 

Staten  Island,  N.  Y.,  mesozoio  of,  440, 
659  ;  serpentine  of,  440, 496,  659  ;  limo- 
nitos  of,  268. 

Statics,  12. 

Staurolite,  214,  350;  In  Taconian,  184, 
508  ;  its  admixture  with  quartz,  364. 

Steatite,  supposed  eruptive,  429 ;  in  T.v 
conian,  561. 

Stewart,  Diigald,  physiology,  4. 

Stockbriilge  limestone,  554,  585.  See 
Taconian,  limestones  of,  and  Primitive 
Lime-rock. 

Stoichiogeny  defined,  24. 

Stone  Mountain,  Georgia,  2,58,  274,  note, 

Storer,  F.  II.,  rock-decay,  246. 

Stratiform  structure  In  eruptive  rocks, 
81,  89,  200  et  seq. ;  dolerites,  210  ;  dia- 
base and  granites,  211,  note;  Scrope 
on,  81,  201 ;  J.  D.  Dana  on,  89,  201 ;  in 
veinstones,  224,  226,  230,  234  et  seq. 
See  Lamination. 

Stratigraphic.al  breaks,  583 ;  in  Atlantic 
belt,526,  598,  604,  621. 

Struve,  molybdates,  388,  note. 

Stubbs,  rock-decay,  246. 


Ml 


708 


INDEX. 


V'i 


A  i  ■ 


Ul 


Sub-aerial  decay.    See  Rook-dooay. 

Sulphatosalinoid  type,  3S0. 

Sulphur,  supposed  eruptive,  06 ;   native 

In  dolomite  of  Syracuse,  N.  Y.,  445. 
Sulphuretted  silicates  and  oxyds,  293, 303, 

327,  342,  344,  379,  381. 
Sun,  chemistry  of,  M ;  source  of  Its  hf  at, 

51,  58,  62,  64. 
Survival  of  the  fittest,  165,  363. 
Sweden,  conglomerates  of  SoljQarne,  479 ; 

biilleflinta  of,  419,  479. 
Sweet,  E.  T.,  on  kaolin,  254,  270. 
Synopsis  ^lineralogioa  of  Weisbach,  381. 
Synoptical  tables  of  native  silicates,  399, 

400   101. 
Syrajuse,  N.  Y.,  serpentine  of,  185,  443 

et  seq.,  447. 

Table  Mountain,  Col.,  zeolites  of,  136. 

Tables:  olassiflcation ot  natural  sciences, 
29;  Eaton's  geological  classification, 
529  ;  atomic  weights  and  synilmls,  320 ; 
minei'alogical  system,  382 ;  synoptical 
of  sub-orders  of  silicates,  399-401 ;  of 
zeolites  and  related  species,  141 ;  of 
protoxyd-silicates,  145.  (For  various 
tribes  of  silicates,  see  under  respective 
titles.) 

Tachyllte,  130,  note,  154,  362. 

Taconian,  414,  415,  467,  481,  578  et  seq., 
682,621  et  .leg.,  674  c'<  seq,;  quartzites 
Of,  642  et  seq.,  544,  554,  556,  558,  561  et 
seq.,  564,  50G,  573,  580,  674  (see  Primi- 
tive Quartz-rock  of  Eaton);  limestones 
of,  535,  541,  654,  557,  SCO,  572,  575,  580, 
674, 682, 684  {see  Primitive  Lime-rock  of 
Eaton);  slates  of  («ec  Magnesian  sla^^es 
and  KooflDg-slates) ;  serpentines  of, 
442,  473 ;  iron-ores  of,  535  et  seq.,  550  et 
seq.,  568,  570,  671 ;  zinc  of,  536,  538  ; 
graphite  of,  561,  573, 680,  682 ;  diamonds 
of,  563,  664  et  seq.,  680 ;  gold  of,  568 ; 
rutile  of,  563,  568  ;  mineralogy  of,  184, 
635,  661,  568,  674  ;  decay  of,  249,  261,  263 
et  seq. ;  thickness  of,  635,  541,  583,  672, 
675,  645,  674  ;  relations  to  organic  life, 
567,  5*3,  675,  678,  582,  676  ;  confounded 
with  Huronlan,  560,  579,  681,  614 ;  re- 
semblances to  Champlain  division,  653 ; 
literature,  673,  note ;  views  as  to  age  : 
Maclure  on,  557 ;  P:aton,  529,  627,  629, 
652  i  Emmons.  522,  562,  585,  627  et  seq., 
644  et  seq.,  675  ;  Mather,  628,  649.  651  ; 
H.  D.  and  W.  B.  Uogers,  628,  651;  W. 
B.  Rogers,  631 ;  Kerr,  658,  660  ;  Lieber, 


565  .'<  seq. ;  Wing,  633  ;  Perry,  636 ;  Mar- 
cou,  ibid. ;  Adam  j,  600  ;  E.  Hitchcock, 
631 ;  Logan,  634,  637,  649 ;  J.  D.  Dana, 
Pi2,  645,  651 ;  various  views  resumed, 
648;  distribution  of  in  Appalachian 
valley,  556  et  seq. ;  Massachusetts,  519, 
653,  562;  Vermont,  671,  574 ;  Quebec, 
571;  New  Jersey,  570  et  seq.;  Pennsyl- 
vania, 534  et  seq.,  541  et  seo.,  537,  543, 
649,  556;  Virginia,  556,  55? ;  North 
Carolina,  557  et  seq.,  602,  569 ;  South 
Carolina,  5G3  et  seq.,  567;  Alabama, 
567  ;  Georgia,  563  ;  outside  of  Appala- 
chian valley,  657  et  seq. ;  Rhode  Island, 
672 ;  JIaine,  572  ;  New  Brunswick,  572, 
674;  Nova  Scotia,  573;  St.  Lawrence 
Co.,  N.  Y.,  576  et  seq.,  IlasUngs  Co., 
Out.,  574  et  seq.,  676  ;  Michigan,  580, 
675;  Minnesota,  578,  580;  Lake  Su- 
perior, 578  ;  Utah  and  Dakota,  676 ; 
Arkansas,  676 ;  Trinidad  and  Guiana, 
681  et  seq. ;  Cuba,  682  ;  Brazil,  564,  680  ; 
tbe  Alps,  473,  684  ;  Bavaria,  482,  684 ; 
Italy,  415,  467,  683,  684 ;  Spain,  685 ; 
Norway,  ibid. ;  Russia,  565, 680  ;  Hindo- 
stan,  564,  6k>0. 

Taconic  slates,  group  of,  527,  585,  627; 
called  Upper  Taconic,  527,  630  ;  subdi- 
visions of,  644 ;  limestones  of,  646  et  seq. 
(see  Sparry  Lime-rock) ;  fossils  of,  586, 
647;  equivalent  to  Calciferous  Sand- 
rock,  587;  overlies  Transition  Argillite, 
ibid,  i  overlaid  by  Second  Graywacke, 
686,  598,  600,  627.  Is  First  Graywacke, 
and  Quebec  group,  which  see;  also, 
Hudson-River  group. 

Taconic  hills,  geology  of,  553  et  seq.,  627, 
643,  645. 

Taconic  system,  617  et  seq. ;  Lower  (see 
Taconinn) ;  Upper  (see  Taconic  slates). 

Talc-scaists  of  Lory,  '66. 

Taramelli,  geology  of  Italy,  456,  478. 

Tennessee,  Taconi,an  of,  659. 

Terranovan  series,  480. 

Tertiary  strata,  190;  limonites  of,  263, 
lu^te;  in  Italy,  474,  485,  490  et  seq.,  496, 
616. 

Tcschenite,  137. 

Tesori  Sotteranei  del'  Italia,  Jervis,  477. 

Texas,  geology  of,  621, 624. 

Theologians  on  Hutton  and  Werner,  76. 

Thermal  springs,  mineralogy  of,  160  et 
seq. 

Thermoohaotic  hypothesis,  82,  105, 10i». 

Thermodynamics,  26. 


K-l^-ir-il 


INDEX. 


709 


',  553  et  seq.,  627, 


sis,  82,  105,  10^. 


Thiogalenoids,  tribe  of,  379. 

Thoinsou,  Win.,  on  Imerstellar  space, 
63. 

Thorasonite,  1-12,  334. 

Thomson,  ISIinn.,  argilUtes  of,  578,  580. 

Thunder  JJay,  Lake  Superior,  678,  611. 

Ticino,  Italy,  geology  of,  470  et  seq. 

Tilden  and  Sheiistone,  solution  at  high 
temperatures,  221. 

Tintio  Hills,  Utah,  geology  of,  676. 

Tonto  group,  624. 

Toreil,  crystalline  rocks,  418,  419. 

TOrnebohm,  crystalline  rocks,  93 ;  Iherzo- 
lite,  508. 

Torrance,  J.  F.,  apatite-veins,  224,  232, 
notes. 

Tourmalines,  138, 101,425,  wo^e;  composi- 
tion of,  350  et  seq. ;  table  of,  353. 

Tozzetti,  gabbros,  451. 

Trachyte,  origin  of,  133,  186,  187,  217; 
Bunsen's  normal,  129,  note. 

Transmutation  of  rocks,  doctrine  of,  98, 
100, 102.    .See  Metasomatism. 

Transition  Graywaoke  series  of  Eaton 
(see  First  Graywacke) ;  rocks  of  Wer- 
ner, 70, 100,  190,  402. 

Trenton  limestone,  521,  537,  540  et  seq.  ; 
its  history  and  distribution,  600,  604, 
606,  620. 

Tribes  in  mineralogy,  314,  321. 

Triads,  Eaton's,  518,  527. 

Tri,i8,  supposed  altered  of  Alps,  467,  470, 
48 1,683,  684.    See  Glanzschiefer. 

Triple  division  of  utiata,  Eaton'    '.IS,  527. 

Tridymite,  151,  157,  3(C,  687. 

Trinity  College,  Cambridge,  Eng.,  61. 

Troy,  N.  \.,  Cambrian  of,  G39. 

Tschermak  on  intermediate  feldspars, 
295,  304 ;  on  scapolites,  340  et  seq. 

Tungstates,  complex,  386  et  seq. ;  unit- 
weights,  392. 

Turgite,  635. 

Tuscany,  serpentines  of,  462  et  seq.,  486, 
490  et  seq.,  492. 

Tyndall,  physics,  12  ;  life  in  matter,  20 ; 
terrestrial  atmosphere,  44. 

Unit-volcme,  303,  391,  394  ;  of  various 
species,  291,  392.  See  Molecular  vol- 
umes. 

Unit-weight  of  species,  303,  391 ;  how 
calculated,  325. 

Universal  anim.ation,  16,  note,  18. 

Uplifts  or  faults  in  strata,  693,  602,639 
e<seg.,  644,  671. 


Upper  Taconlc.    See  Taconio  slates. 
Upper  Copper-bearing  rocks  of  Logan. 

.See  Kewoenian. 
Ural  Mountains,  geology  of,  505,  680. 
Urschiefer  series  of  Norway,  407. 
Urseren,  Switzerland,  rocks  of,  470. 
Utah,  geology  of,  623,  676. 
Utica  slato,  520,  522,  524,  537. 
Uzielli,  serpentines,.  495. 

V  =  Unit-voljme.    See  Unit-volume. 

Vf     urn  of  space,  62. 

V'altelline,  Italy,  geology  of,  478. 

Vanadates,  347  ;  with  silicate,  347  ;  com- 
plex, 387  et  seq, 

Vanhise,  crystallizing  of  feldspars,  174. 

Vanuxem,  Lardner,  IIudson-Kiver  group, 
its  two  divisions,  624  et  seq.,  002 ;  ser- 
pentines of  Syracuse,  N.  Y.,  443  et  seq. 

Veinstones,  origin  of,  71,  72,  74,  95,  121  et 
aeq.,  128,  243 ;  stratifloation  in,  223  et 
seq.,  225  et  seq.,  231, 234 ;  relations  of  to 
strata,  124, 125,  230, 241, 243  ;  of  :Montal- 
bau  series,  124,  223  ;  Laureutian,  223  et 
seq. ;  calcareous,  228  et  seq.,  231 ;  apa- 
tite-bearing, 232  et  seq. 

Venerite,  a  copper-chloritc,  367  et  seq., 
note,  568. 

Vermont,  Ked  San-^".  ock  of,  593,  608,  630, 
63S;  Cambrian  „  501,  520,  584,  594; 
fossiliferous  liiucstones,  631  et  seq., 
633. 

Vernon  Harcourt,  W.,  on  Newton,  51. 

Ville,  solubility  of  iron  carbon.ate,  266, 
note. 

Vindhyan,  Lower,  rocks  of  India,  564, 
680. 

Virginia,  geology  of,  556,  662  et  seq. 

Virlet  d'Aoust,  serpentines,  502. 

Vitality  of  matter,  10,  18  ;  Rosmini  on, 
16,  note ;  Huxley  on,  18,  note. 

Vital  force,  11,  16  et  seq.,  20,  22,  28.  .See 
Biotic. 

Volcanic,  action,  sent  of ,  40,  117  etseq.; 
causes  of,  lS(i ;  series  of  Logan,  611  et 
seq. ;  hypothesis  of  rock-formation  (see 
Exoplntonic  hypothesis). 

Vnlc!inoes,  Werner  on,  71,  217;  Scrope 
on,  201. 

Volger,  metasomatism,  102, 103. 

Waixott,  C.  D.,  Cambrian,  623  ;  Kewee- 

nian,  625. 
Wales,  crystalline  rocks  of,  416  et  seq., 

420. 


710 


INDEX. 


Waltershausen,  Von,  earth's  interior,  88, 
207;  crystalline  admixtures,  294,  296, 
304. 

Wappinger  Valley,  N.  Y.,  geology  of, 
642. 

Warwick,  Penn.,  iron-ores  of,  551. 

Wasatch  Mountains,  Cambrian  of,  623. 

Washington  Co.,  N.  Y.,  section  of  First 
Graywacke  in,  592. 

Water  In  silicates,  291,  298,  306 ;  in 
igneous  rocks  (see  Hydroplutonlo 
agency). 

Waters,  their  part  In  crenltic  action,  218 
(see  Crenltic  process) ;  mineral,  alkaline, 
218  ;  fossil  sea-waters,  253. 

Water-glass,  Fr^iny  on,  149  ;  Ordway  on, 
149  ei  seq. ;  its  solvent  action  on  met- 
allic oxyds,  150,  181,  240. 

Water-lime  group,  527. 

Way,  C.  J.,  artificial  formation  of  sili- 
cates, 155, 158. 

Webster,  J.  W.,  rock-decay,  248. 

Weisbacb,  mineral  system  of,  381  et  seq,, 
note. 

Werner,  his  classification  of  rocks,  69  et 
seq. ;  great  divisions  of,  113, 190  ;  origin 
of  crystalline  rocks,  69,  71,  76,  105; 
mineral  veins,  71 ;  granites,  72  et  seq. ; 
volcanoes,  71 ;  eruptive  rocks,  217 ; 
sources  of  information  regarding,  71, 
note;  his  classificutiou  In  mineralogy, 
279,  280. 

Westanlte,  365. 

Westchester  Co.,  N.  Y.,  Its  geology,  656 ; 
J.  D.  Dana  on,  663,  665  et  seq. ;  Laureu- 
tlan  of,  666;  Montalban  of,  607. 

West  Indian  Islands,  geology  of,  681  et 
seq.,  683. 

Wheatland,  Penn.,  iron-ores  of,  550. 

White,  C.  A.,  rock-decay,  270. 

White  Mountains,  rocks  of,  406,  463,  480, 
621,  657e<se9.,664. 

Whitney,  J.  D.,  orthoclase  with  zeolites, 
120 ;  rock-decay,  249 ;  Azoic  rocks,  405 ; 
serpentines,  429;  geology  of  Lake  Supe- 
rior, 613. 

Wlcklow  Hills,  Ireland,  423. 


Williams,  C.  Greville,  fusion  of  minerals, 

299  et  seq.,  note. 
Willianis,  W.  Mattieu,  solar  heat,  42,  64; 

interstellar  space,  ibid. 
Winchell,  N.  H.,  rock-decay,  270 ;  Ani- 

nilklo  series,  578;  geology  of  Minnesota, 

679. 
Windsor  basin,  Quebec,  671. 
Wlsoonsin,  kaolin  of,  127,  254 ;  petrosilex 

of,  546  ;  Hall's  Geology  of,  cited,  601. 
Woodstock,  N.  B.,  fossillferouB  limestone 

of,  193. 
Worcester,    Ai'ass.,    veins    near,    123; 

gneisses  of,  274,  note. 
Wrekin,  Shropshire,  rocks  of,  421. 
Wurtz,  Ad.,  polysillcates,  298. 
Wurtz,  Henry,  varying  density  of  solids, 

395  et  seq. ;  his  Geometrical  Chemistry, 

396 ;  geology  of  North  Carolina,  669. 

Xantbobthite,  a  zeolitoid,  336. 

YouNO,  C.  A.,  interstellar  space,  49. 
Younger  gneisses.  See  Gneisses,  younger. 

Zeolites,  name  of,  SM ;  conditions  of 
formation  of,  120;  as  secretions  from 
basic  rocks,  134  et  seq.,  138,  307 ;  bnses 
of,  144 ;  formed  in  deep-sea  ooze,  154 ; 
contemporaneous  formation  of,  !5C  et 
seq.,  153,  185 ;  artificial  formation  of, 
155  et  seq.,  158 ;  paragene<«is  of,  143 ; 
Cross  and  Hildebrand  on,  135 ;  Emer.- 
son  on,  138, 139  ;  table  of,  with  related 
species,  141;  order  of,  281,  313. 

Zeolitoids,  tribe  of,  316,  334;  table  of,  336. 

Zinc-ores,  in  Laureutian,  231;  Xaconlan, 
636,  538. 

Zirconio  oxyd  in  silicates,  306,  335,  344, 
365,  366,  367. 

Zircons,  Linnemann  on,  214;  varying 
density  of,  366. 

Zirkel,  Iherzolite,  608. 

Zoisite,  its  relations  to  meionite  and 
Jadelte,  299,  301,  348. 

ZOUner,  comets,  64;  interstellar  space,  66. 

Zodlogy,  its  objects,  25, 28. 


,    ■;     iiHS 


ion  of  minerals, 

lar  heat,  42,  64; 

Bcay,  270 ;  Anl- 
;y  of  Minnesota, 

71. 

254 ;  potrosilex 
of,  cited,  601. 
erous  limestone 

13    near,    123 ; 

;8  of,  421. 

,298. 

iiisity  of  solids, 

ical  Chemistry, 

Carolina,  669. 

>id,  336. 

r  space,  49. 
sisses,  younger. 

conditions  of 
lecretions  from 
138,  307 ;  bnses 
i-sea  ooze,  154 ; 
ition  of,  150  it 

formation  of, 
eiiesia  of,  143; 
)n,  135 ;  Kmer- 
f,  with  related 
11,  313. 

4;  table  of,  336. 
231;  Taconian, 

I,  306,' 335,  344, 

214 ;    varying 

meionite   and 
;ellar  space,  65. 


